--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.base/share/classes/java/lang/ClassLoader.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,2933 @@
+/*
+ * Copyright (c) 2013, 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang;
+
+import java.io.InputStream;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.io.File;
+import java.lang.reflect.Constructor;
+import java.net.URL;
+import java.security.AccessController;
+import java.security.AccessControlContext;
+import java.security.CodeSource;
+import java.security.PrivilegedAction;
+import java.security.ProtectionDomain;
+import java.security.cert.Certificate;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Hashtable;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.Set;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.Stack;
+import java.util.Vector;
+import java.util.WeakHashMap;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import jdk.internal.perf.PerfCounter;
+import jdk.internal.loader.BootLoader;
+import jdk.internal.loader.ClassLoaders;
+import jdk.internal.misc.SharedSecrets;
+import jdk.internal.misc.Unsafe;
+import jdk.internal.misc.VM;
+import jdk.internal.reflect.CallerSensitive;
+import jdk.internal.reflect.Reflection;
+import sun.reflect.misc.ReflectUtil;
+import sun.security.util.SecurityConstants;
+
+/**
+ * A class loader is an object that is responsible for loading classes. The
+ * class {@code ClassLoader} is an abstract class. Given the <a
+ * href="#name">binary name</a> of a class, a class loader should attempt to
+ * locate or generate data that constitutes a definition for the class. A
+ * typical strategy is to transform the name into a file name and then read a
+ * "class file" of that name from a file system.
+ *
+ * <p> Every {@link java.lang.Class Class} object contains a {@link
+ * Class#getClassLoader() reference} to the {@code ClassLoader} that defined
+ * it.
+ *
+ * <p> {@code Class} objects for array classes are not created by class
+ * loaders, but are created automatically as required by the Java runtime.
+ * The class loader for an array class, as returned by {@link
+ * Class#getClassLoader()} is the same as the class loader for its element
+ * type; if the element type is a primitive type, then the array class has no
+ * class loader.
+ *
+ * <p> Applications implement subclasses of {@code ClassLoader} in order to
+ * extend the manner in which the Java virtual machine dynamically loads
+ * classes.
+ *
+ * <p> Class loaders may typically be used by security managers to indicate
+ * security domains.
+ *
+ * <p> In addition to loading classes, a class loader is also responsible for
+ * locating resources. A resource is some data (a "{@code .class}" file,
+ * configuration data, or an image for example) that is identified with an
+ * abstract '/'-separated path name. Resources are typically packaged with an
+ * application or library so that they can be located by code in the
+ * application or library. In some cases, the resources are included so that
+ * they can be located by other libraries.
+ *
+ * <p> The {@code ClassLoader} class uses a delegation model to search for
+ * classes and resources. Each instance of {@code ClassLoader} has an
+ * associated parent class loader. When requested to find a class or
+ * resource, a {@code ClassLoader} instance will usually delegate the search
+ * for the class or resource to its parent class loader before attempting to
+ * find the class or resource itself.
+ *
+ * <p> Class loaders that support concurrent loading of classes are known as
+ * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class
+ * loaders and are required to register themselves at their class initialization
+ * time by invoking the {@link
+ * #registerAsParallelCapable ClassLoader.registerAsParallelCapable}
+ * method. Note that the {@code ClassLoader} class is registered as parallel
+ * capable by default. However, its subclasses still need to register themselves
+ * if they are parallel capable.
+ * In environments in which the delegation model is not strictly
+ * hierarchical, class loaders need to be parallel capable, otherwise class
+ * loading can lead to deadlocks because the loader lock is held for the
+ * duration of the class loading process (see {@link #loadClass
+ * loadClass} methods).
+ *
+ * <h3> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h3>
+ *
+ * The Java run-time has the following built-in class loaders:
+ *
+ * <ul>
+ * <li><p>Bootstrap class loader.
+ * It is the virtual machine's built-in class loader, typically represented
+ * as {@code null}, and does not have a parent.</li>
+ * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}.
+ * All <em>platform classes</em> are visible to the platform class loader
+ * that can be used as the parent of a {@code ClassLoader} instance.
+ * Platform classes include Java SE platform APIs, their implementation
+ * classes and JDK-specific run-time classes that are defined by the
+ * platform class loader or its ancestors.
+ * <p> To allow for upgrading/overriding of modules defined to the platform
+ * class loader, and where upgraded modules read modules defined to class
+ * loaders other than the platform class loader and its ancestors, then
+ * the platform class loader may have to delegate to other class loaders,
+ * the application class loader for example.
+ * In other words, classes in named modules defined to class loaders
+ * other than the platform class loader and its ancestors may be visible
+ * to the platform class loader. </li>
+ * <li><p>{@linkplain #getSystemClassLoader() System class loader}.
+ * It is also known as <em>application class loader</em> and is distinct
+ * from the platform class loader.
+ * The system class loader is typically used to define classes on the
+ * application class path, module path, and JDK-specific tools.
+ * The platform class loader is a parent or an ancestor of the system class
+ * loader that all platform classes are visible to it.</li>
+ * </ul>
+ *
+ * <p> Normally, the Java virtual machine loads classes from the local file
+ * system in a platform-dependent manner.
+ * However, some classes may not originate from a file; they may originate
+ * from other sources, such as the network, or they could be constructed by an
+ * application. The method {@link #defineClass(String, byte[], int, int)
+ * defineClass} converts an array of bytes into an instance of class
+ * {@code Class}. Instances of this newly defined class can be created using
+ * {@link Class#newInstance Class.newInstance}.
+ *
+ * <p> The methods and constructors of objects created by a class loader may
+ * reference other classes. To determine the class(es) referred to, the Java
+ * virtual machine invokes the {@link #loadClass loadClass} method of
+ * the class loader that originally created the class.
+ *
+ * <p> For example, an application could create a network class loader to
+ * download class files from a server. Sample code might look like:
+ *
+ * <blockquote><pre>
+ * ClassLoader loader = new NetworkClassLoader(host, port);
+ * Object main = loader.loadClass("Main", true).newInstance();
+ * . . .
+ * </pre></blockquote>
+ *
+ * <p> The network class loader subclass must define the methods {@link
+ * #findClass findClass} and {@code loadClassData} to load a class
+ * from the network. Once it has downloaded the bytes that make up the class,
+ * it should use the method {@link #defineClass defineClass} to
+ * create a class instance. A sample implementation is:
+ *
+ * <blockquote><pre>
+ * class NetworkClassLoader extends ClassLoader {
+ * String host;
+ * int port;
+ *
+ * public Class findClass(String name) {
+ * byte[] b = loadClassData(name);
+ * return defineClass(name, b, 0, b.length);
+ * }
+ *
+ * private byte[] loadClassData(String name) {
+ * // load the class data from the connection
+ * . . .
+ * }
+ * }
+ * </pre></blockquote>
+ *
+ * <h3> <a id="name">Binary names</a> </h3>
+ *
+ * <p> Any class name provided as a {@code String} parameter to methods in
+ * {@code ClassLoader} must be a binary name as defined by
+ * <cite>The Java™ Language Specification</cite>.
+ *
+ * <p> Examples of valid class names include:
+ * <blockquote><pre>
+ * "java.lang.String"
+ * "javax.swing.JSpinner$DefaultEditor"
+ * "java.security.KeyStore$Builder$FileBuilder$1"
+ * "java.net.URLClassLoader$3$1"
+ * </pre></blockquote>
+ *
+ * <p> Any package name provided as a {@code String} parameter to methods in
+ * {@code ClassLoader} must be either the empty string (denoting an unnamed package)
+ * or a fully qualified name as defined by
+ * <cite>The Java™ Language Specification</cite>.
+ *
+ * @jls 6.7 Fully Qualified Names
+ * @jls 13.1 The Form of a Binary
+ * @see #resolveClass(Class)
+ * @since 1.0
+ * @revised 9
+ * @spec JPMS
+ */
+public abstract class ClassLoader {
+
+ private static native void registerNatives();
+ static {
+ registerNatives();
+ }
+
+ // The parent class loader for delegation
+ // Note: VM hardcoded the offset of this field, thus all new fields
+ // must be added *after* it.
+ private final ClassLoader parent;
+
+ // class loader name
+ private final String name;
+
+ // the unnamed module for this ClassLoader
+ private final Module unnamedModule;
+
+ /**
+ * Encapsulates the set of parallel capable loader types.
+ */
+ private static class ParallelLoaders {
+ private ParallelLoaders() {}
+
+ // the set of parallel capable loader types
+ private static final Set<Class<? extends ClassLoader>> loaderTypes =
+ Collections.newSetFromMap(new WeakHashMap<>());
+ static {
+ synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); }
+ }
+
+ /**
+ * Registers the given class loader type as parallel capable.
+ * Returns {@code true} is successfully registered; {@code false} if
+ * loader's super class is not registered.
+ */
+ static boolean register(Class<? extends ClassLoader> c) {
+ synchronized (loaderTypes) {
+ if (loaderTypes.contains(c.getSuperclass())) {
+ // register the class loader as parallel capable
+ // if and only if all of its super classes are.
+ // Note: given current classloading sequence, if
+ // the immediate super class is parallel capable,
+ // all the super classes higher up must be too.
+ loaderTypes.add(c);
+ return true;
+ } else {
+ return false;
+ }
+ }
+ }
+
+ /**
+ * Returns {@code true} if the given class loader type is
+ * registered as parallel capable.
+ */
+ static boolean isRegistered(Class<? extends ClassLoader> c) {
+ synchronized (loaderTypes) {
+ return loaderTypes.contains(c);
+ }
+ }
+ }
+
+ // Maps class name to the corresponding lock object when the current
+ // class loader is parallel capable.
+ // Note: VM also uses this field to decide if the current class loader
+ // is parallel capable and the appropriate lock object for class loading.
+ private final ConcurrentHashMap<String, Object> parallelLockMap;
+
+ // Maps packages to certs
+ private final Map <String, Certificate[]> package2certs;
+
+ // Shared among all packages with unsigned classes
+ private static final Certificate[] nocerts = new Certificate[0];
+
+ // The classes loaded by this class loader. The only purpose of this table
+ // is to keep the classes from being GC'ed until the loader is GC'ed.
+ private final Vector<Class<?>> classes = new Vector<>();
+
+ // The "default" domain. Set as the default ProtectionDomain on newly
+ // created classes.
+ private final ProtectionDomain defaultDomain =
+ new ProtectionDomain(new CodeSource(null, (Certificate[]) null),
+ null, this, null);
+
+ // Invoked by the VM to record every loaded class with this loader.
+ void addClass(Class<?> c) {
+ classes.addElement(c);
+ }
+
+ // The packages defined in this class loader. Each package name is
+ // mapped to its corresponding NamedPackage object.
+ //
+ // The value is a Package object if ClassLoader::definePackage,
+ // Class::getPackage, ClassLoader::getDefinePackage(s) or
+ // Package::getPackage(s) method is called to define it.
+ // Otherwise, the value is a NamedPackage object.
+ private final ConcurrentHashMap<String, NamedPackage> packages
+ = new ConcurrentHashMap<>();
+
+ /*
+ * Returns a named package for the given module.
+ */
+ private NamedPackage getNamedPackage(String pn, Module m) {
+ NamedPackage p = packages.get(pn);
+ if (p == null) {
+ p = new NamedPackage(pn, m);
+
+ NamedPackage value = packages.putIfAbsent(pn, p);
+ if (value != null) {
+ // Package object already be defined for the named package
+ p = value;
+ // if definePackage is called by this class loader to define
+ // a package in a named module, this will return Package
+ // object of the same name. Package object may contain
+ // unexpected information but it does not impact the runtime.
+ // this assertion may be helpful for troubleshooting
+ assert value.module() == m;
+ }
+ }
+ return p;
+ }
+
+ private static Void checkCreateClassLoader() {
+ return checkCreateClassLoader(null);
+ }
+
+ private static Void checkCreateClassLoader(String name) {
+ if (name != null && name.isEmpty()) {
+ throw new IllegalArgumentException("name must be non-empty or null");
+ }
+
+ SecurityManager security = System.getSecurityManager();
+ if (security != null) {
+ security.checkCreateClassLoader();
+ }
+ return null;
+ }
+
+ private ClassLoader(Void unused, String name, ClassLoader parent) {
+ this.name = name;
+ this.parent = parent;
+ this.unnamedModule = new Module(this);
+ if (ParallelLoaders.isRegistered(this.getClass())) {
+ parallelLockMap = new ConcurrentHashMap<>();
+ package2certs = new ConcurrentHashMap<>();
+ assertionLock = new Object();
+ } else {
+ // no finer-grained lock; lock on the classloader instance
+ parallelLockMap = null;
+ package2certs = new Hashtable<>();
+ assertionLock = this;
+ }
+ }
+
+ /**
+ * Creates a new class loader of the specified name and using the
+ * specified parent class loader for delegation.
+ *
+ * @apiNote If the parent is specified as {@code null} (for the
+ * bootstrap class loader) then there is no guarantee that all platform
+ * classes are visible.
+ *
+ * @param name class loader name; or {@code null} if not named
+ * @param parent the parent class loader
+ *
+ * @throws IllegalArgumentException if the given name is empty.
+ *
+ * @throws SecurityException
+ * If a security manager exists and its
+ * {@link SecurityManager#checkCreateClassLoader()}
+ * method doesn't allow creation of a new class loader.
+ *
+ * @since 9
+ * @spec JPMS
+ */
+ protected ClassLoader(String name, ClassLoader parent) {
+ this(checkCreateClassLoader(name), name, parent);
+ }
+
+ /**
+ * Creates a new class loader using the specified parent class loader for
+ * delegation.
+ *
+ * <p> If there is a security manager, its {@link
+ * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method
+ * is invoked. This may result in a security exception. </p>
+ *
+ * @apiNote If the parent is specified as {@code null} (for the
+ * bootstrap class loader) then there is no guarantee that all platform
+ * classes are visible.
+ *
+ * @param parent
+ * The parent class loader
+ *
+ * @throws SecurityException
+ * If a security manager exists and its
+ * {@code checkCreateClassLoader} method doesn't allow creation
+ * of a new class loader.
+ *
+ * @since 1.2
+ */
+ protected ClassLoader(ClassLoader parent) {
+ this(checkCreateClassLoader(), null, parent);
+ }
+
+ /**
+ * Creates a new class loader using the {@code ClassLoader} returned by
+ * the method {@link #getSystemClassLoader()
+ * getSystemClassLoader()} as the parent class loader.
+ *
+ * <p> If there is a security manager, its {@link
+ * SecurityManager#checkCreateClassLoader()
+ * checkCreateClassLoader} method is invoked. This may result in
+ * a security exception. </p>
+ *
+ * @throws SecurityException
+ * If a security manager exists and its
+ * {@code checkCreateClassLoader} method doesn't allow creation
+ * of a new class loader.
+ */
+ protected ClassLoader() {
+ this(checkCreateClassLoader(), null, getSystemClassLoader());
+ }
+
+ /**
+ * Returns the name of this class loader or {@code null} if
+ * this class loader is not named.
+ *
+ * @apiNote This method is non-final for compatibility. If this
+ * method is overridden, this method must return the same name
+ * as specified when this class loader was instantiated.
+ *
+ * @return name of this class loader; or {@code null} if
+ * this class loader is not named.
+ *
+ * @since 9
+ * @spec JPMS
+ */
+ public String getName() {
+ return name;
+ }
+
+ // package-private used by StackTraceElement to avoid
+ // calling the overrideable getName method
+ final String name() {
+ return name;
+ }
+
+ // -- Class --
+
+ /**
+ * Loads the class with the specified <a href="#name">binary name</a>.
+ * This method searches for classes in the same manner as the {@link
+ * #loadClass(String, boolean)} method. It is invoked by the Java virtual
+ * machine to resolve class references. Invoking this method is equivalent
+ * to invoking {@link #loadClass(String, boolean) loadClass(name,
+ * false)}.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The resulting {@code Class} object
+ *
+ * @throws ClassNotFoundException
+ * If the class was not found
+ */
+ public Class<?> loadClass(String name) throws ClassNotFoundException {
+ return loadClass(name, false);
+ }
+
+ /**
+ * Loads the class with the specified <a href="#name">binary name</a>. The
+ * default implementation of this method searches for classes in the
+ * following order:
+ *
+ * <ol>
+ *
+ * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class
+ * has already been loaded. </p></li>
+ *
+ * <li><p> Invoke the {@link #loadClass(String) loadClass} method
+ * on the parent class loader. If the parent is {@code null} the class
+ * loader built into the virtual machine is used, instead. </p></li>
+ *
+ * <li><p> Invoke the {@link #findClass(String)} method to find the
+ * class. </p></li>
+ *
+ * </ol>
+ *
+ * <p> If the class was found using the above steps, and the
+ * {@code resolve} flag is true, this method will then invoke the {@link
+ * #resolveClass(Class)} method on the resulting {@code Class} object.
+ *
+ * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link
+ * #findClass(String)}, rather than this method. </p>
+ *
+ * <p> Unless overridden, this method synchronizes on the result of
+ * {@link #getClassLoadingLock getClassLoadingLock} method
+ * during the entire class loading process.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @param resolve
+ * If {@code true} then resolve the class
+ *
+ * @return The resulting {@code Class} object
+ *
+ * @throws ClassNotFoundException
+ * If the class could not be found
+ */
+ protected Class<?> loadClass(String name, boolean resolve)
+ throws ClassNotFoundException
+ {
+ synchronized (getClassLoadingLock(name)) {
+ // First, check if the class has already been loaded
+ Class<?> c = findLoadedClass(name);
+ if (c == null) {
+ long t0 = System.nanoTime();
+ try {
+ if (parent != null) {
+ c = parent.loadClass(name, false);
+ } else {
+ c = findBootstrapClassOrNull(name);
+ }
+ } catch (ClassNotFoundException e) {
+ // ClassNotFoundException thrown if class not found
+ // from the non-null parent class loader
+ }
+
+ if (c == null) {
+ // If still not found, then invoke findClass in order
+ // to find the class.
+ long t1 = System.nanoTime();
+ c = findClass(name);
+
+ // this is the defining class loader; record the stats
+ PerfCounter.getParentDelegationTime().addTime(t1 - t0);
+ PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
+ PerfCounter.getFindClasses().increment();
+ }
+ }
+ if (resolve) {
+ resolveClass(c);
+ }
+ return c;
+ }
+ }
+
+ /**
+ * Loads the class with the specified <a href="#name">binary name</a>
+ * in a module defined to this class loader. This method returns {@code null}
+ * if the class could not be found.
+ *
+ * @apiNote This method does not delegate to the parent class loader.
+ *
+ * @implSpec The default implementation of this method searches for classes
+ * in the following order:
+ *
+ * <ol>
+ * <li>Invoke {@link #findLoadedClass(String)} to check if the class
+ * has already been loaded.</li>
+ * <li>Invoke the {@link #findClass(String, String)} method to find the
+ * class in the given module.</li>
+ * </ol>
+ *
+ * @param module
+ * The module
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The resulting {@code Class} object in a module defined by
+ * this class loader, or {@code null} if the class could not be found.
+ */
+ final Class<?> loadClass(Module module, String name) {
+ synchronized (getClassLoadingLock(name)) {
+ // First, check if the class has already been loaded
+ Class<?> c = findLoadedClass(name);
+ if (c == null) {
+ c = findClass(module.getName(), name);
+ }
+ if (c != null && c.getModule() == module) {
+ return c;
+ } else {
+ return null;
+ }
+ }
+ }
+
+ /**
+ * Returns the lock object for class loading operations.
+ * For backward compatibility, the default implementation of this method
+ * behaves as follows. If this ClassLoader object is registered as
+ * parallel capable, the method returns a dedicated object associated
+ * with the specified class name. Otherwise, the method returns this
+ * ClassLoader object.
+ *
+ * @param className
+ * The name of the to-be-loaded class
+ *
+ * @return the lock for class loading operations
+ *
+ * @throws NullPointerException
+ * If registered as parallel capable and {@code className} is null
+ *
+ * @see #loadClass(String, boolean)
+ *
+ * @since 1.7
+ */
+ protected Object getClassLoadingLock(String className) {
+ Object lock = this;
+ if (parallelLockMap != null) {
+ Object newLock = new Object();
+ lock = parallelLockMap.putIfAbsent(className, newLock);
+ if (lock == null) {
+ lock = newLock;
+ }
+ }
+ return lock;
+ }
+
+ // This method is invoked by the virtual machine to load a class.
+ private Class<?> loadClassInternal(String name)
+ throws ClassNotFoundException
+ {
+ // For backward compatibility, explicitly lock on 'this' when
+ // the current class loader is not parallel capable.
+ if (parallelLockMap == null) {
+ synchronized (this) {
+ return loadClass(name);
+ }
+ } else {
+ return loadClass(name);
+ }
+ }
+
+ // Invoked by the VM after loading class with this loader.
+ private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) {
+ final SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ if (ReflectUtil.isNonPublicProxyClass(cls)) {
+ for (Class<?> intf: cls.getInterfaces()) {
+ checkPackageAccess(intf, pd);
+ }
+ return;
+ }
+
+ final String name = cls.getName();
+ final int i = name.lastIndexOf('.');
+ if (i != -1) {
+ AccessController.doPrivileged(new PrivilegedAction<>() {
+ public Void run() {
+ sm.checkPackageAccess(name.substring(0, i));
+ return null;
+ }
+ }, new AccessControlContext(new ProtectionDomain[] {pd}));
+ }
+ }
+ }
+
+ /**
+ * Finds the class with the specified <a href="#name">binary name</a>.
+ * This method should be overridden by class loader implementations that
+ * follow the delegation model for loading classes, and will be invoked by
+ * the {@link #loadClass loadClass} method after checking the
+ * parent class loader for the requested class.
+ *
+ * @implSpec The default implementation throws {@code ClassNotFoundException}.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The resulting {@code Class} object
+ *
+ * @throws ClassNotFoundException
+ * If the class could not be found
+ *
+ * @since 1.2
+ */
+ protected Class<?> findClass(String name) throws ClassNotFoundException {
+ throw new ClassNotFoundException(name);
+ }
+
+ /**
+ * Finds the class with the given <a href="#name">binary name</a>
+ * in a module defined to this class loader.
+ * Class loader implementations that support the loading from modules
+ * should override this method.
+ *
+ * @apiNote This method returns {@code null} rather than throwing
+ * {@code ClassNotFoundException} if the class could not be found.
+ *
+ * @implSpec The default implementation attempts to find the class by
+ * invoking {@link #findClass(String)} when the {@code moduleName} is
+ * {@code null}. It otherwise returns {@code null}.
+ *
+ * @param moduleName
+ * The module name; or {@code null} to find the class in the
+ * {@linkplain #getUnnamedModule() unnamed module} for this
+ * class loader
+
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The resulting {@code Class} object, or {@code null}
+ * if the class could not be found.
+ *
+ * @since 9
+ * @spec JPMS
+ */
+ protected Class<?> findClass(String moduleName, String name) {
+ if (moduleName == null) {
+ try {
+ return findClass(name);
+ } catch (ClassNotFoundException ignore) { }
+ }
+ return null;
+ }
+
+
+ /**
+ * Converts an array of bytes into an instance of class {@code Class}.
+ * Before the {@code Class} can be used it must be resolved. This method
+ * is deprecated in favor of the version that takes a <a
+ * href="#name">binary name</a> as its first argument, and is more secure.
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes in positions
+ * {@code off} through {@code off+len-1} should have the format
+ * of a valid class file as defined by
+ * <cite>The Java™ Virtual Machine Specification</cite>.
+ *
+ * @param off
+ * The start offset in {@code b} of the class data
+ *
+ * @param len
+ * The length of the class data
+ *
+ * @return The {@code Class} object that was created from the specified
+ * class data
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class
+ *
+ * @throws IndexOutOfBoundsException
+ * If either {@code off} or {@code len} is negative, or if
+ * {@code off+len} is greater than {@code b.length}.
+ *
+ * @throws SecurityException
+ * If an attempt is made to add this class to a package that
+ * contains classes that were signed by a different set of
+ * certificates than this class, or if an attempt is made
+ * to define a class in a package with a fully-qualified name
+ * that starts with "{@code java.}".
+ *
+ * @see #loadClass(String, boolean)
+ * @see #resolveClass(Class)
+ *
+ * @deprecated Replaced by {@link #defineClass(String, byte[], int, int)
+ * defineClass(String, byte[], int, int)}
+ */
+ @Deprecated(since="1.1")
+ protected final Class<?> defineClass(byte[] b, int off, int len)
+ throws ClassFormatError
+ {
+ return defineClass(null, b, off, len, null);
+ }
+
+ /**
+ * Converts an array of bytes into an instance of class {@code Class}.
+ * Before the {@code Class} can be used it must be resolved.
+ *
+ * <p> This method assigns a default {@link java.security.ProtectionDomain
+ * ProtectionDomain} to the newly defined class. The
+ * {@code ProtectionDomain} is effectively granted the same set of
+ * permissions returned when {@link
+ * java.security.Policy#getPermissions(java.security.CodeSource)
+ * Policy.getPolicy().getPermissions(new CodeSource(null, null))}
+ * is invoked. The default protection domain is created on the first invocation
+ * of {@link #defineClass(String, byte[], int, int) defineClass},
+ * and re-used on subsequent invocations.
+ *
+ * <p> To assign a specific {@code ProtectionDomain} to the class, use
+ * the {@link #defineClass(String, byte[], int, int,
+ * java.security.ProtectionDomain) defineClass} method that takes a
+ * {@code ProtectionDomain} as one of its arguments. </p>
+ *
+ * <p>
+ * This method defines a package in this class loader corresponding to the
+ * package of the {@code Class} (if such a package has not already been defined
+ * in this class loader). The name of the defined package is derived from
+ * the <a href="#name">binary name</a> of the class specified by
+ * the byte array {@code b}.
+ * Other properties of the defined package are as specified by {@link Package}.
+ *
+ * @param name
+ * The expected <a href="#name">binary name</a> of the class, or
+ * {@code null} if not known
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes in positions
+ * {@code off} through {@code off+len-1} should have the format
+ * of a valid class file as defined by
+ * <cite>The Java™ Virtual Machine Specification</cite>.
+ *
+ * @param off
+ * The start offset in {@code b} of the class data
+ *
+ * @param len
+ * The length of the class data
+ *
+ * @return The {@code Class} object that was created from the specified
+ * class data.
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class
+ *
+ * @throws IndexOutOfBoundsException
+ * If either {@code off} or {@code len} is negative, or if
+ * {@code off+len} is greater than {@code b.length}.
+ *
+ * @throws SecurityException
+ * If an attempt is made to add this class to a package that
+ * contains classes that were signed by a different set of
+ * certificates than this class (which is unsigned), or if
+ * {@code name} begins with "{@code java.}".
+ *
+ * @see #loadClass(String, boolean)
+ * @see #resolveClass(Class)
+ * @see java.security.CodeSource
+ * @see java.security.SecureClassLoader
+ *
+ * @since 1.1
+ * @revised 9
+ * @spec JPMS
+ */
+ protected final Class<?> defineClass(String name, byte[] b, int off, int len)
+ throws ClassFormatError
+ {
+ return defineClass(name, b, off, len, null);
+ }
+
+ /* Determine protection domain, and check that:
+ - not define java.* class,
+ - signer of this class matches signers for the rest of the classes in
+ package.
+ */
+ private ProtectionDomain preDefineClass(String name,
+ ProtectionDomain pd)
+ {
+ if (!checkName(name))
+ throw new NoClassDefFoundError("IllegalName: " + name);
+
+ // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias
+ // relies on the fact that spoofing is impossible if a class has a name
+ // of the form "java.*"
+ if ((name != null) && name.startsWith("java.")
+ && this != getBuiltinPlatformClassLoader()) {
+ throw new SecurityException
+ ("Prohibited package name: " +
+ name.substring(0, name.lastIndexOf('.')));
+ }
+ if (pd == null) {
+ pd = defaultDomain;
+ }
+
+ if (name != null) {
+ checkCerts(name, pd.getCodeSource());
+ }
+
+ return pd;
+ }
+
+ private String defineClassSourceLocation(ProtectionDomain pd) {
+ CodeSource cs = pd.getCodeSource();
+ String source = null;
+ if (cs != null && cs.getLocation() != null) {
+ source = cs.getLocation().toString();
+ }
+ return source;
+ }
+
+ private void postDefineClass(Class<?> c, ProtectionDomain pd) {
+ // define a named package, if not present
+ getNamedPackage(c.getPackageName(), c.getModule());
+
+ if (pd.getCodeSource() != null) {
+ Certificate certs[] = pd.getCodeSource().getCertificates();
+ if (certs != null)
+ setSigners(c, certs);
+ }
+ }
+
+ /**
+ * Converts an array of bytes into an instance of class {@code Class},
+ * with a given {@code ProtectionDomain}.
+ *
+ * <p> If the given {@code ProtectionDomain} is {@code null},
+ * then a default protection domain will be assigned to the class as specified
+ * in the documentation for {@link #defineClass(String, byte[], int, int)}.
+ * Before the class can be used it must be resolved.
+ *
+ * <p> The first class defined in a package determines the exact set of
+ * certificates that all subsequent classes defined in that package must
+ * contain. The set of certificates for a class is obtained from the
+ * {@link java.security.CodeSource CodeSource} within the
+ * {@code ProtectionDomain} of the class. Any classes added to that
+ * package must contain the same set of certificates or a
+ * {@code SecurityException} will be thrown. Note that if
+ * {@code name} is {@code null}, this check is not performed.
+ * You should always pass in the <a href="#name">binary name</a> of the
+ * class you are defining as well as the bytes. This ensures that the
+ * class you are defining is indeed the class you think it is.
+ *
+ * <p> If the specified {@code name} begins with "{@code java.}", it can
+ * only be defined by the {@linkplain #getPlatformClassLoader()
+ * platform class loader} or its ancestors; otherwise {@code SecurityException}
+ * will be thrown. If {@code name} is not {@code null}, it must be equal to
+ * the <a href="#name">binary name</a> of the class
+ * specified by the byte array {@code b}, otherwise a {@link
+ * NoClassDefFoundError NoClassDefFoundError} will be thrown.
+ *
+ * <p> This method defines a package in this class loader corresponding to the
+ * package of the {@code Class} (if such a package has not already been defined
+ * in this class loader). The name of the defined package is derived from
+ * the <a href="#name">binary name</a> of the class specified by
+ * the byte array {@code b}.
+ * Other properties of the defined package are as specified by {@link Package}.
+ *
+ * @param name
+ * The expected <a href="#name">binary name</a> of the class, or
+ * {@code null} if not known
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes in positions
+ * {@code off} through {@code off+len-1} should have the format
+ * of a valid class file as defined by
+ * <cite>The Java™ Virtual Machine Specification</cite>.
+ *
+ * @param off
+ * The start offset in {@code b} of the class data
+ *
+ * @param len
+ * The length of the class data
+ *
+ * @param protectionDomain
+ * The {@code ProtectionDomain} of the class
+ *
+ * @return The {@code Class} object created from the data,
+ * and {@code ProtectionDomain}.
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class
+ *
+ * @throws NoClassDefFoundError
+ * If {@code name} is not {@code null} and not equal to the
+ * <a href="#name">binary name</a> of the class specified by {@code b}
+ *
+ * @throws IndexOutOfBoundsException
+ * If either {@code off} or {@code len} is negative, or if
+ * {@code off+len} is greater than {@code b.length}.
+ *
+ * @throws SecurityException
+ * If an attempt is made to add this class to a package that
+ * contains classes that were signed by a different set of
+ * certificates than this class, or if {@code name} begins with
+ * "{@code java.}" and this class loader is not the platform
+ * class loader or its ancestor.
+ *
+ * @revised 9
+ * @spec JPMS
+ */
+ protected final Class<?> defineClass(String name, byte[] b, int off, int len,
+ ProtectionDomain protectionDomain)
+ throws ClassFormatError
+ {
+ protectionDomain = preDefineClass(name, protectionDomain);
+ String source = defineClassSourceLocation(protectionDomain);
+ Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source);
+ postDefineClass(c, protectionDomain);
+ return c;
+ }
+
+ /**
+ * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance
+ * of class {@code Class}, with the given {@code ProtectionDomain}.
+ * If the given {@code ProtectionDomain} is {@code null}, then a default
+ * protection domain will be assigned to the class as
+ * specified in the documentation for {@link #defineClass(String, byte[],
+ * int, int)}. Before the class can be used it must be resolved.
+ *
+ * <p>The rules about the first class defined in a package determining the
+ * set of certificates for the package, the restrictions on class names,
+ * and the defined package of the class
+ * are identical to those specified in the documentation for {@link
+ * #defineClass(String, byte[], int, int, ProtectionDomain)}.
+ *
+ * <p> An invocation of this method of the form
+ * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,}
+ * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same
+ * result as the statements
+ *
+ *<p> <code>
+ * ...<br>
+ * byte[] temp = new byte[bBuffer.{@link
+ * java.nio.ByteBuffer#remaining remaining}()];<br>
+ * bBuffer.{@link java.nio.ByteBuffer#get(byte[])
+ * get}(temp);<br>
+ * return {@link #defineClass(String, byte[], int, int, ProtectionDomain)
+ * cl.defineClass}(name, temp, 0,
+ * temp.length, pd);<br>
+ * </code></p>
+ *
+ * @param name
+ * The expected <a href="#name">binary name</a>. of the class, or
+ * {@code null} if not known
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes from positions
+ * {@code b.position()} through {@code b.position() + b.limit() -1
+ * } should have the format of a valid class file as defined by
+ * <cite>The Java™ Virtual Machine Specification</cite>.
+ *
+ * @param protectionDomain
+ * The {@code ProtectionDomain} of the class, or {@code null}.
+ *
+ * @return The {@code Class} object created from the data,
+ * and {@code ProtectionDomain}.
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class.
+ *
+ * @throws NoClassDefFoundError
+ * If {@code name} is not {@code null} and not equal to the
+ * <a href="#name">binary name</a> of the class specified by {@code b}
+ *
+ * @throws SecurityException
+ * If an attempt is made to add this class to a package that
+ * contains classes that were signed by a different set of
+ * certificates than this class, or if {@code name} begins with
+ * "{@code java.}".
+ *
+ * @see #defineClass(String, byte[], int, int, ProtectionDomain)
+ *
+ * @since 1.5
+ * @revised 9
+ * @spec JPMS
+ */
+ protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
+ ProtectionDomain protectionDomain)
+ throws ClassFormatError
+ {
+ int len = b.remaining();
+
+ // Use byte[] if not a direct ByteBuffer:
+ if (!b.isDirect()) {
+ if (b.hasArray()) {
+ return defineClass(name, b.array(),
+ b.position() + b.arrayOffset(), len,
+ protectionDomain);
+ } else {
+ // no array, or read-only array
+ byte[] tb = new byte[len];
+ b.get(tb); // get bytes out of byte buffer.
+ return defineClass(name, tb, 0, len, protectionDomain);
+ }
+ }
+
+ protectionDomain = preDefineClass(name, protectionDomain);
+ String source = defineClassSourceLocation(protectionDomain);
+ Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source);
+ postDefineClass(c, protectionDomain);
+ return c;
+ }
+
+ static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len,
+ ProtectionDomain pd, String source);
+
+ static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b,
+ int off, int len, ProtectionDomain pd,
+ String source);
+
+ // true if the name is null or has the potential to be a valid binary name
+ private boolean checkName(String name) {
+ if ((name == null) || (name.length() == 0))
+ return true;
+ if ((name.indexOf('/') != -1) || (name.charAt(0) == '['))
+ return false;
+ return true;
+ }
+
+ private void checkCerts(String name, CodeSource cs) {
+ int i = name.lastIndexOf('.');
+ String pname = (i == -1) ? "" : name.substring(0, i);
+
+ Certificate[] certs = null;
+ if (cs != null) {
+ certs = cs.getCertificates();
+ }
+ Certificate[] pcerts = null;
+ if (parallelLockMap == null) {
+ synchronized (this) {
+ pcerts = package2certs.get(pname);
+ if (pcerts == null) {
+ package2certs.put(pname, (certs == null? nocerts:certs));
+ }
+ }
+ } else {
+ pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs).
+ putIfAbsent(pname, (certs == null? nocerts:certs));
+ }
+ if (pcerts != null && !compareCerts(pcerts, certs)) {
+ throw new SecurityException("class \"" + name
+ + "\"'s signer information does not match signer information"
+ + " of other classes in the same package");
+ }
+ }
+
+ /**
+ * check to make sure the certs for the new class (certs) are the same as
+ * the certs for the first class inserted in the package (pcerts)
+ */
+ private boolean compareCerts(Certificate[] pcerts,
+ Certificate[] certs)
+ {
+ // certs can be null, indicating no certs.
+ if ((certs == null) || (certs.length == 0)) {
+ return pcerts.length == 0;
+ }
+
+ // the length must be the same at this point
+ if (certs.length != pcerts.length)
+ return false;
+
+ // go through and make sure all the certs in one array
+ // are in the other and vice-versa.
+ boolean match;
+ for (Certificate cert : certs) {
+ match = false;
+ for (Certificate pcert : pcerts) {
+ if (cert.equals(pcert)) {
+ match = true;
+ break;
+ }
+ }
+ if (!match) return false;
+ }
+
+ // now do the same for pcerts
+ for (Certificate pcert : pcerts) {
+ match = false;
+ for (Certificate cert : certs) {
+ if (pcert.equals(cert)) {
+ match = true;
+ break;
+ }
+ }
+ if (!match) return false;
+ }
+
+ return true;
+ }
+
+ /**
+ * Links the specified class. This (misleadingly named) method may be
+ * used by a class loader to link a class. If the class {@code c} has
+ * already been linked, then this method simply returns. Otherwise, the
+ * class is linked as described in the "Execution" chapter of
+ * <cite>The Java™ Language Specification</cite>.
+ *
+ * @param c
+ * The class to link
+ *
+ * @throws NullPointerException
+ * If {@code c} is {@code null}.
+ *
+ * @see #defineClass(String, byte[], int, int)
+ */
+ protected final void resolveClass(Class<?> c) {
+ if (c == null) {
+ throw new NullPointerException();
+ }
+ }
+
+ /**
+ * Finds a class with the specified <a href="#name">binary name</a>,
+ * loading it if necessary.
+ *
+ * <p> This method loads the class through the system class loader (see
+ * {@link #getSystemClassLoader()}). The {@code Class} object returned
+ * might have more than one {@code ClassLoader} associated with it.
+ * Subclasses of {@code ClassLoader} need not usually invoke this method,
+ * because most class loaders need to override just {@link
+ * #findClass(String)}. </p>
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The {@code Class} object for the specified {@code name}
+ *
+ * @throws ClassNotFoundException
+ * If the class could not be found
+ *
+ * @see #ClassLoader(ClassLoader)
+ * @see #getParent()
+ */
+ protected final Class<?> findSystemClass(String name)
+ throws ClassNotFoundException
+ {
+ return getSystemClassLoader().loadClass(name);
+ }
+
+ /**
+ * Returns a class loaded by the bootstrap class loader;
+ * or return null if not found.
+ */
+ Class<?> findBootstrapClassOrNull(String name) {
+ if (!checkName(name)) return null;
+
+ return findBootstrapClass(name);
+ }
+
+ // return null if not found
+ private native Class<?> findBootstrapClass(String name);
+
+ /**
+ * Returns the class with the given <a href="#name">binary name</a> if this
+ * loader has been recorded by the Java virtual machine as an initiating
+ * loader of a class with that <a href="#name">binary name</a>. Otherwise
+ * {@code null} is returned.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The {@code Class} object, or {@code null} if the class has
+ * not been loaded
+ *
+ * @since 1.1
+ */
+ protected final Class<?> findLoadedClass(String name) {
+ if (!checkName(name))
+ return null;
+ return findLoadedClass0(name);
+ }
+
+ private final native Class<?> findLoadedClass0(String name);
+
+ /**
+ * Sets the signers of a class. This should be invoked after defining a
+ * class.
+ *
+ * @param c
+ * The {@code Class} object
+ *
+ * @param signers
+ * The signers for the class
+ *
+ * @since 1.1
+ */
+ protected final void setSigners(Class<?> c, Object[] signers) {
+ c.setSigners(signers);
+ }
+
+
+ // -- Resources --
+
+ /**
+ * Returns a URL to a resource in a module defined to this class loader.
+ * Class loader implementations that support the loading from modules
+ * should override this method.
+ *
+ * @apiNote This method is the basis for the {@link
+ * Class#getResource Class.getResource}, {@link Class#getResourceAsStream
+ * Class.getResourceAsStream}, and {@link Module#getResourceAsStream
+ * Module.getResourceAsStream} methods. It is not subject to the rules for
+ * encapsulation specified by {@code Module.getResourceAsStream}.
+ *
+ * @implSpec The default implementation attempts to find the resource by
+ * invoking {@link #findResource(String)} when the {@code moduleName} is
+ * {@code null}. It otherwise returns {@code null}.
+ *
+ * @param moduleName
+ * The module name; or {@code null} to find a resource in the
+ * {@linkplain #getUnnamedModule() unnamed module} for this
+ * class loader
+ * @param name
+ * The resource name
+ *
+ * @return A URL to the resource; {@code null} if the resource could not be
+ * found, a URL could not be constructed to locate the resource,
+ * access to the resource is denied by the security manager, or
+ * there isn't a module of the given name defined to the class
+ * loader.
+ *
+ * @throws IOException
+ * If I/O errors occur
+ *
+ * @see java.lang.module.ModuleReader#find(String)
+ * @since 9
+ * @spec JPMS
+ */
+ protected URL findResource(String moduleName, String name) throws IOException {
+ if (moduleName == null) {
+ return findResource(name);
+ } else {
+ return null;
+ }
+ }
+
+ /**
+ * Finds the resource with the given name. A resource is some data
+ * (images, audio, text, etc) that can be accessed by class code in a way
+ * that is independent of the location of the code.
+ *
+ * <p> The name of a resource is a '{@code /}'-separated path name that
+ * identifies the resource. </p>
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally (even if the caller of this method is in the
+ * same module as the resource). </p>
+ *
+ * @implSpec The default implementation will first search the parent class
+ * loader for the resource; if the parent is {@code null} the path of the
+ * class loader built into the virtual machine is searched. If not found,
+ * this method will invoke {@link #findResource(String)} to find the resource.
+ *
+ * @apiNote Where several modules are defined to the same class loader,
+ * and where more than one module contains a resource with the given name,
+ * then the ordering that modules are searched is not specified and may be
+ * very unpredictable.
+ * When overriding this method it is recommended that an implementation
+ * ensures that any delegation is consistent with the {@link
+ * #getResources(java.lang.String) getResources(String)} method.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return {@code URL} object for reading the resource; {@code null} if
+ * the resource could not be found, a {@code URL} could not be
+ * constructed to locate the resource, the resource is in a package
+ * that is not opened unconditionally, or access to the resource is
+ * denied by the security manager.
+ *
+ * @throws NullPointerException If {@code name} is {@code null}
+ *
+ * @since 1.1
+ * @revised 9
+ * @spec JPMS
+ */
+ public URL getResource(String name) {
+ Objects.requireNonNull(name);
+ URL url;
+ if (parent != null) {
+ url = parent.getResource(name);
+ } else {
+ url = BootLoader.findResource(name);
+ }
+ if (url == null) {
+ url = findResource(name);
+ }
+ return url;
+ }
+
+ /**
+ * Finds all the resources with the given name. A resource is some data
+ * (images, audio, text, etc) that can be accessed by class code in a way
+ * that is independent of the location of the code.
+ *
+ * <p> The name of a resource is a {@code /}-separated path name that
+ * identifies the resource. </p>
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally (even if the caller of this method is in the
+ * same module as the resource). </p>
+ *
+ * @implSpec The default implementation will first search the parent class
+ * loader for the resource; if the parent is {@code null} the path of the
+ * class loader built into the virtual machine is searched. It then
+ * invokes {@link #findResources(String)} to find the resources with the
+ * name in this class loader. It returns an enumeration whose elements
+ * are the URLs found by searching the parent class loader followed by
+ * the elements found with {@code findResources}.
+ *
+ * @apiNote Where several modules are defined to the same class loader,
+ * and where more than one module contains a resource with the given name,
+ * then the ordering is not specified and may be very unpredictable.
+ * When overriding this method it is recommended that an
+ * implementation ensures that any delegation is consistent with the {@link
+ * #getResource(java.lang.String) getResource(String)} method. This should
+ * ensure that the first element returned by the Enumeration's
+ * {@code nextElement} method is the same resource that the
+ * {@code getResource(String)} method would return.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An enumeration of {@link java.net.URL URL} objects for
+ * the resource. If no resources could be found, the enumeration
+ * will be empty. Resources for which a {@code URL} cannot be
+ * constructed, are in package that is not opened unconditionally,
+ * or access to the resource is denied by the security manager,
+ * are not returned in the enumeration.
+ *
+ * @throws IOException
+ * If I/O errors occur
+ * @throws NullPointerException If {@code name} is {@code null}
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ */
+ public Enumeration<URL> getResources(String name) throws IOException {
+ Objects.requireNonNull(name);
+ @SuppressWarnings("unchecked")
+ Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
+ if (parent != null) {
+ tmp[0] = parent.getResources(name);
+ } else {
+ tmp[0] = BootLoader.findResources(name);
+ }
+ tmp[1] = findResources(name);
+
+ return new CompoundEnumeration<>(tmp);
+ }
+
+ /**
+ * Returns a stream whose elements are the URLs of all the resources with
+ * the given name. A resource is some data (images, audio, text, etc) that
+ * can be accessed by class code in a way that is independent of the
+ * location of the code.
+ *
+ * <p> The name of a resource is a {@code /}-separated path name that
+ * identifies the resource.
+ *
+ * <p> The resources will be located when the returned stream is evaluated.
+ * If the evaluation results in an {@code IOException} then the I/O
+ * exception is wrapped in an {@link UncheckedIOException} that is then
+ * thrown.
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally (even if the caller of this method is in the
+ * same module as the resource). </p>
+ *
+ * @implSpec The default implementation invokes {@link #getResources(String)
+ * getResources} to find all the resources with the given name and returns
+ * a stream with the elements in the enumeration as the source.
+ *
+ * @apiNote When overriding this method it is recommended that an
+ * implementation ensures that any delegation is consistent with the {@link
+ * #getResource(java.lang.String) getResource(String)} method. This should
+ * ensure that the first element returned by the stream is the same
+ * resource that the {@code getResource(String)} method would return.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return A stream of resource {@link java.net.URL URL} objects. If no
+ * resources could be found, the stream will be empty. Resources
+ * for which a {@code URL} cannot be constructed, are in a package
+ * that is not opened unconditionally, or access to the resource
+ * is denied by the security manager, will not be in the stream.
+ *
+ * @throws NullPointerException If {@code name} is {@code null}
+ *
+ * @since 9
+ */
+ public Stream<URL> resources(String name) {
+ Objects.requireNonNull(name);
+ int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
+ Supplier<Spliterator<URL>> si = () -> {
+ try {
+ return Spliterators.spliteratorUnknownSize(
+ getResources(name).asIterator(), characteristics);
+ } catch (IOException e) {
+ throw new UncheckedIOException(e);
+ }
+ };
+ return StreamSupport.stream(si, characteristics, false);
+ }
+
+ /**
+ * Finds the resource with the given name. Class loader implementations
+ * should override this method.
+ *
+ * <p> For resources in named modules then the method must implement the
+ * rules for encapsulation specified in the {@code Module} {@link
+ * Module#getResourceAsStream getResourceAsStream} method. Additionally,
+ * it must not find non-"{@code .class}" resources in packages of named
+ * modules unless the package is {@link Module#isOpen(String) opened}
+ * unconditionally. </p>
+ *
+ * @implSpec The default implementation returns {@code null}.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return {@code URL} object for reading the resource; {@code null} if
+ * the resource could not be found, a {@code URL} could not be
+ * constructed to locate the resource, the resource is in a package
+ * that is not opened unconditionally, or access to the resource is
+ * denied by the security manager.
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ */
+ protected URL findResource(String name) {
+ return null;
+ }
+
+ /**
+ * Returns an enumeration of {@link java.net.URL URL} objects
+ * representing all the resources with the given name. Class loader
+ * implementations should override this method.
+ *
+ * <p> For resources in named modules then the method must implement the
+ * rules for encapsulation specified in the {@code Module} {@link
+ * Module#getResourceAsStream getResourceAsStream} method. Additionally,
+ * it must not find non-"{@code .class}" resources in packages of named
+ * modules unless the package is {@link Module#isOpen(String) opened}
+ * unconditionally. </p>
+ *
+ * @implSpec The default implementation returns an enumeration that
+ * contains no elements.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An enumeration of {@link java.net.URL URL} objects for
+ * the resource. If no resources could be found, the enumeration
+ * will be empty. Resources for which a {@code URL} cannot be
+ * constructed, are in a package that is not opened unconditionally,
+ * or access to the resource is denied by the security manager,
+ * are not returned in the enumeration.
+ *
+ * @throws IOException
+ * If I/O errors occur
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ */
+ protected Enumeration<URL> findResources(String name) throws IOException {
+ return Collections.emptyEnumeration();
+ }
+
+ /**
+ * Registers the caller as
+ * {@linkplain #isRegisteredAsParallelCapable() parallel capable}.
+ * The registration succeeds if and only if all of the following
+ * conditions are met:
+ * <ol>
+ * <li> no instance of the caller has been created</li>
+ * <li> all of the super classes (except class Object) of the caller are
+ * registered as parallel capable</li>
+ * </ol>
+ * <p>Note that once a class loader is registered as parallel capable, there
+ * is no way to change it back.</p>
+ *
+ * @return {@code true} if the caller is successfully registered as
+ * parallel capable and {@code false} if otherwise.
+ *
+ * @see #isRegisteredAsParallelCapable()
+ *
+ * @since 1.7
+ */
+ @CallerSensitive
+ protected static boolean registerAsParallelCapable() {
+ Class<? extends ClassLoader> callerClass =
+ Reflection.getCallerClass().asSubclass(ClassLoader.class);
+ return ParallelLoaders.register(callerClass);
+ }
+
+ /**
+ * Returns {@code true} if this class loader is registered as
+ * {@linkplain #registerAsParallelCapable parallel capable}, otherwise
+ * {@code false}.
+ *
+ * @return {@code true} if this class loader is parallel capable,
+ * otherwise {@code false}.
+ *
+ * @see #registerAsParallelCapable()
+ *
+ * @since 9
+ */
+ public final boolean isRegisteredAsParallelCapable() {
+ return ParallelLoaders.isRegistered(this.getClass());
+ }
+
+ /**
+ * Find a resource of the specified name from the search path used to load
+ * classes. This method locates the resource through the system class
+ * loader (see {@link #getSystemClassLoader()}).
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally. </p>
+ *
+ * @param name
+ * The resource name
+ *
+ * @return A {@link java.net.URL URL} to the resource; {@code
+ * null} if the resource could not be found, a URL could not be
+ * constructed to locate the resource, the resource is in a package
+ * that is not opened unconditionally or access to the resource is
+ * denied by the security manager.
+ *
+ * @since 1.1
+ * @revised 9
+ * @spec JPMS
+ */
+ public static URL getSystemResource(String name) {
+ return getSystemClassLoader().getResource(name);
+ }
+
+ /**
+ * Finds all resources of the specified name from the search path used to
+ * load classes. The resources thus found are returned as an
+ * {@link java.util.Enumeration Enumeration} of {@link
+ * java.net.URL URL} objects.
+ *
+ * <p> The search order is described in the documentation for {@link
+ * #getSystemResource(String)}. </p>
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally. </p>
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An enumeration of {@link java.net.URL URL} objects for
+ * the resource. If no resources could be found, the enumeration
+ * will be empty. Resources for which a {@code URL} cannot be
+ * constructed, are in a package that is not opened unconditionally,
+ * or access to the resource is denied by the security manager,
+ * are not returned in the enumeration.
+ *
+ * @throws IOException
+ * If I/O errors occur
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ */
+ public static Enumeration<URL> getSystemResources(String name)
+ throws IOException
+ {
+ return getSystemClassLoader().getResources(name);
+ }
+
+ /**
+ * Returns an input stream for reading the specified resource.
+ *
+ * <p> The search order is described in the documentation for {@link
+ * #getResource(String)}. </p>
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally. </p>
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An input stream for reading the resource; {@code null} if the
+ * resource could not be found, the resource is in a package that
+ * is not opened unconditionally, or access to the resource is
+ * denied by the security manager.
+ *
+ * @throws NullPointerException If {@code name} is {@code null}
+ *
+ * @since 1.1
+ * @revised 9
+ * @spec JPMS
+ */
+ public InputStream getResourceAsStream(String name) {
+ Objects.requireNonNull(name);
+ URL url = getResource(name);
+ try {
+ return url != null ? url.openStream() : null;
+ } catch (IOException e) {
+ return null;
+ }
+ }
+
+ /**
+ * Open for reading, a resource of the specified name from the search path
+ * used to load classes. This method locates the resource through the
+ * system class loader (see {@link #getSystemClassLoader()}).
+ *
+ * <p> Resources in named modules are subject to the encapsulation rules
+ * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}.
+ * Additionally, and except for the special case where the resource has a
+ * name ending with "{@code .class}", this method will only find resources in
+ * packages of named modules when the package is {@link Module#isOpen(String)
+ * opened} unconditionally. </p>
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An input stream for reading the resource; {@code null} if the
+ * resource could not be found, the resource is in a package that
+ * is not opened unconditionally, or access to the resource is
+ * denied by the security manager.
+ *
+ * @since 1.1
+ * @revised 9
+ * @spec JPMS
+ */
+ public static InputStream getSystemResourceAsStream(String name) {
+ URL url = getSystemResource(name);
+ try {
+ return url != null ? url.openStream() : null;
+ } catch (IOException e) {
+ return null;
+ }
+ }
+
+
+ // -- Hierarchy --
+
+ /**
+ * Returns the parent class loader for delegation. Some implementations may
+ * use {@code null} to represent the bootstrap class loader. This method
+ * will return {@code null} in such implementations if this class loader's
+ * parent is the bootstrap class loader.
+ *
+ * @return The parent {@code ClassLoader}
+ *
+ * @throws SecurityException
+ * If a security manager is present, and the caller's class loader
+ * is not {@code null} and is not an ancestor of this class loader,
+ * and the caller does not have the
+ * {@link RuntimePermission}{@code ("getClassLoader")}
+ *
+ * @since 1.2
+ */
+ @CallerSensitive
+ public final ClassLoader getParent() {
+ if (parent == null)
+ return null;
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ // Check access to the parent class loader
+ // If the caller's class loader is same as this class loader,
+ // permission check is performed.
+ checkClassLoaderPermission(parent, Reflection.getCallerClass());
+ }
+ return parent;
+ }
+
+ /**
+ * Returns the unnamed {@code Module} for this class loader.
+ *
+ * @return The unnamed Module for this class loader
+ *
+ * @see Module#isNamed()
+ * @since 9
+ * @spec JPMS
+ */
+ public final Module getUnnamedModule() {
+ return unnamedModule;
+ }
+
+ /**
+ * Returns the platform class loader for delegation. All
+ * <a href="#builtinLoaders">platform classes</a> are visible to
+ * the platform class loader.
+ *
+ * @implNote The name of the builtin platform class loader is
+ * {@code "platform"}.
+ *
+ * @return The platform {@code ClassLoader}.
+ *
+ * @throws SecurityException
+ * If a security manager is present, and the caller's class loader is
+ * not {@code null}, and the caller's class loader is not the same
+ * as or an ancestor of the platform class loader,
+ * and the caller does not have the
+ * {@link RuntimePermission}{@code ("getClassLoader")}
+ *
+ * @since 9
+ * @spec JPMS
+ */
+ @CallerSensitive
+ public static ClassLoader getPlatformClassLoader() {
+ SecurityManager sm = System.getSecurityManager();
+ ClassLoader loader = getBuiltinPlatformClassLoader();
+ if (sm != null) {
+ checkClassLoaderPermission(loader, Reflection.getCallerClass());
+ }
+ return loader;
+ }
+
+ /**
+ * Returns the system class loader for delegation. This is the default
+ * delegation parent for new {@code ClassLoader} instances, and is
+ * typically the class loader used to start the application.
+ *
+ * <p> This method is first invoked early in the runtime's startup
+ * sequence, at which point it creates the system class loader. This
+ * class loader will be the context class loader for the main application
+ * thread (for example, the thread that invokes the {@code main} method of
+ * the main class).
+ *
+ * <p> The default system class loader is an implementation-dependent
+ * instance of this class.
+ *
+ * <p> If the system property "{@code java.system.class.loader}" is defined
+ * when this method is first invoked then the value of that property is
+ * taken to be the name of a class that will be returned as the system
+ * class loader. The class is loaded using the default system class loader
+ * and must define a public constructor that takes a single parameter of
+ * type {@code ClassLoader} which is used as the delegation parent. An
+ * instance is then created using this constructor with the default system
+ * class loader as the parameter. The resulting class loader is defined
+ * to be the system class loader. During construction, the class loader
+ * should take great care to avoid calling {@code getSystemClassLoader()}.
+ * If circular initialization of the system class loader is detected then
+ * an unspecified error or exception is thrown.
+ *
+ * @implNote The system property to override the system class loader is not
+ * examined until the VM is almost fully initialized. Code that executes
+ * this method during startup should take care not to cache the return
+ * value until the system is fully initialized.
+ *
+ * <p> The name of the built-in system class loader is {@code "app"}.
+ * The class path used by the built-in system class loader is determined
+ * by the system property "{@code java.class.path}" during early
+ * initialization of the VM. If the system property is not defined,
+ * or its value is an empty string, then there is no class path
+ * when the initial module is a module on the application module path,
+ * i.e. <em>a named module</em>. If the initial module is not on
+ * the application module path then the class path defaults to
+ * the current working directory.
+ *
+ * @return The system {@code ClassLoader} for delegation
+ *
+ * @throws SecurityException
+ * If a security manager is present, and the caller's class loader
+ * is not {@code null} and is not the same as or an ancestor of the
+ * system class loader, and the caller does not have the
+ * {@link RuntimePermission}{@code ("getClassLoader")}
+ *
+ * @throws IllegalStateException
+ * If invoked recursively during the construction of the class
+ * loader specified by the "{@code java.system.class.loader}"
+ * property.
+ *
+ * @throws Error
+ * If the system property "{@code java.system.class.loader}"
+ * is defined but the named class could not be loaded, the
+ * provider class does not define the required constructor, or an
+ * exception is thrown by that constructor when it is invoked. The
+ * underlying cause of the error can be retrieved via the
+ * {@link Throwable#getCause()} method.
+ *
+ * @revised 1.4
+ * @revised 9
+ * @spec JPMS
+ */
+ @CallerSensitive
+ public static ClassLoader getSystemClassLoader() {
+ switch (VM.initLevel()) {
+ case 0:
+ case 1:
+ case 2:
+ // the system class loader is the built-in app class loader during startup
+ return getBuiltinAppClassLoader();
+ case 3:
+ String msg = "getSystemClassLoader should only be called after VM booted";
+ throw new InternalError(msg);
+ case 4:
+ // system fully initialized
+ assert VM.isBooted() && scl != null;
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ checkClassLoaderPermission(scl, Reflection.getCallerClass());
+ }
+ return scl;
+ default:
+ throw new InternalError("should not reach here");
+ }
+ }
+
+ static ClassLoader getBuiltinPlatformClassLoader() {
+ return ClassLoaders.platformClassLoader();
+ }
+
+ static ClassLoader getBuiltinAppClassLoader() {
+ return ClassLoaders.appClassLoader();
+ }
+
+ /*
+ * Initialize the system class loader that may be a custom class on the
+ * application class path or application module path.
+ *
+ * @see java.lang.System#initPhase3
+ */
+ static synchronized ClassLoader initSystemClassLoader() {
+ if (VM.initLevel() != 3) {
+ throw new InternalError("system class loader cannot be set at initLevel " +
+ VM.initLevel());
+ }
+
+ // detect recursive initialization
+ if (scl != null) {
+ throw new IllegalStateException("recursive invocation");
+ }
+
+ ClassLoader builtinLoader = getBuiltinAppClassLoader();
+
+ // All are privileged frames. No need to call doPrivileged.
+ String cn = System.getProperty("java.system.class.loader");
+ if (cn != null) {
+ try {
+ // custom class loader is only supported to be loaded from unnamed module
+ Constructor<?> ctor = Class.forName(cn, false, builtinLoader)
+ .getDeclaredConstructor(ClassLoader.class);
+ scl = (ClassLoader) ctor.newInstance(builtinLoader);
+ } catch (Exception e) {
+ throw new Error(e);
+ }
+ } else {
+ scl = builtinLoader;
+ }
+ return scl;
+ }
+
+ // Returns true if the specified class loader can be found in this class
+ // loader's delegation chain.
+ boolean isAncestor(ClassLoader cl) {
+ ClassLoader acl = this;
+ do {
+ acl = acl.parent;
+ if (cl == acl) {
+ return true;
+ }
+ } while (acl != null);
+ return false;
+ }
+
+ // Tests if class loader access requires "getClassLoader" permission
+ // check. A class loader 'from' can access class loader 'to' if
+ // class loader 'from' is same as class loader 'to' or an ancestor
+ // of 'to'. The class loader in a system domain can access
+ // any class loader.
+ private static boolean needsClassLoaderPermissionCheck(ClassLoader from,
+ ClassLoader to)
+ {
+ if (from == to)
+ return false;
+
+ if (from == null)
+ return false;
+
+ return !to.isAncestor(from);
+ }
+
+ // Returns the class's class loader, or null if none.
+ static ClassLoader getClassLoader(Class<?> caller) {
+ // This can be null if the VM is requesting it
+ if (caller == null) {
+ return null;
+ }
+ // Circumvent security check since this is package-private
+ return caller.getClassLoader0();
+ }
+
+ /*
+ * Checks RuntimePermission("getClassLoader") permission
+ * if caller's class loader is not null and caller's class loader
+ * is not the same as or an ancestor of the given cl argument.
+ */
+ static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) {
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ // caller can be null if the VM is requesting it
+ ClassLoader ccl = getClassLoader(caller);
+ if (needsClassLoaderPermissionCheck(ccl, cl)) {
+ sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
+ }
+ }
+ }
+
+ // The system class loader
+ // @GuardedBy("ClassLoader.class")
+ private static volatile ClassLoader scl;
+
+ // -- Package --
+
+ /**
+ * Define a Package of the given Class object.
+ *
+ * If the given class represents an array type, a primitive type or void,
+ * this method returns {@code null}.
+ *
+ * This method does not throw IllegalArgumentException.
+ */
+ Package definePackage(Class<?> c) {
+ if (c.isPrimitive() || c.isArray()) {
+ return null;
+ }
+
+ return definePackage(c.getPackageName(), c.getModule());
+ }
+
+ /**
+ * Defines a Package of the given name and module
+ *
+ * This method does not throw IllegalArgumentException.
+ *
+ * @param name package name
+ * @param m module
+ */
+ Package definePackage(String name, Module m) {
+ if (name.isEmpty() && m.isNamed()) {
+ throw new InternalError("unnamed package in " + m);
+ }
+
+ // check if Package object is already defined
+ NamedPackage pkg = packages.get(name);
+ if (pkg instanceof Package)
+ return (Package)pkg;
+
+ return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m));
+ }
+
+ /*
+ * Returns a Package object for the named package
+ */
+ private Package toPackage(String name, NamedPackage p, Module m) {
+ // define Package object if the named package is not yet defined
+ if (p == null)
+ return NamedPackage.toPackage(name, m);
+
+ // otherwise, replace the NamedPackage object with Package object
+ if (p instanceof Package)
+ return (Package)p;
+
+ return NamedPackage.toPackage(p.packageName(), p.module());
+ }
+
+ /**
+ * Defines a package by <a href="#name">name</a> in this {@code ClassLoader}.
+ * <p>
+ * <a href="#name">Package names</a> must be unique within a class loader and
+ * cannot be redefined or changed once created.
+ * <p>
+ * If a class loader wishes to define a package with specific properties,
+ * such as version information, then the class loader should call this
+ * {@code definePackage} method before calling {@code defineClass}.
+ * Otherwise, the
+ * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass}
+ * method will define a package in this class loader corresponding to the package
+ * of the newly defined class; the properties of this defined package are
+ * specified by {@link Package}.
+ *
+ * @apiNote
+ * A class loader that wishes to define a package for classes in a JAR
+ * typically uses the specification and implementation titles, versions, and
+ * vendors from the JAR's manifest. If the package is specified as
+ * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest,
+ * the {@code URL} of the JAR file is typically used as the {@code sealBase}.
+ * If classes of package {@code 'p'} defined by this class loader
+ * are loaded from multiple JARs, the {@code Package} object may contain
+ * different information depending on the first class of package {@code 'p'}
+ * defined and which JAR's manifest is read first to explicitly define
+ * package {@code 'p'}.
+ *
+ * <p> It is strongly recommended that a class loader does not call this
+ * method to explicitly define packages in <em>named modules</em>; instead,
+ * the package will be automatically defined when a class is {@linkplain
+ * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}.
+ * If it is desirable to define {@code Package} explicitly, it should ensure
+ * that all packages in a named module are defined with the properties
+ * specified by {@link Package}. Otherwise, some {@code Package} objects
+ * in a named module may be for example sealed with different seal base.
+ *
+ * @param name
+ * The <a href="#name">package name</a>
+ *
+ * @param specTitle
+ * The specification title
+ *
+ * @param specVersion
+ * The specification version
+ *
+ * @param specVendor
+ * The specification vendor
+ *
+ * @param implTitle
+ * The implementation title
+ *
+ * @param implVersion
+ * The implementation version
+ *
+ * @param implVendor
+ * The implementation vendor
+ *
+ * @param sealBase
+ * If not {@code null}, then this package is sealed with
+ * respect to the given code source {@link java.net.URL URL}
+ * object. Otherwise, the package is not sealed.
+ *
+ * @return The newly defined {@code Package} object
+ *
+ * @throws NullPointerException
+ * if {@code name} is {@code null}.
+ *
+ * @throws IllegalArgumentException
+ * if a package of the given {@code name} is already
+ * defined by this class loader
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ *
+ * @see <a href="{@docRoot}/../specs/jar/jar.html#sealing">
+ * The JAR File Specification: Package Sealing</a>
+ */
+ protected Package definePackage(String name, String specTitle,
+ String specVersion, String specVendor,
+ String implTitle, String implVersion,
+ String implVendor, URL sealBase)
+ {
+ Objects.requireNonNull(name);
+
+ // definePackage is not final and may be overridden by custom class loader
+ Package p = new Package(name, specTitle, specVersion, specVendor,
+ implTitle, implVersion, implVendor,
+ sealBase, this);
+
+ if (packages.putIfAbsent(name, p) != null)
+ throw new IllegalArgumentException(name);
+
+ return p;
+ }
+
+ /**
+ * Returns a {@code Package} of the given <a href="#name">name</a> that has been
+ * defined by this class loader.
+ *
+ * @param name The <a href="#name">package name</a>
+ *
+ * @return The {@code Package} of the given name defined by this class loader,
+ * or {@code null} if not found
+ *
+ * @throws NullPointerException
+ * if {@code name} is {@code null}.
+ *
+ * @since 9
+ * @spec JPMS
+ */
+ public final Package getDefinedPackage(String name) {
+ Objects.requireNonNull(name, "name cannot be null");
+
+ NamedPackage p = packages.get(name);
+ if (p == null)
+ return null;
+
+ return definePackage(name, p.module());
+ }
+
+ /**
+ * Returns all of the {@code Package}s defined by this class loader.
+ * The returned array has no duplicated {@code Package}s of the same name.
+ *
+ * @apiNote This method returns an array rather than a {@code Set} or {@code Stream}
+ * for consistency with the existing {@link #getPackages} method.
+ *
+ * @return The array of {@code Package} objects defined by this class loader;
+ * or an zero length array if no package has been defined by this class loader.
+ *
+ * @since 9
+ * @spec JPMS
+ */
+ public final Package[] getDefinedPackages() {
+ return packages().toArray(Package[]::new);
+ }
+
+ /**
+ * Finds a package by <a href="#name">name</a> in this class loader and its ancestors.
+ * <p>
+ * If this class loader defines a {@code Package} of the given name,
+ * the {@code Package} is returned. Otherwise, the ancestors of
+ * this class loader are searched recursively (parent by parent)
+ * for a {@code Package} of the given name.
+ *
+ * @apiNote The {@link #getPlatformClassLoader() platform class loader}
+ * may delegate to the application class loader but the application class
+ * loader is not its ancestor. When invoked on the platform class loader,
+ * this method will not find packages defined to the application
+ * class loader.
+ *
+ * @param name
+ * The <a href="#name">package name</a>
+ *
+ * @return The {@code Package} corresponding to the given name defined by
+ * this class loader or its ancestors, or {@code null} if not found.
+ *
+ * @throws NullPointerException
+ * if {@code name} is {@code null}.
+ *
+ * @deprecated
+ * If multiple class loaders delegate to each other and define classes
+ * with the same package name, and one such loader relies on the lookup
+ * behavior of {@code getPackage} to return a {@code Package} from
+ * a parent loader, then the properties exposed by the {@code Package}
+ * may not be as expected in the rest of the program.
+ * For example, the {@code Package} will only expose annotations from the
+ * {@code package-info.class} file defined by the parent loader, even if
+ * annotations exist in a {@code package-info.class} file defined by
+ * a child loader. A more robust approach is to use the
+ * {@link ClassLoader#getDefinedPackage} method which returns
+ * a {@code Package} for the specified class loader.
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ */
+ @Deprecated(since="9")
+ protected Package getPackage(String name) {
+ Package pkg = getDefinedPackage(name);
+ if (pkg == null) {
+ if (parent != null) {
+ pkg = parent.getPackage(name);
+ } else {
+ pkg = BootLoader.getDefinedPackage(name);
+ }
+ }
+ return pkg;
+ }
+
+ /**
+ * Returns all of the {@code Package}s defined by this class loader
+ * and its ancestors. The returned array may contain more than one
+ * {@code Package} object of the same package name, each defined by
+ * a different class loader in the class loader hierarchy.
+ *
+ * @apiNote The {@link #getPlatformClassLoader() platform class loader}
+ * may delegate to the application class loader. In other words,
+ * packages in modules defined to the application class loader may be
+ * visible to the platform class loader. On the other hand,
+ * the application class loader is not its ancestor and hence
+ * when invoked on the platform class loader, this method will not
+ * return any packages defined to the application class loader.
+ *
+ * @return The array of {@code Package} objects defined by this
+ * class loader and its ancestors
+ *
+ * @since 1.2
+ * @revised 9
+ * @spec JPMS
+ */
+ protected Package[] getPackages() {
+ Stream<Package> pkgs = packages();
+ ClassLoader ld = parent;
+ while (ld != null) {
+ pkgs = Stream.concat(ld.packages(), pkgs);
+ ld = ld.parent;
+ }
+ return Stream.concat(BootLoader.packages(), pkgs)
+ .toArray(Package[]::new);
+ }
+
+
+
+ // package-private
+
+ /**
+ * Returns a stream of Packages defined in this class loader
+ */
+ Stream<Package> packages() {
+ return packages.values().stream()
+ .map(p -> definePackage(p.packageName(), p.module()));
+ }
+
+ // -- Native library access --
+
+ /**
+ * Returns the absolute path name of a native library. The VM invokes this
+ * method to locate the native libraries that belong to classes loaded with
+ * this class loader. If this method returns {@code null}, the VM
+ * searches the library along the path specified as the
+ * "{@code java.library.path}" property.
+ *
+ * @param libname
+ * The library name
+ *
+ * @return The absolute path of the native library
+ *
+ * @see System#loadLibrary(String)
+ * @see System#mapLibraryName(String)
+ *
+ * @since 1.2
+ */
+ protected String findLibrary(String libname) {
+ return null;
+ }
+
+ /**
+ * The inner class NativeLibrary denotes a loaded native library instance.
+ * Every classloader contains a vector of loaded native libraries in the
+ * private field {@code nativeLibraries}. The native libraries loaded
+ * into the system are entered into the {@code systemNativeLibraries}
+ * vector.
+ *
+ * <p> Every native library requires a particular version of JNI. This is
+ * denoted by the private {@code jniVersion} field. This field is set by
+ * the VM when it loads the library, and used by the VM to pass the correct
+ * version of JNI to the native methods. </p>
+ *
+ * @see ClassLoader
+ * @since 1.2
+ */
+ static class NativeLibrary {
+ // opaque handle to native library, used in native code.
+ long handle;
+ // the version of JNI environment the native library requires.
+ private int jniVersion;
+ // the class from which the library is loaded, also indicates
+ // the loader this native library belongs.
+ private final Class<?> fromClass;
+ // the canonicalized name of the native library.
+ // or static library name
+ String name;
+ // Indicates if the native library is linked into the VM
+ boolean isBuiltin;
+ // Indicates if the native library is loaded
+ boolean loaded;
+ native void load(String name, boolean isBuiltin);
+
+ native long find(String name);
+ native void unload(String name, boolean isBuiltin);
+
+ public NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
+ this.name = name;
+ this.fromClass = fromClass;
+ this.isBuiltin = isBuiltin;
+ }
+
+ @SuppressWarnings("deprecation")
+ protected void finalize() {
+ synchronized (loadedLibraryNames) {
+ if (fromClass.getClassLoader() != null && loaded) {
+ /* remove the native library name */
+ int size = loadedLibraryNames.size();
+ for (int i = 0; i < size; i++) {
+ if (name.equals(loadedLibraryNames.elementAt(i))) {
+ loadedLibraryNames.removeElementAt(i);
+ break;
+ }
+ }
+ /* unload the library. */
+ ClassLoader.nativeLibraryContext.push(this);
+ try {
+ unload(name, isBuiltin);
+ } finally {
+ ClassLoader.nativeLibraryContext.pop();
+ }
+ }
+ }
+ }
+ // Invoked in the VM to determine the context class in
+ // JNI_Load/JNI_Unload
+ static Class<?> getFromClass() {
+ return ClassLoader.nativeLibraryContext.peek().fromClass;
+ }
+ }
+
+ // All native library names we've loaded.
+ private static Vector<String> loadedLibraryNames = new Vector<>();
+
+ // Native libraries belonging to system classes.
+ private static Vector<NativeLibrary> systemNativeLibraries
+ = new Vector<>();
+
+ // Native libraries associated with the class loader.
+ private Vector<NativeLibrary> nativeLibraries = new Vector<>();
+
+ // native libraries being loaded/unloaded.
+ private static Stack<NativeLibrary> nativeLibraryContext = new Stack<>();
+
+ // The paths searched for libraries
+ private static String usr_paths[];
+ private static String sys_paths[];
+
+ private static String[] initializePath(String propName) {
+ String ldPath = System.getProperty(propName, "");
+ int ldLen = ldPath.length();
+ char ps = File.pathSeparatorChar;
+ int psCount = 0;
+
+ if (ClassLoaderHelper.allowsQuotedPathElements &&
+ ldPath.indexOf('\"') >= 0) {
+ // First, remove quotes put around quoted parts of paths.
+ // Second, use a quotation mark as a new path separator.
+ // This will preserve any quoted old path separators.
+ char[] buf = new char[ldLen];
+ int bufLen = 0;
+ for (int i = 0; i < ldLen; ++i) {
+ char ch = ldPath.charAt(i);
+ if (ch == '\"') {
+ while (++i < ldLen &&
+ (ch = ldPath.charAt(i)) != '\"') {
+ buf[bufLen++] = ch;
+ }
+ } else {
+ if (ch == ps) {
+ psCount++;
+ ch = '\"';
+ }
+ buf[bufLen++] = ch;
+ }
+ }
+ ldPath = new String(buf, 0, bufLen);
+ ldLen = bufLen;
+ ps = '\"';
+ } else {
+ for (int i = ldPath.indexOf(ps); i >= 0;
+ i = ldPath.indexOf(ps, i + 1)) {
+ psCount++;
+ }
+ }
+
+ String[] paths = new String[psCount + 1];
+ int pathStart = 0;
+ for (int j = 0; j < psCount; ++j) {
+ int pathEnd = ldPath.indexOf(ps, pathStart);
+ paths[j] = (pathStart < pathEnd) ?
+ ldPath.substring(pathStart, pathEnd) : ".";
+ pathStart = pathEnd + 1;
+ }
+ paths[psCount] = (pathStart < ldLen) ?
+ ldPath.substring(pathStart, ldLen) : ".";
+ return paths;
+ }
+
+ // Invoked in the java.lang.Runtime class to implement load and loadLibrary.
+ static void loadLibrary(Class<?> fromClass, String name,
+ boolean isAbsolute) {
+ ClassLoader loader =
+ (fromClass == null) ? null : fromClass.getClassLoader();
+ if (sys_paths == null) {
+ usr_paths = initializePath("java.library.path");
+ sys_paths = initializePath("sun.boot.library.path");
+ }
+ if (isAbsolute) {
+ if (loadLibrary0(fromClass, new File(name))) {
+ return;
+ }
+ throw new UnsatisfiedLinkError("Can't load library: " + name);
+ }
+ if (loader != null) {
+ String libfilename = loader.findLibrary(name);
+ if (libfilename != null) {
+ File libfile = new File(libfilename);
+ if (!libfile.isAbsolute()) {
+ throw new UnsatisfiedLinkError(
+ "ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
+ }
+ if (loadLibrary0(fromClass, libfile)) {
+ return;
+ }
+ throw new UnsatisfiedLinkError("Can't load " + libfilename);
+ }
+ }
+ for (String sys_path : sys_paths) {
+ File libfile = new File(sys_path, System.mapLibraryName(name));
+ if (loadLibrary0(fromClass, libfile)) {
+ return;
+ }
+ libfile = ClassLoaderHelper.mapAlternativeName(libfile);
+ if (libfile != null && loadLibrary0(fromClass, libfile)) {
+ return;
+ }
+ }
+ if (loader != null) {
+ for (String usr_path : usr_paths) {
+ File libfile = new File(usr_path, System.mapLibraryName(name));
+ if (loadLibrary0(fromClass, libfile)) {
+ return;
+ }
+ libfile = ClassLoaderHelper.mapAlternativeName(libfile);
+ if (libfile != null && loadLibrary0(fromClass, libfile)) {
+ return;
+ }
+ }
+ }
+ // Oops, it failed
+ throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
+ }
+
+ static native String findBuiltinLib(String name);
+
+ private static boolean loadLibrary0(Class<?> fromClass, final File file) {
+ // Check to see if we're attempting to access a static library
+ String name = findBuiltinLib(file.getName());
+ boolean isBuiltin = (name != null);
+ if (!isBuiltin) {
+ name = AccessController.doPrivileged(
+ new PrivilegedAction<>() {
+ public String run() {
+ try {
+ return file.exists() ? file.getCanonicalPath() : null;
+ } catch (IOException e) {
+ return null;
+ }
+ }
+ });
+ if (name == null) {
+ return false;
+ }
+ }
+ ClassLoader loader =
+ (fromClass == null) ? null : fromClass.getClassLoader();
+ Vector<NativeLibrary> libs =
+ loader != null ? loader.nativeLibraries : systemNativeLibraries;
+ synchronized (libs) {
+ int size = libs.size();
+ for (int i = 0; i < size; i++) {
+ NativeLibrary lib = libs.elementAt(i);
+ if (name.equals(lib.name)) {
+ return true;
+ }
+ }
+
+ synchronized (loadedLibraryNames) {
+ if (loadedLibraryNames.contains(name)) {
+ throw new UnsatisfiedLinkError
+ ("Native Library " +
+ name +
+ " already loaded in another classloader");
+ }
+ /* If the library is being loaded (must be by the same thread,
+ * because Runtime.load and Runtime.loadLibrary are
+ * synchronous). The reason is can occur is that the JNI_OnLoad
+ * function can cause another loadLibrary invocation.
+ *
+ * Thus we can use a static stack to hold the list of libraries
+ * we are loading.
+ *
+ * If there is a pending load operation for the library, we
+ * immediately return success; otherwise, we raise
+ * UnsatisfiedLinkError.
+ */
+ int n = nativeLibraryContext.size();
+ for (int i = 0; i < n; i++) {
+ NativeLibrary lib = nativeLibraryContext.elementAt(i);
+ if (name.equals(lib.name)) {
+ if (loader == lib.fromClass.getClassLoader()) {
+ return true;
+ } else {
+ throw new UnsatisfiedLinkError
+ ("Native Library " +
+ name +
+ " is being loaded in another classloader");
+ }
+ }
+ }
+ NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin);
+ nativeLibraryContext.push(lib);
+ try {
+ lib.load(name, isBuiltin);
+ } finally {
+ nativeLibraryContext.pop();
+ }
+ if (lib.loaded) {
+ loadedLibraryNames.addElement(name);
+ libs.addElement(lib);
+ return true;
+ }
+ return false;
+ }
+ }
+ }
+
+ // Invoked in the VM class linking code.
+ static long findNative(ClassLoader loader, String name) {
+ Vector<NativeLibrary> libs =
+ loader != null ? loader.nativeLibraries : systemNativeLibraries;
+ synchronized (libs) {
+ int size = libs.size();
+ for (int i = 0; i < size; i++) {
+ NativeLibrary lib = libs.elementAt(i);
+ long entry = lib.find(name);
+ if (entry != 0)
+ return entry;
+ }
+ }
+ return 0;
+ }
+
+
+ // -- Assertion management --
+
+ final Object assertionLock;
+
+ // The default toggle for assertion checking.
+ // @GuardedBy("assertionLock")
+ private boolean defaultAssertionStatus = false;
+
+ // Maps String packageName to Boolean package default assertion status Note
+ // that the default package is placed under a null map key. If this field
+ // is null then we are delegating assertion status queries to the VM, i.e.,
+ // none of this ClassLoader's assertion status modification methods have
+ // been invoked.
+ // @GuardedBy("assertionLock")
+ private Map<String, Boolean> packageAssertionStatus = null;
+
+ // Maps String fullyQualifiedClassName to Boolean assertionStatus If this
+ // field is null then we are delegating assertion status queries to the VM,
+ // i.e., none of this ClassLoader's assertion status modification methods
+ // have been invoked.
+ // @GuardedBy("assertionLock")
+ Map<String, Boolean> classAssertionStatus = null;
+
+ /**
+ * Sets the default assertion status for this class loader. This setting
+ * determines whether classes loaded by this class loader and initialized
+ * in the future will have assertions enabled or disabled by default.
+ * This setting may be overridden on a per-package or per-class basis by
+ * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link
+ * #setClassAssertionStatus(String, boolean)}.
+ *
+ * @param enabled
+ * {@code true} if classes loaded by this class loader will
+ * henceforth have assertions enabled by default, {@code false}
+ * if they will have assertions disabled by default.
+ *
+ * @since 1.4
+ */
+ public void setDefaultAssertionStatus(boolean enabled) {
+ synchronized (assertionLock) {
+ if (classAssertionStatus == null)
+ initializeJavaAssertionMaps();
+
+ defaultAssertionStatus = enabled;
+ }
+ }
+
+ /**
+ * Sets the package default assertion status for the named package. The
+ * package default assertion status determines the assertion status for
+ * classes initialized in the future that belong to the named package or
+ * any of its "subpackages".
+ *
+ * <p> A subpackage of a package named p is any package whose name begins
+ * with "{@code p.}". For example, {@code javax.swing.text} is a
+ * subpackage of {@code javax.swing}, and both {@code java.util} and
+ * {@code java.lang.reflect} are subpackages of {@code java}.
+ *
+ * <p> In the event that multiple package defaults apply to a given class,
+ * the package default pertaining to the most specific package takes
+ * precedence over the others. For example, if {@code javax.lang} and
+ * {@code javax.lang.reflect} both have package defaults associated with
+ * them, the latter package default applies to classes in
+ * {@code javax.lang.reflect}.
+ *
+ * <p> Package defaults take precedence over the class loader's default
+ * assertion status, and may be overridden on a per-class basis by invoking
+ * {@link #setClassAssertionStatus(String, boolean)}. </p>
+ *
+ * @param packageName
+ * The name of the package whose package default assertion status
+ * is to be set. A {@code null} value indicates the unnamed
+ * package that is "current"
+ * (see section 7.4.2 of
+ * <cite>The Java™ Language Specification</cite>.)
+ *
+ * @param enabled
+ * {@code true} if classes loaded by this classloader and
+ * belonging to the named package or any of its subpackages will
+ * have assertions enabled by default, {@code false} if they will
+ * have assertions disabled by default.
+ *
+ * @since 1.4
+ */
+ public void setPackageAssertionStatus(String packageName,
+ boolean enabled) {
+ synchronized (assertionLock) {
+ if (packageAssertionStatus == null)
+ initializeJavaAssertionMaps();
+
+ packageAssertionStatus.put(packageName, enabled);
+ }
+ }
+
+ /**
+ * Sets the desired assertion status for the named top-level class in this
+ * class loader and any nested classes contained therein. This setting
+ * takes precedence over the class loader's default assertion status, and
+ * over any applicable per-package default. This method has no effect if
+ * the named class has already been initialized. (Once a class is
+ * initialized, its assertion status cannot change.)
+ *
+ * <p> If the named class is not a top-level class, this invocation will
+ * have no effect on the actual assertion status of any class. </p>
+ *
+ * @param className
+ * The fully qualified class name of the top-level class whose
+ * assertion status is to be set.
+ *
+ * @param enabled
+ * {@code true} if the named class is to have assertions
+ * enabled when (and if) it is initialized, {@code false} if the
+ * class is to have assertions disabled.
+ *
+ * @since 1.4
+ */
+ public void setClassAssertionStatus(String className, boolean enabled) {
+ synchronized (assertionLock) {
+ if (classAssertionStatus == null)
+ initializeJavaAssertionMaps();
+
+ classAssertionStatus.put(className, enabled);
+ }
+ }
+
+ /**
+ * Sets the default assertion status for this class loader to
+ * {@code false} and discards any package defaults or class assertion
+ * status settings associated with the class loader. This method is
+ * provided so that class loaders can be made to ignore any command line or
+ * persistent assertion status settings and "start with a clean slate."
+ *
+ * @since 1.4
+ */
+ public void clearAssertionStatus() {
+ /*
+ * Whether or not "Java assertion maps" are initialized, set
+ * them to empty maps, effectively ignoring any present settings.
+ */
+ synchronized (assertionLock) {
+ classAssertionStatus = new HashMap<>();
+ packageAssertionStatus = new HashMap<>();
+ defaultAssertionStatus = false;
+ }
+ }
+
+ /**
+ * Returns the assertion status that would be assigned to the specified
+ * class if it were to be initialized at the time this method is invoked.
+ * If the named class has had its assertion status set, the most recent
+ * setting will be returned; otherwise, if any package default assertion
+ * status pertains to this class, the most recent setting for the most
+ * specific pertinent package default assertion status is returned;
+ * otherwise, this class loader's default assertion status is returned.
+ * </p>
+ *
+ * @param className
+ * The fully qualified class name of the class whose desired
+ * assertion status is being queried.
+ *
+ * @return The desired assertion status of the specified class.
+ *
+ * @see #setClassAssertionStatus(String, boolean)
+ * @see #setPackageAssertionStatus(String, boolean)
+ * @see #setDefaultAssertionStatus(boolean)
+ *
+ * @since 1.4
+ */
+ boolean desiredAssertionStatus(String className) {
+ synchronized (assertionLock) {
+ // assert classAssertionStatus != null;
+ // assert packageAssertionStatus != null;
+
+ // Check for a class entry
+ Boolean result = classAssertionStatus.get(className);
+ if (result != null)
+ return result.booleanValue();
+
+ // Check for most specific package entry
+ int dotIndex = className.lastIndexOf('.');
+ if (dotIndex < 0) { // default package
+ result = packageAssertionStatus.get(null);
+ if (result != null)
+ return result.booleanValue();
+ }
+ while(dotIndex > 0) {
+ className = className.substring(0, dotIndex);
+ result = packageAssertionStatus.get(className);
+ if (result != null)
+ return result.booleanValue();
+ dotIndex = className.lastIndexOf('.', dotIndex-1);
+ }
+
+ // Return the classloader default
+ return defaultAssertionStatus;
+ }
+ }
+
+ // Set up the assertions with information provided by the VM.
+ // Note: Should only be called inside a synchronized block
+ private void initializeJavaAssertionMaps() {
+ // assert Thread.holdsLock(assertionLock);
+
+ classAssertionStatus = new HashMap<>();
+ packageAssertionStatus = new HashMap<>();
+ AssertionStatusDirectives directives = retrieveDirectives();
+
+ for(int i = 0; i < directives.classes.length; i++)
+ classAssertionStatus.put(directives.classes[i],
+ directives.classEnabled[i]);
+
+ for(int i = 0; i < directives.packages.length; i++)
+ packageAssertionStatus.put(directives.packages[i],
+ directives.packageEnabled[i]);
+
+ defaultAssertionStatus = directives.deflt;
+ }
+
+ // Retrieves the assertion directives from the VM.
+ private static native AssertionStatusDirectives retrieveDirectives();
+
+
+ // -- Misc --
+
+ /**
+ * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s)
+ * associated with this ClassLoader, creating it if it doesn't already exist.
+ */
+ ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() {
+ ConcurrentHashMap<?, ?> map = classLoaderValueMap;
+ if (map == null) {
+ map = new ConcurrentHashMap<>();
+ boolean set = trySetObjectField("classLoaderValueMap", map);
+ if (!set) {
+ // beaten by someone else
+ map = classLoaderValueMap;
+ }
+ }
+ return map;
+ }
+
+ // the storage for ClassLoaderValue(s) associated with this ClassLoader
+ private volatile ConcurrentHashMap<?, ?> classLoaderValueMap;
+
+ /**
+ * Attempts to atomically set a volatile field in this object. Returns
+ * {@code true} if not beaten by another thread. Avoids the use of
+ * AtomicReferenceFieldUpdater in this class.
+ */
+ private boolean trySetObjectField(String name, Object obj) {
+ Unsafe unsafe = Unsafe.getUnsafe();
+ Class<?> k = ClassLoader.class;
+ long offset;
+ offset = unsafe.objectFieldOffset(k, name);
+ return unsafe.compareAndSetObject(this, offset, null, obj);
+ }
+}
+
+/*
+ * A utility class that will enumerate over an array of enumerations.
+ */
+final class CompoundEnumeration<E> implements Enumeration<E> {
+ private final Enumeration<E>[] enums;
+ private int index;
+
+ public CompoundEnumeration(Enumeration<E>[] enums) {
+ this.enums = enums;
+ }
+
+ private boolean next() {
+ while (index < enums.length) {
+ if (enums[index] != null && enums[index].hasMoreElements()) {
+ return true;
+ }
+ index++;
+ }
+ return false;
+ }
+
+ public boolean hasMoreElements() {
+ return next();
+ }
+
+ public E nextElement() {
+ if (!next()) {
+ throw new NoSuchElementException();
+ }
+ return enums[index].nextElement();
+ }
+}