--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.base/share/classes/java/lang/ClassLoader.java Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,2200 @@
+/*
+ * Copyright (c) 2013, 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.File;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.security.AccessController;
+import java.security.AccessControlContext;
+import java.security.CodeSource;
+import java.security.Policy;
+import java.security.PrivilegedAction;
+import java.security.PrivilegedActionException;
+import java.security.PrivilegedExceptionAction;
+import java.security.ProtectionDomain;
+import java.security.cert.Certificate;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.Stack;
+import java.util.Map;
+import java.util.Vector;
+import java.util.Hashtable;
+import java.util.WeakHashMap;
+import java.util.concurrent.ConcurrentHashMap;
+import sun.misc.CompoundEnumeration;
+import sun.misc.Resource;
+import sun.misc.URLClassPath;
+import sun.misc.VM;
+import sun.reflect.CallerSensitive;
+import sun.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 <tt>ClassLoader</tt> 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 Class <tt>Class</tt>} object contains a {@link
+ * Class#getClassLoader() reference} to the <tt>ClassLoader</tt> that defined
+ * it.
+ *
+ * <p> <tt>Class</tt> 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 <tt>ClassLoader</tt> 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> The <tt>ClassLoader</tt> class uses a delegation model to search for
+ * classes and resources. Each instance of <tt>ClassLoader</tt> has an
+ * associated parent class loader. When requested to find a class or
+ * resource, a <tt>ClassLoader</tt> instance will delegate the search for the
+ * class or resource to its parent class loader before attempting to find the
+ * class or resource itself. The virtual machine's built-in class loader,
+ * called the "bootstrap class loader", does not itself have a parent but may
+ * serve as the parent of a <tt>ClassLoader</tt> instance.
+ *
+ * <p> Class loaders that support concurrent loading of classes are known as
+ * <em>parallel capable</em> class loaders and are required to register
+ * themselves at their class initialization time by invoking the
+ * {@link
+ * #registerAsParallelCapable <tt>ClassLoader.registerAsParallelCapable</tt>}
+ * method. Note that the <tt>ClassLoader</tt> class is registered as parallel
+ * capable by default. However, its subclasses still need to register themselves
+ * if they are parallel capable. <br>
+ * 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
+ * <tt>loadClass</tt>} methods).
+ *
+ * <p> Normally, the Java virtual machine loads classes from the local file
+ * system in a platform-dependent manner. For example, on UNIX systems, the
+ * virtual machine loads classes from the directory defined by the
+ * <tt>CLASSPATH</tt> environment variable.
+ *
+ * <p> 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)
+ * <tt>defineClass</tt>} converts an array of bytes into an instance of class
+ * <tt>Class</tt>. Instances of this newly defined class can be created using
+ * {@link Class#newInstance <tt>Class.newInstance</tt>}.
+ *
+ * <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 <tt>loadClass</tt>} 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 <tt>findClass</tt>} and <tt>loadClassData</tt> 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 <tt>defineClass</tt>} 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 name="name">Binary names</a> </h3>
+ *
+ * <p> Any class name provided as a {@link String} parameter to methods in
+ * <tt>ClassLoader</tt> 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>
+ *
+ * {@code Class} objects for array classes are not created by {@code ClassLoader};
+ * use the {@link Class#forName} method instead.
+ *
+ * @jls 13.1 The Form of a Binary
+ * @see #resolveClass(Class)
+ * @since 1.0
+ */
+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;
+
+ /**
+ * 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 capabale.
+ * 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;
+
+ // Hashtable that 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);
+
+ // The initiating protection domains for all classes loaded by this loader
+ private final Set<ProtectionDomain> domains;
+
+ // 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 Package object.
+ // @GuardedBy("itself")
+ private final HashMap<String, Package> packages = new HashMap<>();
+
+ private static Void checkCreateClassLoader() {
+ SecurityManager security = System.getSecurityManager();
+ if (security != null) {
+ security.checkCreateClassLoader();
+ }
+ return null;
+ }
+
+ private ClassLoader(Void unused, ClassLoader parent) {
+ this.parent = parent;
+ if (ParallelLoaders.isRegistered(this.getClass())) {
+ parallelLockMap = new ConcurrentHashMap<>();
+ package2certs = new ConcurrentHashMap<>();
+ domains = Collections.synchronizedSet(new HashSet<>());
+ assertionLock = new Object();
+ } else {
+ // no finer-grained lock; lock on the classloader instance
+ parallelLockMap = null;
+ package2certs = new Hashtable<>();
+ domains = new HashSet<>();
+ assertionLock = this;
+ }
+ }
+
+ /**
+ * Creates a new class loader using the specified parent class loader for
+ * delegation.
+ *
+ * <p> If there is a security manager, its {@link
+ * SecurityManager#checkCreateClassLoader()
+ * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
+ * a security exception. </p>
+ *
+ * @param parent
+ * The parent class loader
+ *
+ * @throws SecurityException
+ * If a security manager exists and its
+ * <tt>checkCreateClassLoader</tt> method doesn't allow creation
+ * of a new class loader.
+ *
+ * @since 1.2
+ */
+ protected ClassLoader(ClassLoader parent) {
+ this(checkCreateClassLoader(), parent);
+ }
+
+ /**
+ * Creates a new class loader using the <tt>ClassLoader</tt> returned by
+ * the method {@link #getSystemClassLoader()
+ * <tt>getSystemClassLoader()</tt>} as the parent class loader.
+ *
+ * <p> If there is a security manager, its {@link
+ * SecurityManager#checkCreateClassLoader()
+ * <tt>checkCreateClassLoader</tt>} method is invoked. This may result in
+ * a security exception. </p>
+ *
+ * @throws SecurityException
+ * If a security manager exists and its
+ * <tt>checkCreateClassLoader</tt> method doesn't allow creation
+ * of a new class loader.
+ */
+ protected ClassLoader() {
+ this(checkCreateClassLoader(), getSystemClassLoader());
+ }
+
+ // -- 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) <tt>loadClass(name,
+ * false)</tt>}.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The resulting <tt>Class</tt> 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) <tt>loadClass</tt>} method
+ * on the parent class loader. If the parent is <tt>null</tt> the class
+ * loader built-in to 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
+ * <tt>resolve</tt> flag is true, this method will then invoke the {@link
+ * #resolveClass(Class)} method on the resulting <tt>Class</tt> object.
+ *
+ * <p> Subclasses of <tt>ClassLoader</tt> are encouraged to override {@link
+ * #findClass(String)}, rather than this method. </p>
+ *
+ * <p> Unless overridden, this method synchronizes on the result of
+ * {@link #getClassLoadingLock <tt>getClassLoadingLock</tt>} method
+ * during the entire class loading process.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @param resolve
+ * If <tt>true</tt> then resolve the class
+ *
+ * @return The resulting <tt>Class</tt> 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
+ sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
+ sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
+ sun.misc.PerfCounter.getFindClasses().increment();
+ }
+ }
+ if (resolve) {
+ resolveClass(c);
+ }
+ return c;
+ }
+ }
+
+ /**
+ * 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 <tt>className</tt> 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<Void>() {
+ public Void run() {
+ sm.checkPackageAccess(name.substring(0, i));
+ return null;
+ }
+ }, new AccessControlContext(new ProtectionDomain[] {pd}));
+ }
+ }
+ domains.add(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 <tt>loadClass</tt>} method after checking the
+ * parent class loader for the requested class. The default implementation
+ * throws a <tt>ClassNotFoundException</tt>.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The resulting <tt>Class</tt> object
+ *
+ * @throws ClassNotFoundException
+ * If the class could not be found
+ *
+ * @since 1.2
+ */
+ protected Class<?> findClass(String name) throws ClassNotFoundException {
+ throw new ClassNotFoundException(name);
+ }
+
+ /**
+ * Converts an array of bytes into an instance of class <tt>Class</tt>.
+ * Before the <tt>Class</tt> 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
+ * <tt>off</tt> through <tt>off+len-1</tt> 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 <tt>b</tt> of the class data
+ *
+ * @param len
+ * The length of the class data
+ *
+ * @return The <tt>Class</tt> object that was created from the specified
+ * class data
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class
+ *
+ * @throws IndexOutOfBoundsException
+ * If either <tt>off</tt> or <tt>len</tt> is negative, or if
+ * <tt>off+len</tt> is greater than <tt>b.length</tt>.
+ *
+ * @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
+ 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 <tt>Class</tt>.
+ * Before the <tt>Class</tt> can be used it must be resolved.
+ *
+ * <p> This method assigns a default {@link java.security.ProtectionDomain
+ * <tt>ProtectionDomain</tt>} to the newly defined class. The
+ * <tt>ProtectionDomain</tt> is effectively granted the same set of
+ * permissions returned when {@link
+ * java.security.Policy#getPermissions(java.security.CodeSource)
+ * <tt>Policy.getPolicy().getPermissions(new CodeSource(null, null))</tt>}
+ * is invoked. The default domain is created on the first invocation of
+ * {@link #defineClass(String, byte[], int, int) <tt>defineClass</tt>},
+ * and re-used on subsequent invocations.
+ *
+ * <p> To assign a specific <tt>ProtectionDomain</tt> to the class, use
+ * the {@link #defineClass(String, byte[], int, int,
+ * java.security.ProtectionDomain) <tt>defineClass</tt>} method that takes a
+ * <tt>ProtectionDomain</tt> as one of its arguments. </p>
+ *
+ * @param name
+ * The expected <a href="#name">binary name</a> of the class, or
+ * <tt>null</tt> if not known
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes in positions
+ * <tt>off</tt> through <tt>off+len-1</tt> 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 <tt>b</tt> of the class data
+ *
+ * @param len
+ * The length of the class data
+ *
+ * @return The <tt>Class</tt> object that was created from the specified
+ * class data.
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class
+ *
+ * @throws IndexOutOfBoundsException
+ * If either <tt>off</tt> or <tt>len</tt> is negative, or if
+ * <tt>off+len</tt> is greater than <tt>b.length</tt>.
+ *
+ * @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
+ * <tt>name</tt> begins with "<tt>java.</tt>".
+ *
+ * @see #loadClass(String, boolean)
+ * @see #resolveClass(Class)
+ * @see java.security.CodeSource
+ * @see java.security.SecureClassLoader
+ *
+ * @since 1.1
+ */
+ 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);
+
+ if ((name != null) && name.startsWith("java.")) {
+ 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)
+ {
+ 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 <tt>Class</tt>,
+ * with an optional <tt>ProtectionDomain</tt>. If the domain is
+ * <tt>null</tt>, then a default 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 <tt>CodeSource</tt>} within the
+ * <tt>ProtectionDomain</tt> of the class. Any classes added to that
+ * package must contain the same set of certificates or a
+ * <tt>SecurityException</tt> will be thrown. Note that if
+ * <tt>name</tt> is <tt>null</tt>, 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> The specified <tt>name</tt> cannot begin with "<tt>java.</tt>", since
+ * all classes in the "<tt>java.*</tt> packages can only be defined by the
+ * bootstrap class loader. If <tt>name</tt> is not <tt>null</tt>, it
+ * must be equal to the <a href="#name">binary name</a> of the class
+ * specified by the byte array "<tt>b</tt>", otherwise a {@link
+ * NoClassDefFoundError <tt>NoClassDefFoundError</tt>} will be thrown. </p>
+ *
+ * @param name
+ * The expected <a href="#name">binary name</a> of the class, or
+ * <tt>null</tt> if not known
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes in positions
+ * <tt>off</tt> through <tt>off+len-1</tt> 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 <tt>b</tt> of the class data
+ *
+ * @param len
+ * The length of the class data
+ *
+ * @param protectionDomain
+ * The ProtectionDomain of the class
+ *
+ * @return The <tt>Class</tt> object created from the data,
+ * and optional <tt>ProtectionDomain</tt>.
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class
+ *
+ * @throws NoClassDefFoundError
+ * If <tt>name</tt> is not equal to the <a href="#name">binary
+ * name</a> of the class specified by <tt>b</tt>
+ *
+ * @throws IndexOutOfBoundsException
+ * If either <tt>off</tt> or <tt>len</tt> is negative, or if
+ * <tt>off+len</tt> is greater than <tt>b.length</tt>.
+ *
+ * @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 <tt>name</tt> begins with
+ * "<tt>java.</tt>".
+ */
+ 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(name, b, off, len, protectionDomain, source);
+ postDefineClass(c, protectionDomain);
+ return c;
+ }
+
+ /**
+ * Converts a {@link java.nio.ByteBuffer <tt>ByteBuffer</tt>}
+ * into an instance of class <tt>Class</tt>,
+ * with an optional <tt>ProtectionDomain</tt>. If the domain is
+ * <tt>null</tt>, then a default 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, and the restrictions on class names
+ * 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><tt>.defineClass(</tt><i>name</i><tt>,</tt>
+ * <i>bBuffer</i><tt>,</tt> <i>pd</i><tt>)</tt> yields exactly the same
+ * result as the statements
+ *
+ *<p> <tt>
+ * ...<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>
+ * </tt></p>
+ *
+ * @param name
+ * The expected <a href="#name">binary name</a>. of the class, or
+ * <tt>null</tt> if not known
+ *
+ * @param b
+ * The bytes that make up the class data. The bytes from positions
+ * <tt>b.position()</tt> through <tt>b.position() + b.limit() -1
+ * </tt> should have the format of a valid class file as defined by
+ * <cite>The Java™ Virtual Machine Specification</cite>.
+ *
+ * @param protectionDomain
+ * The ProtectionDomain of the class, or <tt>null</tt>.
+ *
+ * @return The <tt>Class</tt> object created from the data,
+ * and optional <tt>ProtectionDomain</tt>.
+ *
+ * @throws ClassFormatError
+ * If the data did not contain a valid class.
+ *
+ * @throws NoClassDefFoundError
+ * If <tt>name</tt> is not equal to the <a href="#name">binary
+ * name</a> of the class specified by <tt>b</tt>
+ *
+ * @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 <tt>name</tt> begins with
+ * "<tt>java.</tt>".
+ *
+ * @see #defineClass(String, byte[], int, int, ProtectionDomain)
+ *
+ * @since 1.5
+ */
+ protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
+ ProtectionDomain protectionDomain)
+ throws ClassFormatError
+ {
+ int len = b.remaining();
+
+ // Use byte[] if not a direct ByteBufer:
+ 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(name, b, b.position(), len, protectionDomain, source);
+ postDefineClass(c, protectionDomain);
+ return c;
+ }
+
+ private native Class<?> defineClass1(String name, byte[] b, int off, int len,
+ ProtectionDomain pd, String source);
+
+ private native Class<?> defineClass2(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 <tt>c</tt> 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 <tt>c</tt> is <tt>null</tt>.
+ *
+ * @see #defineClass(String, byte[], int, int)
+ */
+ protected final void resolveClass(Class<?> c) {
+ resolveClass0(c);
+ }
+
+ private native void resolveClass0(Class<?> c);
+
+ /**
+ * 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 <tt>Class</tt> object returned
+ * might have more than one <tt>ClassLoader</tt> associated with it.
+ * Subclasses of <tt>ClassLoader</tt> 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 <tt>Class</tt> object for the specified <tt>name</tt>
+ *
+ * @throws ClassNotFoundException
+ * If the class could not be found
+ *
+ * @see #ClassLoader(ClassLoader)
+ * @see #getParent()
+ */
+ protected final Class<?> findSystemClass(String name)
+ throws ClassNotFoundException
+ {
+ ClassLoader system = getSystemClassLoader();
+ if (system == null) {
+ if (!checkName(name))
+ throw new ClassNotFoundException(name);
+ Class<?> cls = findBootstrapClass(name);
+ if (cls == null) {
+ throw new ClassNotFoundException(name);
+ }
+ return cls;
+ }
+ return system.loadClass(name);
+ }
+
+ /**
+ * Returns a class loaded by the bootstrap class loader;
+ * or return null if not found.
+ */
+ private 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
+ * <tt>null</tt> is returned.
+ *
+ * @param name
+ * The <a href="#name">binary name</a> of the class
+ *
+ * @return The <tt>Class</tt> object, or <tt>null</tt> 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 native final Class<?> findLoadedClass0(String name);
+
+ /**
+ * Sets the signers of a class. This should be invoked after defining a
+ * class.
+ *
+ * @param c
+ * The <tt>Class</tt> object
+ *
+ * @param signers
+ * The signers for the class
+ *
+ * @since 1.1
+ */
+ protected final void setSigners(Class<?> c, Object[] signers) {
+ c.setSigners(signers);
+ }
+
+
+ // -- Resource --
+
+ /**
+ * 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 '<tt>/</tt>'-separated path name that
+ * identifies the resource.
+ *
+ * <p> This method will first search the parent class loader for the
+ * resource; if the parent is <tt>null</tt> the path of the class loader
+ * built-in to the virtual machine is searched. That failing, this method
+ * will invoke {@link #findResource(String)} to find the resource. </p>
+ *
+ * @apiNote 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 A <tt>URL</tt> object for reading the resource, or
+ * <tt>null</tt> if the resource could not be found or the invoker
+ * doesn't have adequate privileges to get the resource.
+ *
+ * @since 1.1
+ */
+ public URL getResource(String name) {
+ URL url;
+ if (parent != null) {
+ url = parent.getResource(name);
+ } else {
+ url = getBootstrapResource(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 <tt>/</tt>-separated path name that
+ * identifies the resource.
+ *
+ * <p> The search order is described in the documentation for {@link
+ * #getResource(String)}. </p>
+ *
+ * @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 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 <tt>URL</tt>} objects for
+ * the resource. If no resources could be found, the enumeration
+ * will be empty. Resources that the class loader doesn't have
+ * access to will not be in the enumeration.
+ *
+ * @throws IOException
+ * If I/O errors occur
+ *
+ * @see #findResources(String)
+ *
+ * @since 1.2
+ */
+ public Enumeration<URL> getResources(String name) throws IOException {
+ @SuppressWarnings("unchecked")
+ Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2];
+ if (parent != null) {
+ tmp[0] = parent.getResources(name);
+ } else {
+ tmp[0] = getBootstrapResources(name);
+ }
+ tmp[1] = findResources(name);
+
+ return new CompoundEnumeration<>(tmp);
+ }
+
+ /**
+ * Finds the resource with the given name. Class loader implementations
+ * should override this method to specify where to find resources.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return A <tt>URL</tt> object for reading the resource, or
+ * <tt>null</tt> if the resource could not be found
+ *
+ * @since 1.2
+ */
+ protected URL findResource(String name) {
+ return null;
+ }
+
+ /**
+ * Returns an enumeration of {@link java.net.URL <tt>URL</tt>} objects
+ * representing all the resources with the given name. Class loader
+ * implementations should override this method to specify where to load
+ * resources from.
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An enumeration of {@link java.net.URL <tt>URL</tt>} objects for
+ * the resources
+ *
+ * @throws IOException
+ * If I/O errors occur
+ *
+ * @since 1.2
+ */
+ protected Enumeration<URL> findResources(String name) throws IOException {
+ return java.util.Collections.emptyEnumeration();
+ }
+
+ /**
+ * Registers the caller as 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 true if the caller is successfully registered as
+ * parallel capable and false if otherwise.
+ *
+ * @since 1.7
+ */
+ @CallerSensitive
+ protected static boolean registerAsParallelCapable() {
+ Class<? extends ClassLoader> callerClass =
+ Reflection.getCallerClass().asSubclass(ClassLoader.class);
+ return ParallelLoaders.register(callerClass);
+ }
+
+ /**
+ * 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()}).
+ *
+ * @param name
+ * The resource name
+ *
+ * @return A {@link java.net.URL <tt>URL</tt>} object for reading the
+ * resource, or <tt>null</tt> if the resource could not be found
+ *
+ * @since 1.1
+ */
+ public static URL getSystemResource(String name) {
+ ClassLoader system = getSystemClassLoader();
+ if (system == null) {
+ return getBootstrapResource(name);
+ }
+ return system.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 <tt>Enumeration</tt>} of {@link
+ * java.net.URL <tt>URL</tt>} objects.
+ *
+ * <p> The search order is described in the documentation for {@link
+ * #getSystemResource(String)}. </p>
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An enumeration of resource {@link java.net.URL <tt>URL</tt>}
+ * objects
+ *
+ * @throws IOException
+ * If I/O errors occur
+
+ * @since 1.2
+ */
+ public static Enumeration<URL> getSystemResources(String name)
+ throws IOException
+ {
+ ClassLoader system = getSystemClassLoader();
+ if (system == null) {
+ return getBootstrapResources(name);
+ }
+ return system.getResources(name);
+ }
+
+ /**
+ * Find resources from the VM's built-in classloader.
+ */
+ private static URL getBootstrapResource(String name) {
+ URLClassPath ucp = getBootstrapClassPath();
+ Resource res = ucp.getResource(name);
+ return res != null ? res.getURL() : null;
+ }
+
+ /**
+ * Find resources from the VM's built-in classloader.
+ */
+ private static Enumeration<URL> getBootstrapResources(String name)
+ throws IOException
+ {
+ final Enumeration<Resource> e =
+ getBootstrapClassPath().getResources(name);
+ return new Enumeration<URL> () {
+ public URL nextElement() {
+ return e.nextElement().getURL();
+ }
+ public boolean hasMoreElements() {
+ return e.hasMoreElements();
+ }
+ };
+ }
+
+ // Returns the URLClassPath that is used for finding system resources.
+ static URLClassPath getBootstrapClassPath() {
+ return sun.misc.Launcher.getBootstrapClassPath();
+ }
+
+
+ /**
+ * Returns an input stream for reading the specified resource.
+ *
+ * <p> The search order is described in the documentation for {@link
+ * #getResource(String)}. </p>
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An input stream for reading the resource, or <tt>null</tt>
+ * if the resource could not be found
+ *
+ * @since 1.1
+ */
+ public InputStream getResourceAsStream(String 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()}).
+ *
+ * @param name
+ * The resource name
+ *
+ * @return An input stream for reading the resource, or <tt>null</tt>
+ * if the resource could not be found
+ *
+ * @since 1.1
+ */
+ 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 <tt>null</tt> to represent the bootstrap class loader. This method
+ * will return <tt>null</tt> in such implementations if this class loader's
+ * parent is the bootstrap class loader.
+ *
+ * <p> If a security manager is present, and the invoker's class loader is
+ * not <tt>null</tt> and is not an ancestor of this class loader, then this
+ * method invokes the security manager's {@link
+ * SecurityManager#checkPermission(java.security.Permission)
+ * <tt>checkPermission</tt>} method with a {@link
+ * RuntimePermission#RuntimePermission(String)
+ * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
+ * access to the parent class loader is permitted. If not, a
+ * <tt>SecurityException</tt> will be thrown. </p>
+ *
+ * @return The parent <tt>ClassLoader</tt>
+ *
+ * @throws SecurityException
+ * If a security manager exists and its <tt>checkPermission</tt>
+ * method doesn't allow access to this class loader's parent class
+ * loader.
+ *
+ * @since 1.2
+ */
+ @CallerSensitive
+ public final ClassLoader getParent() {
+ if (parent == null)
+ return null;
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ checkClassLoaderPermission(this, Reflection.getCallerClass());
+ }
+ return parent;
+ }
+
+ /**
+ * Returns the system class loader for delegation. This is the default
+ * delegation parent for new <tt>ClassLoader</tt> 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 and sets it
+ * as the context class loader of the invoking <tt>Thread</tt>.
+ *
+ * <p> The default system class loader is an implementation-dependent
+ * instance of this class.
+ *
+ * <p> If the system property "<tt>java.system.class.loader</tt>" 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 <tt>ClassLoader</tt> 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.
+ *
+ * <p> If a security manager is present, and the invoker's class loader is
+ * not <tt>null</tt> and the invoker's class loader is not the same as or
+ * an ancestor of the system class loader, then this method invokes the
+ * security manager's {@link
+ * SecurityManager#checkPermission(java.security.Permission)
+ * <tt>checkPermission</tt>} method with a {@link
+ * RuntimePermission#RuntimePermission(String)
+ * <tt>RuntimePermission("getClassLoader")</tt>} permission to verify
+ * access to the system class loader. If not, a
+ * <tt>SecurityException</tt> will be thrown. </p>
+ *
+ * @return The system <tt>ClassLoader</tt> for delegation, or
+ * <tt>null</tt> if none
+ *
+ * @throws SecurityException
+ * If a security manager exists and its <tt>checkPermission</tt>
+ * method doesn't allow access to the system class loader.
+ *
+ * @throws IllegalStateException
+ * If invoked recursively during the construction of the class
+ * loader specified by the "<tt>java.system.class.loader</tt>"
+ * property.
+ *
+ * @throws Error
+ * If the system property "<tt>java.system.class.loader</tt>"
+ * 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
+ */
+ @CallerSensitive
+ public static ClassLoader getSystemClassLoader() {
+ initSystemClassLoader();
+ if (scl == null) {
+ return null;
+ }
+ SecurityManager sm = System.getSecurityManager();
+ if (sm != null) {
+ checkClassLoaderPermission(scl, Reflection.getCallerClass());
+ }
+ return scl;
+ }
+
+ private static synchronized void initSystemClassLoader() {
+ if (!sclSet) {
+ if (scl != null)
+ throw new IllegalStateException("recursive invocation");
+ sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
+ if (l != null) {
+ Throwable oops = null;
+ scl = l.getClassLoader();
+ try {
+ scl = AccessController.doPrivileged(
+ new SystemClassLoaderAction(scl));
+ } catch (PrivilegedActionException pae) {
+ oops = pae.getCause();
+ if (oops instanceof InvocationTargetException) {
+ oops = oops.getCause();
+ }
+ }
+ if (oops != null) {
+ if (oops instanceof Error) {
+ throw (Error) oops;
+ } else {
+ // wrap the exception
+ throw new Error(oops);
+ }
+ }
+ }
+ sclSet = true;
+ }
+ }
+
+ // 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();
+ }
+
+ 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 class loader for the system
+ // @GuardedBy("ClassLoader.class")
+ private static ClassLoader scl;
+
+ // Set to true once the system class loader has been set
+ // @GuardedBy("ClassLoader.class")
+ private static boolean sclSet;
+
+
+ // -- Package --
+
+ /**
+ * Defines a package by name in this <tt>ClassLoader</tt>. This allows
+ * class loaders to define the packages for their classes. Packages must
+ * be created before the class is defined, and package names must be
+ * unique within a class loader and cannot be redefined or changed once
+ * created.
+ *
+ * @param name
+ * The package name
+ *
+ * @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 <tt>null</tt>, then this package is sealed with
+ * respect to the given code source {@link java.net.URL
+ * <tt>URL</tt>} object. Otherwise, the package is not sealed.
+ *
+ * @return The newly defined <tt>Package</tt> object
+ *
+ * @throws IllegalArgumentException
+ * If package name duplicates an existing package either in this
+ * class loader or one of its ancestors
+ *
+ * @since 1.2
+ */
+ protected Package definePackage(String name, String specTitle,
+ String specVersion, String specVendor,
+ String implTitle, String implVersion,
+ String implVendor, URL sealBase)
+ throws IllegalArgumentException
+ {
+ synchronized (packages) {
+ Package pkg = getPackage(name);
+ if (pkg != null) {
+ throw new IllegalArgumentException(name);
+ }
+ pkg = new Package(name, specTitle, specVersion, specVendor,
+ implTitle, implVersion, implVendor,
+ sealBase, this);
+ packages.put(name, pkg);
+ return pkg;
+ }
+ }
+
+ /**
+ * Returns a <tt>Package</tt> that has been defined by this class loader
+ * or any of its ancestors.
+ *
+ * @param name
+ * The package name
+ *
+ * @return The <tt>Package</tt> corresponding to the given name, or
+ * <tt>null</tt> if not found
+ *
+ * @since 1.2
+ */
+ protected Package getPackage(String name) {
+ Package pkg;
+ synchronized (packages) {
+ pkg = packages.get(name);
+ }
+ if (pkg == null) {
+ if (parent != null) {
+ pkg = parent.getPackage(name);
+ } else {
+ pkg = Package.getSystemPackage(name);
+ }
+ if (pkg != null) {
+ synchronized (packages) {
+ Package pkg2 = packages.get(name);
+ if (pkg2 == null) {
+ packages.put(name, pkg);
+ } else {
+ pkg = pkg2;
+ }
+ }
+ }
+ }
+ return pkg;
+ }
+
+ /**
+ * Returns all of the <tt>Packages</tt> defined by this class loader and
+ * its ancestors.
+ *
+ * @return The array of <tt>Package</tt> objects defined by this
+ * <tt>ClassLoader</tt>
+ *
+ * @since 1.2
+ */
+ protected Package[] getPackages() {
+ Map<String, Package> map;
+ synchronized (packages) {
+ map = new HashMap<>(packages);
+ }
+ Package[] pkgs;
+ if (parent != null) {
+ pkgs = parent.getPackages();
+ } else {
+ pkgs = Package.getSystemPackages();
+ }
+ if (pkgs != null) {
+ for (Package pkg : pkgs) {
+ String pkgName = pkg.getName();
+ if (map.get(pkgName) == null) {
+ map.put(pkgName, pkg);
+ }
+ }
+ }
+ return map.values().toArray(new Package[map.size()]);
+ }
+
+
+ // -- 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 <tt>null</tt>, the VM
+ * searches the library along the path specified as the
+ * "<tt>java.library.path</tt>" 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 <tt>nativeLibraries</tt>. The native libraries loaded
+ * into the system are entered into the <tt>systemNativeLibraries</tt>
+ * vector.
+ *
+ * <p> Every native library requires a particular version of JNI. This is
+ * denoted by the private <tt>jniVersion</tt> 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);
+ static native String findBuiltinLib(String name);
+
+ public NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) {
+ this.name = name;
+ this.fromClass = fromClass;
+ this.isBuiltin = isBuiltin;
+ }
+
+ 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, "");
+ String ps = File.pathSeparator;
+ int ldlen = ldpath.length();
+ int i, j, n;
+ // Count the separators in the path
+ i = ldpath.indexOf(ps);
+ n = 0;
+ while (i >= 0) {
+ n++;
+ i = ldpath.indexOf(ps, i + 1);
+ }
+
+ // allocate the array of paths - n :'s = n + 1 path elements
+ String[] paths = new String[n + 1];
+
+ // Fill the array with paths from the ldpath
+ n = i = 0;
+ j = ldpath.indexOf(ps);
+ while (j >= 0) {
+ if (j - i > 0) {
+ paths[n++] = ldpath.substring(i, j);
+ } else if (j - i == 0) {
+ paths[n++] = ".";
+ }
+ i = j + 1;
+ j = ldpath.indexOf(ps, i);
+ }
+ paths[n] = ldpath.substring(i, 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");
+ }
+
+ private static boolean loadLibrary0(Class<?> fromClass, final File file) {
+ // Check to see if we're attempting to access a static library
+ String name = NativeLibrary.findBuiltinLib(file.getName());
+ boolean isBuiltin = (name != null);
+ if (!isBuiltin) {
+ name = AccessController.doPrivileged(
+ new PrivilegedAction<String>() {
+ 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
+ * <tt>true</tt> if classes loaded by this class loader will
+ * henceforth have assertions enabled by default, <tt>false</tt>
+ * 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 "<tt>p.</tt>". For example, <tt>javax.swing.text</tt> is a
+ * subpackage of <tt>javax.swing</tt>, and both <tt>java.util</tt> and
+ * <tt>java.lang.reflect</tt> are subpackages of <tt>java</tt>.
+ *
+ * <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 <tt>javax.lang</tt> and
+ * <tt>javax.lang.reflect</tt> both have package defaults associated with
+ * them, the latter package default applies to classes in
+ * <tt>javax.lang.reflect</tt>.
+ *
+ * <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 <tt>null</tt> value indicates the unnamed
+ * package that is "current"
+ * (see section 7.4.2 of
+ * <cite>The Java™ Language Specification</cite>.)
+ *
+ * @param enabled
+ * <tt>true</tt> if classes loaded by this classloader and
+ * belonging to the named package or any of its subpackages will
+ * have assertions enabled by default, <tt>false</tt> 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
+ * <tt>true</tt> if the named class is to have assertions
+ * enabled when (and if) it is initialized, <tt>false</tt> 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
+ * <tt>false</tt> 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();
+}
+
+
+class SystemClassLoaderAction
+ implements PrivilegedExceptionAction<ClassLoader> {
+ private ClassLoader parent;
+
+ SystemClassLoaderAction(ClassLoader parent) {
+ this.parent = parent;
+ }
+
+ public ClassLoader run() throws Exception {
+ String cls = System.getProperty("java.system.class.loader");
+ if (cls == null) {
+ return parent;
+ }
+
+ Constructor<?> ctor = Class.forName(cls, true, parent)
+ .getDeclaredConstructor(new Class<?>[] { ClassLoader.class });
+ ClassLoader sys = (ClassLoader) ctor.newInstance(
+ new Object[] { parent });
+ Thread.currentThread().setContextClassLoader(sys);
+ return sys;
+ }
+}