--- a/jdk/src/share/classes/sun/misc/Service.java Wed Feb 12 19:20:43 2014 +0800
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,434 +0,0 @@
-/*
- * Copyright (c) 1999, 2012, 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 sun.misc;
-
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.net.URL;
-import java.util.ArrayList;
-import java.util.Enumeration;
-import java.util.Iterator;
-import java.util.List;
-import java.util.NoSuchElementException;
-import java.util.Set;
-import java.util.TreeSet;
-
-
-/**
- * A simple service-provider lookup mechanism. A <i>service</i> is a
- * well-known set of interfaces and (usually abstract) classes. A <i>service
- * provider</i> is a specific implementation of a service. The classes in a
- * provider typically implement the interfaces and subclass the classes defined
- * in the service itself. Service providers may be installed in an
- * implementation of the Java platform in the form of extensions, that is, jar
- * files placed into any of the usual extension directories. Providers may
- * also be made available by adding them to the applet or application class
- * path or by some other platform-specific means.
- *
- * <p> In this lookup mechanism a service is represented by an interface or an
- * abstract class. (A concrete class may be used, but this is not
- * recommended.) A provider of a given service contains one or more concrete
- * classes that extend this <i>service class</i> with data and code specific to
- * the provider. This <i>provider class</i> will typically not be the entire
- * provider itself but rather a proxy that contains enough information to
- * decide whether the provider is able to satisfy a particular request together
- * with code that can create the actual provider on demand. The details of
- * provider classes tend to be highly service-specific; no single class or
- * interface could possibly unify them, so no such class has been defined. The
- * only requirement enforced here is that provider classes must have a
- * zero-argument constructor so that they may be instantiated during lookup.
- *
- * <p> A service provider identifies itself by placing a provider-configuration
- * file in the resource directory <tt>META-INF/services</tt>. The file's name
- * should consist of the fully-qualified name of the abstract service class.
- * The file should contain a list of fully-qualified concrete provider-class
- * names, one per line. Space and tab characters surrounding each name, as
- * well as blank lines, are ignored. The comment character is <tt>'#'</tt>
- * (<tt>0x23</tt>); on each line all characters following the first comment
- * character are ignored. The file must be encoded in UTF-8.
- *
- * <p> If a particular concrete provider class is named in more than one
- * configuration file, or is named in the same configuration file more than
- * once, then the duplicates will be ignored. The configuration file naming a
- * particular provider need not be in the same jar file or other distribution
- * unit as the provider itself. The provider must be accessible from the same
- * class loader that was initially queried to locate the configuration file;
- * note that this is not necessarily the class loader that found the file.
- *
- * <p> <b>Example:</b> Suppose we have a service class named
- * <tt>java.io.spi.CharCodec</tt>. It has two abstract methods:
- *
- * <pre>
- * public abstract CharEncoder getEncoder(String encodingName);
- * public abstract CharDecoder getDecoder(String encodingName);
- * </pre>
- *
- * Each method returns an appropriate object or <tt>null</tt> if it cannot
- * translate the given encoding. Typical <tt>CharCodec</tt> providers will
- * support more than one encoding.
- *
- * <p> If <tt>sun.io.StandardCodec</tt> is a provider of the <tt>CharCodec</tt>
- * service then its jar file would contain the file
- * <tt>META-INF/services/java.io.spi.CharCodec</tt>. This file would contain
- * the single line:
- *
- * <pre>
- * sun.io.StandardCodec # Standard codecs for the platform
- * </pre>
- *
- * To locate an encoder for a given encoding name, the internal I/O code would
- * do something like this:
- *
- * <pre>
- * CharEncoder getEncoder(String encodingName) {
- * Iterator ps = Service.providers(CharCodec.class);
- * while (ps.hasNext()) {
- * CharCodec cc = (CharCodec)ps.next();
- * CharEncoder ce = cc.getEncoder(encodingName);
- * if (ce != null)
- * return ce;
- * }
- * return null;
- * }
- * </pre>
- *
- * The provider-lookup mechanism always executes in the security context of the
- * caller. Trusted system code should typically invoke the methods in this
- * class from within a privileged security context.
- *
- * @author Mark Reinhold
- * @since 1.3
- */
-
-public final class Service<S> {
-
- private static final String prefix = "META-INF/services/";
-
- private Service() { }
-
- private static void fail(Class<?> service, String msg, Throwable cause)
- throws ServiceConfigurationError
- {
- ServiceConfigurationError sce
- = new ServiceConfigurationError(service.getName() + ": " + msg);
- sce.initCause(cause);
- throw sce;
- }
-
- private static void fail(Class<?> service, String msg)
- throws ServiceConfigurationError
- {
- throw new ServiceConfigurationError(service.getName() + ": " + msg);
- }
-
- private static void fail(Class<?> service, URL u, int line, String msg)
- throws ServiceConfigurationError
- {
- fail(service, u + ":" + line + ": " + msg);
- }
-
- /**
- * Parse a single line from the given configuration file, adding the name
- * on the line to both the names list and the returned set iff the name is
- * not already a member of the returned set.
- */
- private static int parseLine(Class<?> service, URL u, BufferedReader r, int lc,
- List<String> names, Set<String> returned)
- throws IOException, ServiceConfigurationError
- {
- String ln = r.readLine();
- if (ln == null) {
- return -1;
- }
- int ci = ln.indexOf('#');
- if (ci >= 0) ln = ln.substring(0, ci);
- ln = ln.trim();
- int n = ln.length();
- if (n != 0) {
- if ((ln.indexOf(' ') >= 0) || (ln.indexOf('\t') >= 0))
- fail(service, u, lc, "Illegal configuration-file syntax");
- int cp = ln.codePointAt(0);
- if (!Character.isJavaIdentifierStart(cp))
- fail(service, u, lc, "Illegal provider-class name: " + ln);
- for (int i = Character.charCount(cp); i < n; i += Character.charCount(cp)) {
- cp = ln.codePointAt(i);
- if (!Character.isJavaIdentifierPart(cp) && (cp != '.'))
- fail(service, u, lc, "Illegal provider-class name: " + ln);
- }
- if (!returned.contains(ln)) {
- names.add(ln);
- returned.add(ln);
- }
- }
- return lc + 1;
- }
-
- /**
- * Parse the content of the given URL as a provider-configuration file.
- *
- * @param service
- * The service class for which providers are being sought;
- * used to construct error detail strings
- *
- * @param url
- * The URL naming the configuration file to be parsed
- *
- * @param returned
- * A Set containing the names of provider classes that have already
- * been returned. This set will be updated to contain the names
- * that will be yielded from the returned <tt>Iterator</tt>.
- *
- * @return A (possibly empty) <tt>Iterator</tt> that will yield the
- * provider-class names in the given configuration file that are
- * not yet members of the returned set
- *
- * @throws ServiceConfigurationError
- * If an I/O error occurs while reading from the given URL, or
- * if a configuration-file format error is detected
- */
- private static Iterator<String> parse(Class<?> service, URL u, Set<String> returned)
- throws ServiceConfigurationError
- {
- InputStream in = null;
- BufferedReader r = null;
- ArrayList<String> names = new ArrayList<>();
- try {
- in = u.openStream();
- r = new BufferedReader(new InputStreamReader(in, "utf-8"));
- int lc = 1;
- while ((lc = parseLine(service, u, r, lc, names, returned)) >= 0);
- } catch (IOException x) {
- fail(service, ": " + x);
- } finally {
- try {
- if (r != null) r.close();
- if (in != null) in.close();
- } catch (IOException y) {
- fail(service, ": " + y);
- }
- }
- return names.iterator();
- }
-
-
- /**
- * Private inner class implementing fully-lazy provider lookup
- */
- private static class LazyIterator<S> implements Iterator<S> {
-
- Class<S> service;
- ClassLoader loader;
- Enumeration<URL> configs = null;
- Iterator<String> pending = null;
- Set<String> returned = new TreeSet<>();
- String nextName = null;
-
- private LazyIterator(Class<S> service, ClassLoader loader) {
- this.service = service;
- this.loader = loader;
- }
-
- public boolean hasNext() throws ServiceConfigurationError {
- if (nextName != null) {
- return true;
- }
- if (configs == null) {
- try {
- String fullName = prefix + service.getName();
- if (loader == null)
- configs = ClassLoader.getSystemResources(fullName);
- else
- configs = loader.getResources(fullName);
- } catch (IOException x) {
- fail(service, ": " + x);
- }
- }
- while ((pending == null) || !pending.hasNext()) {
- if (!configs.hasMoreElements()) {
- return false;
- }
- pending = parse(service, configs.nextElement(), returned);
- }
- nextName = pending.next();
- return true;
- }
-
- public S next() throws ServiceConfigurationError {
- if (!hasNext()) {
- throw new NoSuchElementException();
- }
- String cn = nextName;
- nextName = null;
- Class<?> c = null;
- try {
- c = Class.forName(cn, false, loader);
- } catch (ClassNotFoundException x) {
- fail(service,
- "Provider " + cn + " not found");
- }
- if (!service.isAssignableFrom(c)) {
- fail(service,
- "Provider " + cn + " not a subtype");
- }
- try {
- return service.cast(c.newInstance());
- } catch (Throwable x) {
- fail(service,
- "Provider " + cn + " could not be instantiated: " + x,
- x);
- }
- return null; /* This cannot happen */
- }
-
- public void remove() {
- throw new UnsupportedOperationException();
- }
-
- }
-
-
- /**
- * Locates and incrementally instantiates the available providers of a
- * given service using the given class loader.
- *
- * <p> This method transforms the name of the given service class into a
- * provider-configuration filename as described above and then uses the
- * <tt>getResources</tt> method of the given class loader to find all
- * available files with that name. These files are then read and parsed to
- * produce a list of provider-class names. The iterator that is returned
- * uses the given class loader to lookup and then instantiate each element
- * of the list.
- *
- * <p> Because it is possible for extensions to be installed into a running
- * Java virtual machine, this method may return different results each time
- * it is invoked. <p>
- *
- * @param service
- * The service's abstract service class
- *
- * @param loader
- * The class loader to be used to load provider-configuration files
- * and instantiate provider classes, or <tt>null</tt> if the system
- * class loader (or, failing that the bootstrap class loader) is to
- * be used
- *
- * @return An <tt>Iterator</tt> that yields provider objects for the given
- * service, in some arbitrary order. The iterator will throw a
- * <tt>ServiceConfigurationError</tt> if a provider-configuration
- * file violates the specified format or if a provider class cannot
- * be found and instantiated.
- *
- * @throws ServiceConfigurationError
- * If a provider-configuration file violates the specified format
- * or names a provider class that cannot be found and instantiated
- *
- * @see #providers(java.lang.Class)
- * @see #installedProviders(java.lang.Class)
- */
- public static <S> Iterator<S> providers(Class<S> service, ClassLoader loader)
- throws ServiceConfigurationError
- {
- return new LazyIterator<S>(service, loader);
- }
-
-
- /**
- * Locates and incrementally instantiates the available providers of a
- * given service using the context class loader. This convenience method
- * is equivalent to
- *
- * <pre>
- * ClassLoader cl = Thread.currentThread().getContextClassLoader();
- * return Service.providers(service, cl);
- * </pre>
- *
- * @param service
- * The service's abstract service class
- *
- * @return An <tt>Iterator</tt> that yields provider objects for the given
- * service, in some arbitrary order. The iterator will throw a
- * <tt>ServiceConfigurationError</tt> if a provider-configuration
- * file violates the specified format or if a provider class cannot
- * be found and instantiated.
- *
- * @throws ServiceConfigurationError
- * If a provider-configuration file violates the specified format
- * or names a provider class that cannot be found and instantiated
- *
- * @see #providers(java.lang.Class, java.lang.ClassLoader)
- */
- public static <S> Iterator<S> providers(Class<S> service)
- throws ServiceConfigurationError
- {
- ClassLoader cl = Thread.currentThread().getContextClassLoader();
- return Service.providers(service, cl);
- }
-
-
- /**
- * Locates and incrementally instantiates the available providers of a
- * given service using the extension class loader. This convenience method
- * simply locates the extension class loader, call it
- * <tt>extClassLoader</tt>, and then does
- *
- * <pre>
- * return Service.providers(service, extClassLoader);
- * </pre>
- *
- * If the extension class loader cannot be found then the system class
- * loader is used; if there is no system class loader then the bootstrap
- * class loader is used.
- *
- * @param service
- * The service's abstract service class
- *
- * @return An <tt>Iterator</tt> that yields provider objects for the given
- * service, in some arbitrary order. The iterator will throw a
- * <tt>ServiceConfigurationError</tt> if a provider-configuration
- * file violates the specified format or if a provider class cannot
- * be found and instantiated.
- *
- * @throws ServiceConfigurationError
- * If a provider-configuration file violates the specified format
- * or names a provider class that cannot be found and instantiated
- *
- * @see #providers(java.lang.Class, java.lang.ClassLoader)
- */
- public static <S> Iterator<S> installedProviders(Class<S> service)
- throws ServiceConfigurationError
- {
- ClassLoader cl = ClassLoader.getSystemClassLoader();
- ClassLoader prev = null;
- while (cl != null) {
- prev = cl;
- cl = cl.getParent();
- }
- return Service.providers(service, prev);
- }
-
-}