Mercurial > jdk8-mips64-public > jaxws / file revision

 /*

  * Copyright (c) 1997, 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 com.sun.xml.internal.ws.util;

 import com.sun.istack.internal.NotNull;

 import com.sun.istack.internal.Nullable;

 import com.sun.xml.internal.ws.api.Component;

 import com.sun.xml.internal.ws.api.ComponentEx;

 import com.sun.xml.internal.ws.api.server.ContainerResolver;

 import java.io.BufferedReader;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.lang.reflect.Array;

 import java.net.URL;

 import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.Collection;

 import java.util.Collections;

 import java.util.Enumeration;

 import java.util.Iterator;

 import java.util.List;

 import java.util.NoSuchElementException;

 import java.util.Set;

 import java.util.TreeSet;

 import java.util.WeakHashMap;

 import java.util.concurrent.ConcurrentHashMap;

 /**

  * 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/>

  * <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/>

  * <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/>

  * <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/>

  * <p> <b>Example:</b> Suppose we have a service class named

  * <tt>java.io.spi.CharCodec</tt>.  It has two abstract methods:

  * <p/>

  * <pre>

  *   public abstract CharEncoder getEncoder(String encodingName);

  *   public abstract CharDecoder getDecoder(String encodingName);

  * </pre>

  * <p/>

  * 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/>

  * <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:

  * <p/>

  * <pre>

  *   sun.io.StandardCodec    # Standard codecs for the platform

  * </pre>

  * <p/>

  * To locate an codec for a given encoding name, the internal I/O code would

  * do something like this:

  * <p/>

  * <pre>

  *   CharEncoder getEncoder(String encodingName) {

  *       for( CharCodec cc : ServiceFinder.find(CharCodec.class) ) {

  *           CharEncoder ce = cc.getEncoder(encodingName);

  *           if (ce != null)

  *               return ce;

  *       }

  *       return null;

  *   }

  * </pre>

  * <p/>

  * 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

  * @version 1.11, 03/12/19

  * @since 1.3

  */

 public final class ServiceFinder<T> implements Iterable<T> {

     private static final String prefix = "META-INF/services/";

     private static WeakHashMap<ClassLoader, ConcurrentHashMap<String, ServiceName[]>> serviceNameCache

              = new WeakHashMap<ClassLoader, ConcurrentHashMap<String, ServiceName[]>>();

     private final Class<T> serviceClass;

     private final @Nullable ClassLoader classLoader;

     private final @Nullable ComponentEx component;

     private static class ServiceName {

         final String className;

         final URL config;

         public ServiceName(String className, URL config) {

             this.className = className;

             this.config = config;

         }

     }

     public static <T> ServiceFinder<T> find(@NotNull Class<T> service, @Nullable ClassLoader loader, Component component) {

         return new ServiceFinder<T>(service, loader, component);

     }

     public static <T> ServiceFinder<T> find(@NotNull Class<T> service, Component component) {

         return find(service,Thread.currentThread().getContextClassLoader(),component);

     }

     /**

      * Locates and incrementally instantiates the available providers of a

      * given service using the given class loader.

      * <p/>

      * <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/>

      * <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

      * @throws ServiceConfigurationError If a provider-configuration file violates the specified format

      *                                   or names a provider class that cannot be found and instantiated

      * @see #find(Class)

      */

     public static <T> ServiceFinder<T> find(@NotNull Class<T> service, @Nullable ClassLoader loader) {

         return find(service, loader, ContainerResolver.getInstance().getContainer());

     }

     /**

      * Locates and incrementally instantiates the available providers of a

      * given service using the context class loader.  This convenience method

      * is equivalent to

      * <p/>

      * <pre>

      *   ClassLoader cl = Thread.currentThread().getContextClassLoader();

      *   return Service.providers(service, cl);

      * </pre>

      *

      * @param service The service's abstract service class

      *

      * @throws ServiceConfigurationError If a provider-configuration file violates the specified format

      *                                   or names a provider class that cannot be found and instantiated

      * @see #find(Class, ClassLoader)

      */

     public static <T> ServiceFinder<T> find(Class<T> service) {

         return find(service,Thread.currentThread().getContextClassLoader());

     }

     private ServiceFinder(Class<T> service, ClassLoader loader, Component component) {

         this.serviceClass = service;

         this.classLoader = loader;

         this.component = getComponentEx(component);

     }

     private static ServiceName[] serviceClassNames(Class serviceClass, ClassLoader classLoader) {

         ArrayList<ServiceName> l = new ArrayList<ServiceName>();

         for (Iterator<ServiceName> it = new ServiceNameIterator(serviceClass,classLoader);it.hasNext();) l.add(it.next());

         return l.toArray(new ServiceName[l.size()]);

     }

     /**

      * Returns discovered objects incrementally.

      *

      * @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.

      */

     @SuppressWarnings("unchecked")

         public Iterator<T> iterator() {

         Iterator<T> it = new LazyIterator<T>(serviceClass,classLoader);

         return component != null ?

                         new CompositeIterator<T>(

                                         component.getIterableSPI(serviceClass).iterator(),it) :

                         it;

     }

     /**

      * Returns discovered objects all at once.

      *

      * @return

      *      can be empty but never null.

      *

      * @throws ServiceConfigurationError

      */

     public T[] toArray() {

         List<T> result = new ArrayList<T>();

         for (T t : this) {

             result.add(t);

         }

         return result.toArray((T[])Array.newInstance(serviceClass,result.size()));

     }

     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 u        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

      */

     @SuppressWarnings({"StatementWithEmptyBody"})

     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<String>();

         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 static ComponentEx getComponentEx(Component component) {

         if (component instanceof ComponentEx)

                 return (ComponentEx) component;

         return component != null ? new ComponentExWrapper(component) : null;

     }

     private static class ComponentExWrapper implements ComponentEx {

         private final Component component;

         public ComponentExWrapper(Component component) {

                 this.component = component;

         }

                 public <S> S getSPI(Class<S> spiType) {

                         return component.getSPI(spiType);

                 }

                 public <S> Iterable<S> getIterableSPI(Class<S> spiType) {

                 S item = getSPI(spiType);

                 if (item != null) {

                         Collection<S> c = Collections.singletonList(item);

                         return c;

                 }

                 return Collections.emptySet();

                 }

     }

     private static class CompositeIterator<T> implements Iterator<T> {

         private final Iterator<Iterator<T>> it;

         private Iterator<T> current = null;

         public CompositeIterator(Iterator<T>... iterators) {

                 it = Arrays.asList(iterators).iterator();

         }

                 public boolean hasNext() {

                         if (current != null && current.hasNext())

                                 return true;

                         while (it.hasNext()) {

                                 current = it.next();

                                 if (current.hasNext())

                                         return true;

                         }

                         return false;

                 }

                 public T next() {

                         if (!hasNext())

                                 throw new NoSuchElementException();

                         return current.next();

                 }

                 public void remove() {

             throw new UnsupportedOperationException();

                 }

     }

     /**

      * Private inner class implementing fully-lazy provider lookup

      */

     private static class ServiceNameIterator implements Iterator<ServiceName> {

         Class service;

         @Nullable ClassLoader loader;

         Enumeration<URL> configs = null;

         Iterator<String> pending = null;

         Set<String> returned = new TreeSet<String>();

         String nextName = null;

         URL currentConfig = null;

         private ServiceNameIterator(Class 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;

                 }

                 currentConfig = configs.nextElement();

                 pending = parse(service, currentConfig, returned);

             }

             nextName = pending.next();

             return true;

         }

         public ServiceName next() throws ServiceConfigurationError {

             if (!hasNext()) {

                 throw new NoSuchElementException();

             }

             String cn = nextName;

             nextName = null;

             return new ServiceName(cn, currentConfig);

         }

         public void remove() {

             throw new UnsupportedOperationException();

         }

     }

     private static class LazyIterator<T> implements Iterator<T> {

         Class<T> service;

         @Nullable ClassLoader loader;

         ServiceName[] names;

         int index;

         private LazyIterator(Class<T> service, ClassLoader loader) {

             this.service = service;

             this.loader = loader;

             this.names = null;

             index = 0;

         }

         @Override

         public boolean hasNext() {

             if (names == null) {

                 ConcurrentHashMap<String, ServiceName[]> nameMap = null;

                 synchronized(serviceNameCache){ nameMap = serviceNameCache.get(loader); }

                 names = (nameMap != null)? nameMap.get(service.getName()) : null;

                 if (names == null) {

                     names = serviceClassNames(service, loader);

                     if (nameMap == null) nameMap = new ConcurrentHashMap<String, ServiceName[]>();

                     nameMap.put(service.getName(), names);

                     synchronized(serviceNameCache){ serviceNameCache.put(loader,nameMap); }

                 }

             }

             return (index < names.length);

         }

         @Override

         public T next() {

             if (!hasNext()) throw new NoSuchElementException();

             ServiceName sn = names[index++];

             String cn = sn.className;

             URL currentConfig = sn.config;

             try {

                 return service.cast(Class.forName(cn, true, loader).newInstance());

             } catch (ClassNotFoundException x) {

                 fail(service, "Provider " + cn + " is specified in "+currentConfig+" but not found");

             } catch (Exception x) {

               fail(service, "Provider " + cn + " is specified in "+currentConfig+"but could not be instantiated: " + x, x);

             }

             return null;    /* This cannot happen */

         }

         @Override

         public void remove() {

             throw new UnsupportedOperationException();

         }

     }

 }