--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/javax/imageio/spi/ServiceRegistry.java Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,835 @@
+/*
+ * Copyright 2000-2007 Sun Microsystems, Inc. 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. Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package javax.imageio.spi;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Set;
+import java.util.ServiceLoader;
+
+/**
+ * A registry for service provider instances.
+ *
+ * <p> 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 interface or subclass the class defined by the
+ * service itself.
+ *
+ * <p> Service providers are stored in one or more <i>categories</i>,
+ * each of which is defined by a class of interface (described by a
+ * <code>Class</code> object) that all of its members must implement.
+ * The set of categories may be changed dynamically.
+ *
+ * <p> Only a single instance of a given leaf class (that is, the
+ * actual class returned by <code>getClass()</code>, as opposed to any
+ * inherited classes or interfaces) may be registered. That is,
+ * suppose that the
+ * <code>com.mycompany.mypkg.GreenServiceProvider</code> class
+ * implements the <code>com.mycompany.mypkg.MyService</code>
+ * interface. If a <code>GreenServiceProvider</code> instance is
+ * registered, it will be stored in the category defined by the
+ * <code>MyService</code> class. If a new instance of
+ * <code>GreenServiceProvider</code> is registered, it will replace
+ * the previous instance. In practice, service provider objects are
+ * usually singletons so this behavior is appropriate.
+ *
+ * <p> To declare a service provider, a <code>services</code>
+ * subdirectory is placed within the <code>META-INF</code> directory
+ * that is present in every JAR file. This directory contains a file
+ * for each service provider interface that has one or more
+ * implementation classes present in the JAR file. For example, if
+ * the JAR file contained a class named
+ * <code>com.mycompany.mypkg.MyServiceImpl</code> which implements the
+ * <code>javax.someapi.SomeService</code> interface, the JAR file
+ * would contain a file named: <pre>
+ * META-INF/services/javax.someapi.SomeService </pre>
+ *
+ * containing the line:
+ *
+ * <pre>
+ * com.mycompany.mypkg.MyService
+ * </pre>
+ *
+ * <p> The service provider classes should be to be lightweight and
+ * quick to load. Implementations of these interfaces should avoid
+ * complex dependencies on other classes and on native code. The usual
+ * pattern for more complex services is to register a lightweight
+ * proxy for the heavyweight service.
+ *
+ * <p> An application may customize the contents of a registry as it
+ * sees fit, so long as it has the appropriate runtime permission.
+ *
+ * <p> For more details on declaring service providers, and the JAR
+ * format in general, see the <a
+ * href="../../../../technotes/guides/jar/jar.html">
+ * JAR File Specification</a>.
+ *
+ * @see RegisterableService
+ *
+ */
+public class ServiceRegistry {
+
+ // Class -> Registry
+ private Map categoryMap = new HashMap();
+
+ /**
+ * Constructs a <code>ServiceRegistry</code> instance with a
+ * set of categories taken from the <code>categories</code>
+ * argument.
+ *
+ * @param categories an <code>Iterator</code> containing
+ * <code>Class</code> objects to be used to define categories.
+ *
+ * @exception IllegalArgumentException if
+ * <code>categories</code> is <code>null</code>.
+ */
+ public ServiceRegistry(Iterator<Class<?>> categories) {
+ if (categories == null) {
+ throw new IllegalArgumentException("categories == null!");
+ }
+ while (categories.hasNext()) {
+ Class category = (Class)categories.next();
+ SubRegistry reg = new SubRegistry(this, category);
+ categoryMap.put(category, reg);
+ }
+ }
+
+ // The following two methods expose functionality from
+ // sun.misc.Service. If that class is made public, they may be
+ // removed.
+ //
+ // The sun.misc.ServiceConfigurationError class may also be
+ // exposed, in which case the references to 'an
+ // <code>Error</code>' below should be changed to 'a
+ // <code>ServiceConfigurationError</code>'.
+
+ /**
+ * Searches for implementations of a particular service class
+ * using the given class loader.
+ *
+ * <p> This method transforms the name of the given service class
+ * into a provider-configuration filename as described in the
+ * class comment and then uses the <code>getResources</code>
+ * 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 look up 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.
+ *
+ * @param providerClass a <code>Class</code>object indicating the
+ * class or interface of the service providers being detected.
+ *
+ * @param loader the class loader to be used to load
+ * provider-configuration files and instantiate provider classes,
+ * or <code>null</code> if the system class loader (or, failing that
+ * the bootstrap class loader) is to be used.
+ *
+ * @return An <code>Iterator</code> that yields provider objects
+ * for the given service, in some arbitrary order. The iterator
+ * will throw an <code>Error</code> if a provider-configuration
+ * file violates the specified format or if a provider class
+ * cannot be found and instantiated.
+ *
+ * @exception IllegalArgumentException if
+ * <code>providerClass</code> is <code>null</code>.
+ */
+ public static <T> Iterator<T> lookupProviders(Class<T> providerClass,
+ ClassLoader loader)
+ {
+ if (providerClass == null) {
+ throw new IllegalArgumentException("providerClass == null!");
+ }
+ return ServiceLoader.load(providerClass, loader).iterator();
+ }
+
+ /**
+ * 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 providerClass a <code>Class</code>object indicating the
+ * class or interface of the service providers being detected.
+ *
+ * @return An <code>Iterator</code> that yields provider objects
+ * for the given service, in some arbitrary order. The iterator
+ * will throw an <code>Error</code> if a provider-configuration
+ * file violates the specified format or if a provider class
+ * cannot be found and instantiated.
+ *
+ * @exception IllegalArgumentException if
+ * <code>providerClass</code> is <code>null</code>.
+ */
+ public static <T> Iterator<T> lookupProviders(Class<T> providerClass) {
+ if (providerClass == null) {
+ throw new IllegalArgumentException("providerClass == null!");
+ }
+ return ServiceLoader.load(providerClass).iterator();
+ }
+
+ /**
+ * Returns an <code>Iterator</code> of <code>Class</code> objects
+ * indicating the current set of categories. The iterator will be
+ * empty if no categories exist.
+ *
+ * @return an <code>Iterator</code> containing
+ * <code>Class</code>objects.
+ */
+ public Iterator<Class<?>> getCategories() {
+ Set keySet = categoryMap.keySet();
+ return keySet.iterator();
+ }
+
+ /**
+ * Returns an Iterator containing the subregistries to which the
+ * provider belongs.
+ */
+ private Iterator getSubRegistries(Object provider) {
+ List l = new ArrayList();
+ Iterator iter = categoryMap.keySet().iterator();
+ while (iter.hasNext()) {
+ Class c = (Class)iter.next();
+ if (c.isAssignableFrom(provider.getClass())) {
+ l.add((SubRegistry)categoryMap.get(c));
+ }
+ }
+ return l.iterator();
+ }
+
+ /**
+ * Adds a service provider object to the registry. The provider
+ * is associated with the given category.
+ *
+ * <p> If <code>provider</code> implements the
+ * <code>RegisterableService</code> interface, its
+ * <code>onRegistration</code> method will be called. Its
+ * <code>onDeregistration</code> method will be called each time
+ * it is deregistered from a category, for example if a
+ * category is removed or the registry is garbage collected.
+ *
+ * @param provider the service provide object to be registered.
+ * @param category the category under which to register the
+ * provider.
+ *
+ * @return true if no provider of the same class was previously
+ * registered in the same category category.
+ *
+ * @exception IllegalArgumentException if <code>provider</code> is
+ * <code>null</code>.
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ * @exception ClassCastException if provider does not implement
+ * the <code>Class</code> defined by <code>category</code>.
+ */
+ public <T> boolean registerServiceProvider(T provider,
+ Class<T> category) {
+ if (provider == null) {
+ throw new IllegalArgumentException("provider == null!");
+ }
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ if (!category.isAssignableFrom(provider.getClass())) {
+ throw new ClassCastException();
+ }
+
+ return reg.registerServiceProvider(provider);
+ }
+
+ /**
+ * Adds a service provider object to the registry. The provider
+ * is associated within each category present in the registry
+ * whose <code>Class</code> it implements.
+ *
+ * <p> If <code>provider</code> implements the
+ * <code>RegisterableService</code> interface, its
+ * <code>onRegistration</code> method will be called once for each
+ * category it is registered under. Its
+ * <code>onDeregistration</code> method will be called each time
+ * it is deregistered from a category or when the registry is
+ * finalized.
+ *
+ * @param provider the service provider object to be registered.
+ *
+ * @exception IllegalArgumentException if
+ * <code>provider</code> is <code>null</code>.
+ */
+ public void registerServiceProvider(Object provider) {
+ if (provider == null) {
+ throw new IllegalArgumentException("provider == null!");
+ }
+ Iterator regs = getSubRegistries(provider);
+ while (regs.hasNext()) {
+ SubRegistry reg = (SubRegistry)regs.next();
+ reg.registerServiceProvider(provider);
+ }
+ }
+
+ /**
+ * Adds a set of service provider objects, taken from an
+ * <code>Iterator</code> to the registry. Each provider is
+ * associated within each category present in the registry whose
+ * <code>Class</code> it implements.
+ *
+ * <p> For each entry of <code>providers</code> that implements
+ * the <code>RegisterableService</code> interface, its
+ * <code>onRegistration</code> method will be called once for each
+ * category it is registered under. Its
+ * <code>onDeregistration</code> method will be called each time
+ * it is deregistered from a category or when the registry is
+ * finalized.
+ *
+ * @param providers an Iterator containing service provider
+ * objects to be registered.
+ *
+ * @exception IllegalArgumentException if <code>providers</code>
+ * is <code>null</code> or contains a <code>null</code> entry.
+ */
+ public void registerServiceProviders(Iterator<?> providers) {
+ if (providers == null) {
+ throw new IllegalArgumentException("provider == null!");
+ }
+ while (providers.hasNext()) {
+ registerServiceProvider(providers.next());
+ }
+ }
+
+ /**
+ * Removes a service provider object from the given category. If
+ * the provider was not previously registered, nothing happens and
+ * <code>false</code> is returned. Otherwise, <code>true</code>
+ * is returned. If an object of the same class as
+ * <code>provider</code> but not equal (using <code>==</code>) to
+ * <code>provider</code> is registered, it will not be
+ * deregistered.
+ *
+ * <p> If <code>provider</code> implements the
+ * <code>RegisterableService</code> interface, its
+ * <code>onDeregistration</code> method will be called.
+ *
+ * @param provider the service provider object to be deregistered.
+ * @param category the category from which to deregister the
+ * provider.
+ *
+ * @return <code>true</code> if the provider was previously
+ * registered in the same category category,
+ * <code>false</code> otherwise.
+ *
+ * @exception IllegalArgumentException if <code>provider</code> is
+ * <code>null</code>.
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ * @exception ClassCastException if provider does not implement
+ * the class defined by <code>category</code>.
+ */
+ public <T> boolean deregisterServiceProvider(T provider,
+ Class<T> category) {
+ if (provider == null) {
+ throw new IllegalArgumentException("provider == null!");
+ }
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ if (!category.isAssignableFrom(provider.getClass())) {
+ throw new ClassCastException();
+ }
+ return reg.deregisterServiceProvider(provider);
+ }
+
+ /**
+ * Removes a service provider object from all categories that
+ * contain it.
+ *
+ * @param provider the service provider object to be deregistered.
+ *
+ * @exception IllegalArgumentException if <code>provider</code> is
+ * <code>null</code>.
+ */
+ public void deregisterServiceProvider(Object provider) {
+ if (provider == null) {
+ throw new IllegalArgumentException("provider == null!");
+ }
+ Iterator regs = getSubRegistries(provider);
+ while (regs.hasNext()) {
+ SubRegistry reg = (SubRegistry)regs.next();
+ reg.deregisterServiceProvider(provider);
+ }
+ }
+
+ /**
+ * Returns <code>true</code> if <code>provider</code> is currently
+ * registered.
+ *
+ * @param provider the service provider object to be queried.
+ *
+ * @return <code>true</code> if the given provider has been
+ * registered.
+ *
+ * @exception IllegalArgumentException if <code>provider</code> is
+ * <code>null</code>.
+ */
+ public boolean contains(Object provider) {
+ if (provider == null) {
+ throw new IllegalArgumentException("provider == null!");
+ }
+ Iterator regs = getSubRegistries(provider);
+ while (regs.hasNext()) {
+ SubRegistry reg = (SubRegistry)regs.next();
+ if (reg.contains(provider)) {
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ /**
+ * Returns an <code>Iterator</code> containing all registered
+ * service providers in the given category. If
+ * <code>useOrdering</code> is <code>false</code>, the iterator
+ * will return all of the server provider objects in an arbitrary
+ * order. Otherwise, the ordering will respect any pairwise
+ * orderings that have been set. If the graph of pairwise
+ * orderings contains cycles, any providers that belong to a cycle
+ * will not be returned.
+ *
+ * @param category the category to be retrieved from.
+ * @param useOrdering <code>true</code> if pairwise orderings
+ * should be taken account in ordering the returned objects.
+ *
+ * @return an <code>Iterator</code> containing service provider
+ * objects from the given category, possibly in order.
+ *
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ */
+ public <T> Iterator<T> getServiceProviders(Class<T> category,
+ boolean useOrdering) {
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ return reg.getServiceProviders(useOrdering);
+ }
+
+ /**
+ * A simple filter interface used by
+ * <code>ServiceRegistry.getServiceProviders</code> to select
+ * providers matching an arbitrary criterion. Classes that
+ * implement this interface should be defined in order to make use
+ * of the <code>getServiceProviders</code> method of
+ * <code>ServiceRegistry</code> that takes a <code>Filter</code>.
+ *
+ * @see ServiceRegistry#getServiceProviders(Class, ServiceRegistry.Filter, boolean)
+ */
+ public interface Filter {
+
+ /**
+ * Returns <code>true</code> if the given
+ * <code>provider</code> object matches the criterion defined
+ * by this <code>Filter</code>.
+ *
+ * @param provider a service provider <code>Object</code>.
+ *
+ * @return true if the provider matches the criterion.
+ */
+ boolean filter(Object provider);
+ }
+
+ /**
+ * Returns an <code>Iterator</code> containing service provider
+ * objects within a given category that satisfy a criterion
+ * imposed by the supplied <code>ServiceRegistry.Filter</code>
+ * object's <code>filter</code> method.
+ *
+ * <p> The <code>useOrdering</code> argument controls the
+ * ordering of the results using the same rules as
+ * <code>getServiceProviders(Class, boolean)</code>.
+ *
+ * @param category the category to be retrieved from.
+ * @param filter an instance of <code>ServiceRegistry.Filter</code>
+ * whose <code>filter</code> method will be invoked.
+ * @param useOrdering <code>true</code> if pairwise orderings
+ * should be taken account in ordering the returned objects.
+ *
+ * @return an <code>Iterator</code> containing service provider
+ * objects from the given category, possibly in order.
+ *
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ */
+ public <T> Iterator<T> getServiceProviders(Class<T> category,
+ Filter filter,
+ boolean useOrdering) {
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ Iterator iter = getServiceProviders(category, useOrdering);
+ return new FilterIterator(iter, filter);
+ }
+
+ /**
+ * Returns the currently registered service provider object that
+ * is of the given class type. At most one object of a given
+ * class is allowed to be registered at any given time. If no
+ * registered object has the desired class type, <code>null</code>
+ * is returned.
+ *
+ * @param providerClass the <code>Class</code> of the desired
+ * service provider object.
+ *
+ * @return a currently registered service provider object with the
+ * desired <code>Class</code>type, or <code>null</code> is none is
+ * present.
+ *
+ * @exception IllegalArgumentException if <code>providerClass</code> is
+ * <code>null</code>.
+ */
+ public <T> T getServiceProviderByClass(Class<T> providerClass) {
+ if (providerClass == null) {
+ throw new IllegalArgumentException("providerClass == null!");
+ }
+ Iterator iter = categoryMap.keySet().iterator();
+ while (iter.hasNext()) {
+ Class c = (Class)iter.next();
+ if (c.isAssignableFrom(providerClass)) {
+ SubRegistry reg = (SubRegistry)categoryMap.get(c);
+ T provider = reg.getServiceProviderByClass(providerClass);
+ if (provider != null) {
+ return provider;
+ }
+ }
+ }
+ return null;
+ }
+
+ /**
+ * Sets a pairwise ordering between two service provider objects
+ * within a given category. If one or both objects are not
+ * currently registered within the given category, or if the
+ * desired ordering is already set, nothing happens and
+ * <code>false</code> is returned. If the providers previously
+ * were ordered in the reverse direction, that ordering is
+ * removed.
+ *
+ * <p> The ordering will be used by the
+ * <code>getServiceProviders</code> methods when their
+ * <code>useOrdering</code> argument is <code>true</code>.
+ *
+ * @param category a <code>Class</code> object indicating the
+ * category under which the preference is to be established.
+ * @param firstProvider the preferred provider.
+ * @param secondProvider the provider to which
+ * <code>firstProvider</code> is preferred.
+ *
+ * @return <code>true</code> if a previously unset ordering
+ * was established.
+ *
+ * @exception IllegalArgumentException if either provider is
+ * <code>null</code> or they are the same object.
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ */
+ public <T> boolean setOrdering(Class<T> category,
+ T firstProvider,
+ T secondProvider) {
+ if (firstProvider == null || secondProvider == null) {
+ throw new IllegalArgumentException("provider is null!");
+ }
+ if (firstProvider == secondProvider) {
+ throw new IllegalArgumentException("providers are the same!");
+ }
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ if (reg.contains(firstProvider) &&
+ reg.contains(secondProvider)) {
+ return reg.setOrdering(firstProvider, secondProvider);
+ }
+ return false;
+ }
+
+ /**
+ * Sets a pairwise ordering between two service provider objects
+ * within a given category. If one or both objects are not
+ * currently registered within the given category, or if no
+ * ordering is currently set between them, nothing happens
+ * and <code>false</code> is returned.
+ *
+ * <p> The ordering will be used by the
+ * <code>getServiceProviders</code> methods when their
+ * <code>useOrdering</code> argument is <code>true</code>.
+ *
+ * @param category a <code>Class</code> object indicating the
+ * category under which the preference is to be disestablished.
+ * @param firstProvider the formerly preferred provider.
+ * @param secondProvider the provider to which
+ * <code>firstProvider</code> was formerly preferred.
+ *
+ * @return <code>true</code> if a previously set ordering was
+ * disestablished.
+ *
+ * @exception IllegalArgumentException if either provider is
+ * <code>null</code> or they are the same object.
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ */
+ public <T> boolean unsetOrdering(Class<T> category,
+ T firstProvider,
+ T secondProvider) {
+ if (firstProvider == null || secondProvider == null) {
+ throw new IllegalArgumentException("provider is null!");
+ }
+ if (firstProvider == secondProvider) {
+ throw new IllegalArgumentException("providers are the same!");
+ }
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ if (reg.contains(firstProvider) &&
+ reg.contains(secondProvider)) {
+ return reg.unsetOrdering(firstProvider, secondProvider);
+ }
+ return false;
+ }
+
+ /**
+ * Deregisters all service provider object currently registered
+ * under the given category.
+ *
+ * @param category the category to be emptied.
+ *
+ * @exception IllegalArgumentException if there is no category
+ * corresponding to <code>category</code>.
+ */
+ public void deregisterAll(Class<?> category) {
+ SubRegistry reg = (SubRegistry)categoryMap.get(category);
+ if (reg == null) {
+ throw new IllegalArgumentException("category unknown!");
+ }
+ reg.clear();
+ }
+
+ /**
+ * Deregisters all currently registered service providers from all
+ * categories.
+ */
+ public void deregisterAll() {
+ Iterator iter = categoryMap.values().iterator();
+ while (iter.hasNext()) {
+ SubRegistry reg = (SubRegistry)iter.next();
+ reg.clear();
+ }
+ }
+
+ /**
+ * Finalizes this object prior to garbage collection. The
+ * <code>deregisterAll</code> method is called to deregister all
+ * currently registered service providers. This method should not
+ * be called from application code.
+ *
+ * @exception Throwable if an error occurs during superclass
+ * finalization.
+ */
+ public void finalize() throws Throwable {
+ deregisterAll();
+ super.finalize();
+ }
+}
+
+
+/**
+ * A portion of a registry dealing with a single superclass or
+ * interface.
+ */
+class SubRegistry {
+
+ ServiceRegistry registry;
+
+ Class category;
+
+ // Provider Objects organized by partial oridering
+ PartiallyOrderedSet poset = new PartiallyOrderedSet();
+
+ // Class -> Provider Object of that class
+ Map<Class<?>,Object> map = new HashMap();
+
+ public SubRegistry(ServiceRegistry registry, Class category) {
+ this.registry = registry;
+ this.category = category;
+ }
+
+ public boolean registerServiceProvider(Object provider) {
+ Object oprovider = map.get(provider.getClass());
+ boolean present = oprovider != null;
+
+ if (present) {
+ deregisterServiceProvider(oprovider);
+ }
+ map.put(provider.getClass(), provider);
+ poset.add(provider);
+ if (provider instanceof RegisterableService) {
+ RegisterableService rs = (RegisterableService)provider;
+ rs.onRegistration(registry, category);
+ }
+
+ return !present;
+ }
+
+ /**
+ * If the provider was not previously registered, do nothing.
+ *
+ * @return true if the provider was previously registered.
+ */
+ public boolean deregisterServiceProvider(Object provider) {
+ Object oprovider = map.get(provider.getClass());
+
+ if (provider == oprovider) {
+ map.remove(provider.getClass());
+ poset.remove(provider);
+ if (provider instanceof RegisterableService) {
+ RegisterableService rs = (RegisterableService)provider;
+ rs.onDeregistration(registry, category);
+ }
+
+ return true;
+ }
+ return false;
+ }
+
+ public boolean contains(Object provider) {
+ Object oprovider = map.get(provider.getClass());
+ return oprovider == provider;
+ }
+
+ public boolean setOrdering(Object firstProvider,
+ Object secondProvider) {
+ return poset.setOrdering(firstProvider, secondProvider);
+ }
+
+ public boolean unsetOrdering(Object firstProvider,
+ Object secondProvider) {
+ return poset.unsetOrdering(firstProvider, secondProvider);
+ }
+
+ public Iterator getServiceProviders(boolean useOrdering) {
+ if (useOrdering) {
+ return poset.iterator();
+ } else {
+ return map.values().iterator();
+ }
+ }
+
+ public <T> T getServiceProviderByClass(Class<T> providerClass) {
+ return (T)map.get(providerClass);
+ }
+
+ public void clear() {
+ Iterator iter = map.values().iterator();
+ while (iter.hasNext()) {
+ Object provider = iter.next();
+ iter.remove();
+
+ if (provider instanceof RegisterableService) {
+ RegisterableService rs = (RegisterableService)provider;
+ rs.onDeregistration(registry, category);
+ }
+ }
+ poset.clear();
+ }
+
+ public void finalize() {
+ clear();
+ }
+}
+
+
+/**
+ * A class for wrapping <code>Iterators</code> with a filter function.
+ * This provides an iterator for a subset without duplication.
+ */
+class FilterIterator<T> implements Iterator<T> {
+
+ private Iterator<T> iter;
+ private ServiceRegistry.Filter filter;
+
+ private T next = null;
+
+ public FilterIterator(Iterator<T> iter,
+ ServiceRegistry.Filter filter) {
+ this.iter = iter;
+ this.filter = filter;
+ advance();
+ }
+
+ private void advance() {
+ while (iter.hasNext()) {
+ T elt = iter.next();
+ if (filter.filter(elt)) {
+ next = elt;
+ return;
+ }
+ }
+
+ next = null;
+ }
+
+ public boolean hasNext() {
+ return next != null;
+ }
+
+ public T next() {
+ if (next == null) {
+ throw new NoSuchElementException();
+ }
+ T o = next;
+ advance();
+ return o;
+ }
+
+ public void remove() {
+ throw new UnsupportedOperationException();
+ }
+}