| /* |
| * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package 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} object) that all of its members must implement. |
| * |
| * <p>The set of categories supported is limited |
| * to the following standard Image I/O service types: |
| * |
| * <ul> |
| * <li>{@link ImageInputStreamSpi} |
| * <li>{@link ImageOutputStreamSpi} |
| * <li>{@link ImageReaderSpi} |
| * <li>{@link ImageTranscoderSpi} |
| * <li>{@link ImageWriterSpi} |
| * </ul> |
| * |
| * <p>An attempt to load a provider that is not a subtype of one of the |
| * above types will result in {@code IllegalArgumentException}. For |
| * a general mechanism to load service providers, see |
| * {@link java.util.ServiceLoader ServiceLoader}. |
| * |
| * <p> Only a single instance of a given leaf class (that is, the |
| * actual class returned by {@code getClass()}, as opposed to any |
| * inherited classes or interfaces) may be registered. That is, |
| * suppose that the |
| * {@code com.mycompany.mypkg.GreenImageReaderProvider} class |
| * is a subclass of {@code javax.imageio.spi.ImageReaderSpi}. |
| * If a {@code GreenImageReaderProvider} instance is |
| * registered, it will be stored in the category defined by the |
| * {@code ImageReaderSpi} class. If a new instance of |
| * {@code GreenImageReaderProvider} 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} |
| * subdirectory is placed within the {@code META-INF} 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.GreenImageReaderProvider} which implements the |
| * {@code javax.imageio.spi.ImageReaderSpi} interface, the JAR file |
| * would contain a file named: <pre> |
| * META-INF/services/javax.imageio.spi.ImageReaderSpi</pre> |
| * |
| * containing the line: |
| * |
| * <pre> |
| * com.mycompany.mypkg.GreenImageReaderProvider |
| * </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="{@docRoot}/../specs/jar/jar.html">JAR File Specification</a>. |
| * |
| * @see RegisterableService |
| * @see java.util.ServiceLoader |
| */ |
| public class ServiceRegistry { |
| |
| // Class -> Registry |
| private Map<Class<?>, SubRegistry> categoryMap = new HashMap<>(); |
| |
| /** |
| * Constructs a {@code ServiceRegistry} instance with a |
| * set of categories taken from the {@code categories} |
| * argument. The categories must all be members of the set |
| * of service types listed in the class specification. |
| * |
| * @param categories an {@code Iterator} containing |
| * {@code Class} objects to be used to define categories. |
| * |
| * @exception IllegalArgumentException if |
| * {@code categories} is {@code null}, or if |
| * one of the categories is not an allowed service type. |
| */ |
| public ServiceRegistry(Iterator<Class<?>> categories) { |
| if (categories == null) { |
| throw new IllegalArgumentException("categories == null!"); |
| } |
| while (categories.hasNext()) { |
| Class<?> category = categories.next(); |
| checkClassAllowed(category); |
| SubRegistry reg = new SubRegistry(this, category); |
| categoryMap.put(category, reg); |
| } |
| } |
| |
| /** |
| * Searches for implementations of a particular service class |
| * using the given class loader. |
| * |
| * <p>The service class must be one of the service types listed |
| * in the class specification. If it is not, {@code IllegalArgumentException} |
| * will be thrown. |
| * |
| * <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} |
| * 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} 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} if the system class loader (or, failing that |
| * the bootstrap class loader) is to be used. |
| * |
| * @param <T> the type of the providerClass. |
| * |
| * @return An {@code Iterator} that yields provider objects |
| * for the given service, in some arbitrary order. The iterator |
| * will throw an {@code Error} if a provider-configuration |
| * file violates the specified format or if a provider class |
| * cannot be found and instantiated. |
| * |
| * @exception IllegalArgumentException if |
| * {@code providerClass} is {@code null}, or if it is |
| * not one of the allowed service types. |
| */ |
| public static <T> Iterator<T> lookupProviders(Class<T> providerClass, |
| ClassLoader loader) |
| { |
| if (providerClass == null) { |
| throw new IllegalArgumentException("providerClass == null!"); |
| } |
| checkClassAllowed(providerClass); |
| 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> |
| * |
| * <p>The service class must be one of the service types listed |
| * in the class specification. If it is not, {@code IllegalArgumentException} |
| * will be thrown. |
| * |
| * @param providerClass a {@code Class} object indicating the |
| * class or interface of the service providers being detected. |
| * |
| * @param <T> the type of the providerClass. |
| * |
| * @return An {@code Iterator} that yields provider objects |
| * for the given service, in some arbitrary order. The iterator |
| * will throw an {@code Error} if a provider-configuration |
| * file violates the specified format or if a provider class |
| * cannot be found and instantiated. |
| * |
| * @exception IllegalArgumentException if |
| * {@code providerClass} is {@code null}, or if it is |
| * not one of the allowed service types. |
| */ |
| public static <T> Iterator<T> lookupProviders(Class<T> providerClass) { |
| if (providerClass == null) { |
| throw new IllegalArgumentException("providerClass == null!"); |
| } |
| checkClassAllowed(providerClass); |
| return ServiceLoader.load(providerClass).iterator(); |
| } |
| |
| /** |
| * Returns an {@code Iterator} of {@code Class} objects |
| * indicating the current set of categories. The iterator will be |
| * empty if no categories exist. |
| * |
| * @return an {@code Iterator} containing |
| * {@code Class} objects. |
| */ |
| public Iterator<Class<?>> getCategories() { |
| Set<Class<?>> keySet = categoryMap.keySet(); |
| return keySet.iterator(); |
| } |
| |
| /** |
| * Returns an Iterator containing the subregistries to which the |
| * provider belongs. |
| */ |
| private Iterator<SubRegistry> getSubRegistries(Object provider) { |
| List<SubRegistry> l = new ArrayList<>(); |
| Iterator<Class<?>> iter = categoryMap.keySet().iterator(); |
| while (iter.hasNext()) { |
| Class<?> c = iter.next(); |
| if (c.isAssignableFrom(provider.getClass())) { |
| l.add(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} implements the |
| * {@code RegisterableService} interface, its |
| * {@code onRegistration} method will be called. Its |
| * {@code onDeregistration} 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. |
| * @param <T> the type of the provider. |
| * |
| * @return true if no provider of the same class was previously |
| * registered in the same category category. |
| * |
| * @exception IllegalArgumentException if {@code provider} is |
| * {@code null}. |
| * @exception IllegalArgumentException if there is no category |
| * corresponding to {@code category}. |
| * @exception ClassCastException if provider does not implement |
| * the {@code Class} defined by {@code category}. |
| */ |
| public <T> boolean registerServiceProvider(T provider, |
| Class<T> category) { |
| if (provider == null) { |
| throw new IllegalArgumentException("provider == null!"); |
| } |
| SubRegistry reg = 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} it implements. |
| * |
| * <p> If {@code provider} implements the |
| * {@code RegisterableService} interface, its |
| * {@code onRegistration} method will be called once for each |
| * category it is registered under. Its |
| * {@code onDeregistration} 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} is {@code null}. |
| */ |
| public void registerServiceProvider(Object provider) { |
| if (provider == null) { |
| throw new IllegalArgumentException("provider == null!"); |
| } |
| Iterator<SubRegistry> regs = getSubRegistries(provider); |
| while (regs.hasNext()) { |
| SubRegistry reg = regs.next(); |
| reg.registerServiceProvider(provider); |
| } |
| } |
| |
| /** |
| * Adds a set of service provider objects, taken from an |
| * {@code Iterator} to the registry. Each provider is |
| * associated within each category present in the registry whose |
| * {@code Class} it implements. |
| * |
| * <p> For each entry of {@code providers} that implements |
| * the {@code RegisterableService} interface, its |
| * {@code onRegistration} method will be called once for each |
| * category it is registered under. Its |
| * {@code onDeregistration} 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} |
| * is {@code null} or contains a {@code null} 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} is returned. Otherwise, {@code true} |
| * is returned. If an object of the same class as |
| * {@code provider} but not equal (using {@code ==}) to |
| * {@code provider} is registered, it will not be |
| * deregistered. |
| * |
| * <p> If {@code provider} implements the |
| * {@code RegisterableService} interface, its |
| * {@code onDeregistration} method will be called. |
| * |
| * @param provider the service provider object to be deregistered. |
| * @param category the category from which to deregister the |
| * provider. |
| * @param <T> the type of the provider. |
| * |
| * @return {@code true} if the provider was previously |
| * registered in the same category category, |
| * {@code false} otherwise. |
| * |
| * @exception IllegalArgumentException if {@code provider} is |
| * {@code null}. |
| * @exception IllegalArgumentException if there is no category |
| * corresponding to {@code category}. |
| * @exception ClassCastException if provider does not implement |
| * the class defined by {@code category}. |
| */ |
| public <T> boolean deregisterServiceProvider(T provider, |
| Class<T> category) { |
| if (provider == null) { |
| throw new IllegalArgumentException("provider == null!"); |
| } |
| SubRegistry reg = 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} is |
| * {@code null}. |
| */ |
| public void deregisterServiceProvider(Object provider) { |
| if (provider == null) { |
| throw new IllegalArgumentException("provider == null!"); |
| } |
| Iterator<SubRegistry> regs = getSubRegistries(provider); |
| while (regs.hasNext()) { |
| SubRegistry reg = regs.next(); |
| reg.deregisterServiceProvider(provider); |
| } |
| } |
| |
| /** |
| * Returns {@code true} if {@code provider} is currently |
| * registered. |
| * |
| * @param provider the service provider object to be queried. |
| * |
| * @return {@code true} if the given provider has been |
| * registered. |
| * |
| * @exception IllegalArgumentException if {@code provider} is |
| * {@code null}. |
| */ |
| public boolean contains(Object provider) { |
| if (provider == null) { |
| throw new IllegalArgumentException("provider == null!"); |
| } |
| Iterator<SubRegistry> regs = getSubRegistries(provider); |
| while (regs.hasNext()) { |
| SubRegistry reg = regs.next(); |
| if (reg.contains(provider)) { |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| /** |
| * Returns an {@code Iterator} containing all registered |
| * service providers in the given category. If |
| * {@code useOrdering} is {@code false}, 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} if pairwise orderings |
| * should be taken account in ordering the returned objects. |
| * @param <T> the type of the category. |
| * |
| * @return an {@code Iterator} containing service provider |
| * objects from the given category, possibly in order. |
| * |
| * @exception IllegalArgumentException if there is no category |
| * corresponding to {@code category}. |
| */ |
| public <T> Iterator<T> getServiceProviders(Class<T> category, |
| boolean useOrdering) { |
| SubRegistry reg = categoryMap.get(category); |
| if (reg == null) { |
| throw new IllegalArgumentException("category unknown!"); |
| } |
| @SuppressWarnings("unchecked") |
| Iterator<T> it = (Iterator<T>)reg.getServiceProviders(useOrdering); |
| return it; |
| } |
| |
| /** |
| * A simple filter interface used by |
| * {@code ServiceRegistry.getServiceProviders} to select |
| * providers matching an arbitrary criterion. Classes that |
| * implement this interface should be defined in order to make use |
| * of the {@code getServiceProviders} method of |
| * {@code ServiceRegistry} that takes a {@code Filter}. |
| * |
| * @see ServiceRegistry#getServiceProviders(Class, ServiceRegistry.Filter, boolean) |
| */ |
| public interface Filter { |
| |
| /** |
| * Returns {@code true} if the given |
| * {@code provider} object matches the criterion defined |
| * by this {@code Filter}. |
| * |
| * @param provider a service provider {@code Object}. |
| * |
| * @return true if the provider matches the criterion. |
| */ |
| boolean filter(Object provider); |
| } |
| |
| /** |
| * Returns an {@code Iterator} containing service provider |
| * objects within a given category that satisfy a criterion |
| * imposed by the supplied {@code ServiceRegistry.Filter} |
| * object's {@code filter} method. |
| * |
| * <p> The {@code useOrdering} argument controls the |
| * ordering of the results using the same rules as |
| * {@code getServiceProviders(Class, boolean)}. |
| * |
| * @param category the category to be retrieved from. |
| * @param filter an instance of {@code ServiceRegistry.Filter} |
| * whose {@code filter} method will be invoked. |
| * @param useOrdering {@code true} if pairwise orderings |
| * should be taken account in ordering the returned objects. |
| * @param <T> the type of the category. |
| * |
| * @return an {@code Iterator} containing service provider |
| * objects from the given category, possibly in order. |
| * |
| * @exception IllegalArgumentException if there is no category |
| * corresponding to {@code category}. |
| */ |
| public <T> Iterator<T> getServiceProviders(Class<T> category, |
| Filter filter, |
| boolean useOrdering) { |
| SubRegistry reg = categoryMap.get(category); |
| if (reg == null) { |
| throw new IllegalArgumentException("category unknown!"); |
| } |
| Iterator<T> 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} |
| * is returned. |
| * |
| * @param providerClass the {@code Class} of the desired |
| * service provider object. |
| * @param <T> the type of the provider. |
| * |
| * @return a currently registered service provider object with the |
| * desired {@code Class} type, or {@code null} is none is |
| * present. |
| * |
| * @exception IllegalArgumentException if {@code providerClass} is |
| * {@code null}. |
| */ |
| public <T> T getServiceProviderByClass(Class<T> providerClass) { |
| if (providerClass == null) { |
| throw new IllegalArgumentException("providerClass == null!"); |
| } |
| Iterator<Class<?>> iter = categoryMap.keySet().iterator(); |
| while (iter.hasNext()) { |
| Class<?> c = iter.next(); |
| if (c.isAssignableFrom(providerClass)) { |
| SubRegistry reg = 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} 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} methods when their |
| * {@code useOrdering} argument is {@code true}. |
| * |
| * @param category a {@code Class} 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} is preferred. |
| * @param <T> the type of the category. |
| * |
| * @return {@code true} if a previously unset ordering |
| * was established. |
| * |
| * @exception IllegalArgumentException if either provider is |
| * {@code null} or they are the same object. |
| * @exception IllegalArgumentException if there is no category |
| * corresponding to {@code category}. |
| */ |
| 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 = 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} is returned. |
| * |
| * <p> The ordering will be used by the |
| * {@code getServiceProviders} methods when their |
| * {@code useOrdering} argument is {@code true}. |
| * |
| * @param category a {@code Class} 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} was formerly preferred. |
| * @param <T> the type of the category. |
| * |
| * @return {@code true} if a previously set ordering was |
| * disestablished. |
| * |
| * @exception IllegalArgumentException if either provider is |
| * {@code null} or they are the same object. |
| * @exception IllegalArgumentException if there is no category |
| * corresponding to {@code category}. |
| */ |
| 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 = 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}. |
| */ |
| public void deregisterAll(Class<?> category) { |
| SubRegistry reg = 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<SubRegistry> iter = categoryMap.values().iterator(); |
| while (iter.hasNext()) { |
| SubRegistry reg = iter.next(); |
| reg.clear(); |
| } |
| } |
| |
| /** |
| * Finalizes this object prior to garbage collection. The |
| * {@code deregisterAll} 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. |
| * |
| * @deprecated The {@code finalize} method has been deprecated. |
| * Subclasses that override {@code finalize} in order to perform cleanup |
| * should be modified to use alternative cleanup mechanisms and |
| * to remove the overriding {@code finalize} method. |
| * When overriding the {@code finalize} method, its implementation must explicitly |
| * ensure that {@code super.finalize()} is invoked as described in {@link Object#finalize}. |
| * See the specification for {@link Object#finalize()} for further |
| * information about migration options. |
| */ |
| @Deprecated(since="9") |
| public void finalize() throws Throwable { |
| deregisterAll(); |
| super.finalize(); |
| } |
| |
| /** |
| * Checks whether the provided class is one of the allowed |
| * ImageIO service provider classes. If it is, returns normally. |
| * If it is not, throws IllegalArgumentException. |
| * |
| * @param clazz |
| * @throws IllegalArgumentException if clazz is null or is not one of the allowed set |
| */ |
| private static void checkClassAllowed(Class<?> clazz) { |
| if (clazz == null) { |
| throw new IllegalArgumentException("class must not be null"); |
| } |
| |
| if ( clazz != ImageInputStreamSpi.class |
| && clazz != ImageOutputStreamSpi.class |
| && clazz != ImageReaderSpi.class |
| && clazz != ImageTranscoderSpi.class |
| && clazz != ImageWriterSpi.class) { |
| throw new IllegalArgumentException(clazz.getName() + " is not an ImageIO SPI class"); |
| } |
| } |
| } |
| |
| |
| /** |
| * 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<Object> poset = new PartiallyOrderedSet<>(); |
| |
| // Class -> Provider Object of that class |
| // No way to express heterogeneous map, we want |
| // Map<Class<T>, T>, where T is ? |
| Map<Class<?>, Object> map = new HashMap<>(); |
| |
| public SubRegistry(ServiceRegistry registry, Class<?> category) { |
| this.registry = registry; |
| this.category = category; |
| } |
| |
| public synchronized 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; |
| try { |
| rs.onRegistration(registry, category); |
| } catch (Throwable t) { |
| System.err.println("Caught and handled this exception :"); |
| t.printStackTrace(); |
| } |
| } |
| |
| return !present; |
| } |
| |
| /** |
| * If the provider was not previously registered, do nothing. |
| * |
| * @return true if the provider was previously registered. |
| */ |
| public synchronized 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 synchronized boolean contains(Object provider) { |
| Object oprovider = map.get(provider.getClass()); |
| return oprovider == provider; |
| } |
| |
| public synchronized boolean setOrdering(Object firstProvider, |
| Object secondProvider) { |
| return poset.setOrdering(firstProvider, secondProvider); |
| } |
| |
| public synchronized boolean unsetOrdering(Object firstProvider, |
| Object secondProvider) { |
| return poset.unsetOrdering(firstProvider, secondProvider); |
| } |
| |
| public synchronized Iterator<Object> getServiceProviders |
| (boolean useOrdering) { |
| if (useOrdering) { |
| return poset.iterator(); |
| } else { |
| return map.values().iterator(); |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| public synchronized <T> T getServiceProviderByClass |
| (Class<T> providerClass) { |
| return (T)map.get(providerClass); |
| } |
| |
| public synchronized void clear() { |
| Iterator<Object> 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(); |
| } |
| |
| @SuppressWarnings("deprecation") |
| public synchronized void finalize() { |
| clear(); |
| } |
| } |
| |
| |
| /** |
| * A class for wrapping {@code Iterators} with a filter function. |
| * This provides an iterator for a subset without duplication. |
| */ |
| class FilterIterator<T> implements Iterator<T> { |
| |
| private Iterator<? extends T> iter; |
| private ServiceRegistry.Filter filter; |
| |
| private T next = null; |
| |
| public FilterIterator(Iterator<? extends 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(); |
| } |
| } |