| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.catalina.webresources; |
| |
| import java.net.URL; |
| import java.net.URLStreamHandler; |
| import java.net.URLStreamHandlerFactory; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.concurrent.CopyOnWriteArrayList; |
| |
| public class TomcatURLStreamHandlerFactory implements URLStreamHandlerFactory { |
| |
| private static final String WAR_PROTOCOL = "war"; |
| |
| // Singleton instance |
| private static volatile TomcatURLStreamHandlerFactory instance = null; |
| |
| /** |
| * Obtain a reference to the singleton instance. It is recommended that |
| * callers check the value of {@link #isRegistered()} before using the |
| * returned instance. |
| */ |
| public static TomcatURLStreamHandlerFactory getInstance() { |
| getInstanceInternal(true); |
| return instance; |
| } |
| |
| |
| private static TomcatURLStreamHandlerFactory getInstanceInternal(boolean register) { |
| // Double checked locking. OK because instance is volatile. |
| if (instance == null) { |
| synchronized (TomcatURLStreamHandlerFactory.class) { |
| if (instance == null) { |
| instance = new TomcatURLStreamHandlerFactory(register); |
| } |
| } |
| } |
| return instance; |
| } |
| |
| |
| private final boolean registered; |
| |
| // List of factories for application defined stream handler factories. |
| private final List<URLStreamHandlerFactory> userFactories = |
| new CopyOnWriteArrayList<>(); |
| |
| /** |
| * Register this factory with the JVM. May be called more than once. The |
| * implementation ensures that registration only occurs once. |
| * |
| * @return <code>true</code> if the factory is already registered with the |
| * JVM or was successfully registered as a result of this call. |
| * <code>false</code> if the factory was disabled prior to this |
| * call. |
| */ |
| public static boolean register() { |
| return getInstanceInternal(true).isRegistered(); |
| } |
| |
| |
| /** |
| * Prevent this this factory from registering with the JVM. May be called |
| * more than once. |
| * |
| * @return <code>true</code> if the factory is already disabled or was |
| * successfully disabled as a result of this call. |
| * <code>false</code> if the factory was already registered prior |
| * to this call. |
| |
| */ |
| public static boolean disable() { |
| return !getInstanceInternal(false).isRegistered(); |
| } |
| |
| |
| /** |
| * Release references to any user provided factories that have been loaded |
| * using the provided class loader. Called during web application stop to |
| * prevent memory leaks. |
| */ |
| public static void release(ClassLoader classLoader) { |
| Iterator<URLStreamHandlerFactory> iter = instance.userFactories.iterator(); |
| while (iter.hasNext()) { |
| ClassLoader factoryLoader = iter.next().getClass().getClassLoader(); |
| while (factoryLoader != null) { |
| if (classLoader.equals(factoryLoader)) { |
| iter.remove(); |
| break; |
| } |
| factoryLoader = factoryLoader.getParent(); |
| } |
| } |
| } |
| |
| |
| private TomcatURLStreamHandlerFactory(boolean register) { |
| // Hide default constructor |
| // Singleton pattern to ensure there is only one instance of this |
| // factory |
| this.registered = register; |
| if (register) { |
| URL.setURLStreamHandlerFactory(this); |
| } |
| } |
| |
| |
| public boolean isRegistered() { |
| return registered; |
| } |
| |
| |
| /** |
| * Since the JVM only allows a single call to |
| * {@link URL#setURLStreamHandlerFactory(URLStreamHandlerFactory)} and |
| * Tomcat needs to register a handler, provide a mechanism to allow |
| * applications to register their own handlers. |
| */ |
| public void addUserFactory(URLStreamHandlerFactory factory) { |
| userFactories.add(factory); |
| } |
| |
| |
| @Override |
| public URLStreamHandler createURLStreamHandler(String protocol) { |
| |
| // Tomcat's handler always takes priority so applications can't override |
| // it. |
| if (WAR_PROTOCOL.equals(protocol)) { |
| return new WarURLStreamHandler(); |
| } |
| |
| // Application handlers |
| for (URLStreamHandlerFactory factory : userFactories) { |
| URLStreamHandler handler = |
| factory.createURLStreamHandler(protocol); |
| if (handler != null) { |
| return handler; |
| } |
| } |
| |
| // Unknown protocol |
| return null; |
| } |
| } |