001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     * 
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     * 
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.io.input;
018    
019    import java.io.IOException;
020    import java.io.InputStream;
021    import java.io.ObjectInputStream;
022    import java.io.ObjectStreamClass;
023    import java.io.StreamCorruptedException;
024    import java.lang.reflect.Proxy;
025    
026    /**
027     * A special ObjectInputStream that loads a class based on a specified
028     * <code>ClassLoader</code> rather than the system default.
029     * <p>
030     * This is useful in dynamic container environments.
031     *
032     * @version $Id: ClassLoaderObjectInputStream.java 1304052 2012-03-22 20:55:29Z ggregory $
033     * @since 1.1
034     */
035    public class ClassLoaderObjectInputStream extends ObjectInputStream {
036    
037        /** The class loader to use. */
038        private final ClassLoader classLoader;
039    
040        /**
041         * Constructs a new ClassLoaderObjectInputStream.
042         *
043         * @param classLoader  the ClassLoader from which classes should be loaded
044         * @param inputStream  the InputStream to work on
045         * @throws IOException in case of an I/O error
046         * @throws StreamCorruptedException if the stream is corrupted
047         */
048        public ClassLoaderObjectInputStream(
049                ClassLoader classLoader, InputStream inputStream)
050                throws IOException, StreamCorruptedException {
051            super(inputStream);
052            this.classLoader = classLoader;
053        }
054    
055        /**
056         * Resolve a class specified by the descriptor using the
057         * specified ClassLoader or the super ClassLoader.
058         *
059         * @param objectStreamClass  descriptor of the class
060         * @return the Class object described by the ObjectStreamClass
061         * @throws IOException in case of an I/O error
062         * @throws ClassNotFoundException if the Class cannot be found
063         */
064        @Override
065        protected Class<?> resolveClass(ObjectStreamClass objectStreamClass)
066                throws IOException, ClassNotFoundException {
067            
068            Class<?> clazz = Class.forName(objectStreamClass.getName(), false, classLoader);
069    
070            if (clazz != null) {
071                // the classloader knows of the class
072                return clazz;
073            } else {
074                // classloader knows not of class, let the super classloader do it
075                return super.resolveClass(objectStreamClass);
076            }
077        }
078    
079        /**
080         * Create a proxy class that implements the specified interfaces using
081         * the specified ClassLoader or the super ClassLoader.
082         *
083         * @param interfaces the interfaces to implement
084         * @return a proxy class implementing the interfaces
085         * @throws IOException in case of an I/O error
086         * @throws ClassNotFoundException if the Class cannot be found
087         * @see java.io.ObjectInputStream#resolveProxyClass(java.lang.String[])
088         * @since 2.1
089         */
090        @Override
091        protected Class<?> resolveProxyClass(String[] interfaces) throws IOException,
092                ClassNotFoundException {
093            Class<?>[] interfaceClasses = new Class[interfaces.length];
094            for (int i = 0; i < interfaces.length; i++) {
095                interfaceClasses[i] = Class.forName(interfaces[i], false, classLoader);
096            }
097            try {
098                return Proxy.getProxyClass(classLoader, interfaceClasses);
099            } catch (IllegalArgumentException e) {
100                return super.resolveProxyClass(interfaces);
101            }
102        }
103        
104    }