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
025 /**
026 * A special ObjectInputStream that loads a class based on a specified
027 * <code>ClassLoader</code> rather than the system default.
028 * <p>
029 * This is useful in dynamic container environments.
030 *
031 * @author Paul Hammant
032 * @version $Id: ClassLoaderObjectInputStream.java 736890 2009-01-23 02:02:22Z niallp $
033 * @since Commons IO 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 }