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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    * 
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   * 
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.io.input;
18  
19  import java.io.IOException;
20  import java.io.InputStream;
21  import java.io.ObjectInputStream;
22  import java.io.ObjectStreamClass;
23  import java.io.StreamCorruptedException;
24  
25  /**
26   * A special ObjectInputStream that loads a class based on a specified
27   * <code>ClassLoader</code> rather than the system default.
28   * <p>
29   * This is useful in dynamic container environments.
30   *
31   * @author Paul Hammant
32   * @version $Id: ClassLoaderObjectInputStream.java 437567 2006-08-28 06:39:07Z bayard $
33   * @since Commons IO 1.1
34   */
35  public class ClassLoaderObjectInputStream extends ObjectInputStream {
36  
37      /** The class loader to use. */
38      private ClassLoader classLoader;
39  
40      /**
41       * Constructs a new ClassLoaderObjectInputStream.
42       *
43       * @param classLoader  the ClassLoader from which classes should be loaded
44       * @param inputStream  the InputStream to work on
45       * @throws IOException in case of an I/O error
46       * @throws StreamCorruptedException if the stream is corrupted
47       */
48      public ClassLoaderObjectInputStream(
49              ClassLoader classLoader, InputStream inputStream)
50              throws IOException, StreamCorruptedException {
51          super(inputStream);
52          this.classLoader = classLoader;
53      }
54  
55      /**
56       * Resolve a class specified by the descriptor using the
57       * specified ClassLoader or the super ClassLoader.
58       *
59       * @param objectStreamClass  descriptor of the class
60       * @return the Class object described by the ObjectStreamClass
61       * @throws IOException in case of an I/O error
62       * @throws ClassNotFoundException if the Class cannot be found
63       */
64      protected Class resolveClass(ObjectStreamClass objectStreamClass)
65              throws IOException, ClassNotFoundException {
66          
67          Class clazz = Class.forName(objectStreamClass.getName(), false, classLoader);
68  
69          if (clazz != null) {
70              // the classloader knows of the class
71              return clazz;
72          } else {
73              // classloader knows not of class, let the super classloader do it
74              return super.resolveClass(objectStreamClass);
75          }
76      }
77  }