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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 }
     78