1 //******************************************************************************
2 //
3 // File: MPObjectInputStream.java
4 // Package: edu.rit.mp
5 // Unit: Class edu.rit.mp.MPObjectInputStream
6 //
7 // This Java source file is copyright (C) 2006 by Alan Kaminsky. All rights
8 // reserved. For further information, contact the author, Alan Kaminsky, at
9 // ark@cs.rit.edu.
10 //
11 // This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
12 // software; you can redistribute it and/or modify it under the terms of the GNU
13 // General Public License as published by the Free Software Foundation; either
14 // version 3 of the License, or (at your option) any later version.
15 //
16 // PJ is distributed in the hope that it will be useful, but WITHOUT ANY
17 // WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
18 // A PARTICULAR PURPOSE. See the GNU General Public License for more details.
19 //
20 // Linking this library statically or dynamically with other modules is making a
21 // combined work based on this library. Thus, the terms and conditions of the GNU
22 // General Public License cover the whole combination.
23 //
24 // As a special exception, the copyright holders of this library give you
25 // permission to link this library with independent modules to produce an
26 // executable, regardless of the license terms of these independent modules, and
27 // to copy and distribute the resulting executable under terms of your choice,
28 // provided that you also meet, for each linked independent module, the terms
29 // and conditions of the license of that module. An independent module is a module
30 // which is not derived from or based on this library. If you modify this library,
31 // you may extend this exception to your version of the library, but you are not
32 // obligated to do so. If you do not wish to do so, delete this exception
33 // statement from your version.
34 //
35 // A copy of the GNU General Public License is provided in the file gpl.txt. You
36 // may also obtain a copy of the GNU General Public License on the World Wide
37 // Web at http://www.gnu.org/licenses/gpl.html.
38 //
39 //******************************************************************************
40 package edu.rit.mp;
41
42 import java.io.IOException;
43 import java.io.InputStream;
44 import java.io.ObjectInputStream;
45 import java.io.ObjectStreamClass;
46
47 /**
48 * Class MPObjectInputStream provides an object input stream that can load
49 * classes from an alternate class loader.
50 *
51 * @author Alan Kaminsky
52 * @version 31-Jan-2006
53 */
54 class MPObjectInputStream
55 extends ObjectInputStream {
56
57 // Hidden data members.
58 private ClassLoader myClassLoader;
59
60 // Exported constructors.
61 /**
62 * Create a new MP object input stream. An alternate class loader will not
63 * be used.
64 *
65 * @param in Underlying input stream.
66 * @exception IOException Thrown if an I/O error occurred.
67 * @throws java.io.IOException if any.
68 */
69 public MPObjectInputStream(InputStream in)
70 throws IOException {
71 super(in);
72 }
73
74 /**
75 * Create a new MP object input stream. The given class loader will be used
76 * to load classes; if null, an alternate class loader will not be used.
77 *
78 * @param in Underlying input stream.
79 * @param cl Alternate class loader, or null.
80 * @exception IOException Thrown if an I/O error occurred.
81 * @throws java.io.IOException if any.
82 */
83 public MPObjectInputStream(InputStream in,
84 ClassLoader cl)
85 throws IOException {
86 super(in);
87 myClassLoader = cl;
88 }
89
90 // Hidden operations.
91 /**
92 * {@inheritDoc}
93 *
94 * Load the local class equivalent of the specified stream class
95 * description.
96 * @exception IOException Thrown if an I/O error occurred.
97 * @exception ClassNotFoundException Thrown if the local class could not be
98 * found.
99 */
100 protected Class<?> resolveClass(ObjectStreamClass desc)
101 throws IOException, ClassNotFoundException {
102 try {
103 return super.resolveClass(desc);
104 } catch (ClassNotFoundException exc) {
105 if (myClassLoader != null) {
106 return Class.forName(desc.getName(), false, myClassLoader);
107 } else {
108 throw exc;
109 }
110 }
111 }
112
113 }