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Java > Open Source Codes > com > sleepycat > bind > serial > SerialInput


1 /*-
2  * See the file LICENSE for redistribution information.
3  *
4  * Copyright (c) 2000,2006 Oracle. All rights reserved.
5  *
6  * $Id: SerialInput.java,v 1.18 2006/10/30 21:14:07 bostic Exp $
7  */
8
9 package com.sleepycat.bind.serial;
10
11 import java.io.IOException JavaDoc;
12 import java.io.InputStream JavaDoc;
13 import java.io.ObjectInputStream JavaDoc;
14 import java.io.ObjectStreamClass JavaDoc;
15
16 import com.sleepycat.je.DatabaseException;
17 import com.sleepycat.util.RuntimeExceptionWrapper;
18
19 /**
20  * A specialized <code>ObjectInputStream</code> that gets class description
21  * information from a <code>ClassCatalog</code>. It is used by
22  * <code>SerialBinding</code>.
23  *
24  * <p>This class is used instead of an {@link ObjectInputStream}, which it
25  * extends, to read an object stream written by the {@link SerialOutput} class.
26  * For reading objects from a database normally one of the serial binding
27  * classes is used. {@link SerialInput} is used when an {@link
28  * ObjectInputStream} is needed along with compact storage. A {@link
29  * ClassCatalog} must be supplied, however, to stored shared class
30  * descriptions.</p>
31  *
32  * @author Mark Hayes
33  */
34 public class SerialInput extends ObjectInputStream JavaDoc {
35
36     private ClassCatalog classCatalog;
37     private ClassLoader JavaDoc classLoader;
38
39     /**
40      * Creates a serial input stream.
41      *
42      * @param in is the input stream from which compact serialized objects will
43      * be read.
44      *
45      * @param classCatalog is the catalog containing the class descriptions
46      * for the serialized objects.
47      */
48     public SerialInput(InputStream JavaDoc in, ClassCatalog classCatalog)
49         throws IOException JavaDoc {
50
51         this(in, classCatalog, null);
52     }
53
54     /**
55      * Creates a serial input stream.
56      *
57      * @param in is the input stream from which compact serialized objects will
58      * be read.
59      *
60      * @param classCatalog is the catalog containing the class descriptions
61      * for the serialized objects.
62      *
63      * @param classLoader is the class loader to use, or null if a default
64      * class loader should be used.
65      */
66     public SerialInput(InputStream JavaDoc in,
67                        ClassCatalog classCatalog,
68                        ClassLoader JavaDoc classLoader)
69         throws IOException JavaDoc {
70
71         super(in);
72
73         this.classCatalog = classCatalog;
74         this.classLoader = classLoader;
75     }
76
77     // javadoc is specified elsewhere
78 protected ObjectStreamClass JavaDoc readClassDescriptor()
79         throws IOException JavaDoc, ClassNotFoundException JavaDoc {
80
81         try {
82             byte len = readByte();
83             byte[] id = new byte[len];
84             readFully(id);
85
86             return classCatalog.getClassFormat(id);
87         } catch (DatabaseException e) {
88             /*
89              * Do not throw IOException from here since ObjectOutputStream
90              * will write the exception to the stream, which causes another
91              * call here, etc.
92              */
93             throw new RuntimeExceptionWrapper(e);
94         }
95     }
96
97     // javadoc is specified elsewhere
98 protected Class JavaDoc resolveClass(ObjectStreamClass JavaDoc desc)
99         throws IOException JavaDoc, ClassNotFoundException JavaDoc {
100
101         if (classLoader != null) {
102             try {
103                 return Class.forName(desc.getName(), false, classLoader);
104             } catch (ClassNotFoundException JavaDoc e) {
105                 return super.resolveClass(desc);
106             }
107         } else {
108             return super.resolveClass(desc);
109         }
110     }
111 }
112
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