1 /*
2 * Copyright (c) 1998, 2005 Gargoyle Software Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright notice,
10 * this list of conditions and the following disclaimer in the documentation
11 * and/or other materials provided with the distribution.
12 * 3. The end-user documentation included with the redistribution, if any, must
13 * include the following acknowledgment:
14 *
15 * "This product includes software developed by Gargoyle Software Inc.
16 * (http://www.GargoyleSoftware.com/)."
17 *
18 * Alternately, this acknowledgment may appear in the software itself, if
19 * and wherever such third-party acknowledgments normally appear.
20 * 4. The name "Gargoyle Software" must not be used to endorse or promote
21 * products derived from this software without prior written permission.
22 * For written permission, please contact info@GargoyleSoftware.com.
23 * 5. Products derived from this software may not be called "GSBase", nor may
24 * "GSBase" appear in their name, without prior written permission of
25 * Gargoyle Software Inc.
26 *
27 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
28 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
29 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GARGOYLE
30 * SOFTWARE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
32 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
33 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
34 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
35 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
36 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 */
38 package com.gargoylesoftware.base.io;
39
40 import java.io.ObjectOutputStream;
41 import java.io.OutputStream;
42 import java.io.IOException;
43 import java.util.List;
44 import java.util.ArrayList;
45
46 /***
47 * A specialized subclass of ObjectOutputStream that is used to serialize
48 * objects. This stream will remove duplicate objects from the stream in
49 * order to shrink the resulting byte stream.<p>
50 *
51 * Only objects of the following types will be condensed: Character, Double,
52 * Integer, Long, Short and String. The biggest benefit will come from
53 * duplicate Strings.
54 *
55 * @version $Revision: 1.4 $
56 * @author <a href="mailto:mbowler@GargoyleSoftware.com">Mike Bowler</a>
57 */
58 public class CondensedObjectOutputStream extends ObjectOutputStream {
59
60 /***
61 * The list of classes that we can try condensing. Only classes that
62 * are immutable should be in this list.
63 */
64 private final String classNames_[] = {
65 "java.lang.Character",
66 "java.lang.Double",
67 "java.lang.Integer",
68 "java.lang.Long",
69 "java.lang.Short",
70 "java.lang.String",
71 };
72
73 private final List classes_;
74 private final List objects_ = new ArrayList();
75
76 /***
77 * Create the stream
78 * @param stream The output stream that we are wrapping
79 * @throws IOException If the superclass throws an IOException in it's
80 * constructor.
81 */
82 public CondensedObjectOutputStream( final OutputStream stream ) throws IOException {
83 super(stream);
84 enableReplaceObject(true);
85
86 classes_ = new ArrayList( classNames_.length );
87 int i;
88 for( i=0; i<classNames_.length; i++ ) {
89 try {
90 classes_.add( Class.forName(classNames_[i]) );
91 }
92 catch( final ClassNotFoundException e ) {
93 // Theoretically impossible if the classNames list is set up correctly.
94 throw new NoClassDefFoundError( classNames_[i] );
95 }
96 }
97
98 }
99
100 /***
101 * Overrides the superclass to perform substitutions of duplicate
102 * immutable objects.
103 *
104 * @param object The object to be serialized
105 * @return Either the object that was passed in or an identical object
106 * that had previously been passed in.
107 */
108 protected Object replaceObject( final Object object ) {
109
110 Object rc = object;
111
112 if( object != null && classes_.contains( object.getClass() ) ) {
113
114 final int index = objects_.indexOf(object);
115 if( index == -1 ) {
116 objects_.add( object );
117 }
118 else {
119 rc = objects_.get(index);
120 }
121 }
122
123 return rc;
124 }
125 }
126