1 /*
2 * Copyright 2009 Red Hat, Inc.
3 *
4 * Red Hat licenses this file to you under the Apache License, version 2.0
5 * (the "License"); you may not use this file except in compliance with the
6 * License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package org.jboss.netty.handler.codec.serialization;
17
18 import java.io.ObjectOutputStream;
19 import java.io.StreamCorruptedException;
20
21 import org.jboss.netty.buffer.ChannelBuffer;
22 import org.jboss.netty.buffer.ChannelBufferInputStream;
23 import org.jboss.netty.channel.Channel;
24 import org.jboss.netty.channel.ChannelHandlerContext;
25 import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
26
27 /**
28 * A decoder which deserializes the received {@link ChannelBuffer}s into Java
29 * objects.
30 * <p>
31 * Please note that the serialized form this decoder expects is not
32 * compatible with the standard {@link ObjectOutputStream}. Please use
33 * {@link ObjectEncoder} or {@link ObjectEncoderOutputStream} to ensure the
34 * interoperability with this decoder.
35 *
36 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
37 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
38 *
39 * @version $Rev: 2279 $, $Date: 2010-05-13 23:13:07 +0900 (Thu, 13 May 2010) $
40 *
41 * @apiviz.landmark
42 * @apiviz.has org.jboss.netty.handler.codec.serialization.ObjectDecoderInputStream - - - compatible with
43 */
44 public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
45
46 private final ClassLoader classLoader;
47
48 /**
49 * Creates a new decoder whose maximum object size is {@code 1048576}
50 * bytes. If the size of the received object is greater than
51 * {@code 1048576} bytes, a {@link StreamCorruptedException} will be
52 * raised.
53 */
54 public ObjectDecoder() {
55 this(1048576);
56 }
57
58 /**
59 * Creates a new decoder with the specified maximum object size.
60 *
61 * @param maxObjectSize the maximum byte length of the serialized object.
62 * if the length of the received object is greater
63 * than this value, {@link StreamCorruptedException}
64 * will be raised.
65 */
66 public ObjectDecoder(int maxObjectSize) {
67 this(maxObjectSize, null);
68 }
69
70 /**
71 * Creates a new decoder with the specified maximum object size.
72 *
73 * @param maxObjectSize the maximum byte length of the serialized object.
74 * if the length of the received object is greater
75 * than this value, {@link StreamCorruptedException}
76 * will be raised.
77 * @param classLoader the {@link ClassLoader} which will load the class
78 * of the serialized object
79 */
80 public ObjectDecoder(int maxObjectSize, ClassLoader classLoader) {
81 super(maxObjectSize, 0, 4, 0, 4);
82 this.classLoader = classLoader;
83 }
84
85 @Override
86 protected Object decode(
87 ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) throws Exception {
88
89 ChannelBuffer frame = (ChannelBuffer) super.decode(ctx, channel, buffer);
90 if (frame == null) {
91 return null;
92 }
93
94 return new CompactObjectInputStream(
95 new ChannelBufferInputStream(frame), classLoader).readObject();
96 }
97
98 @Override
99 protected ChannelBuffer extractFrame(ChannelBuffer buffer, int index, int length) {
100 return buffer.slice(index, length);
101 }
102 }