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 static org.jboss.netty.buffer.ChannelBuffers.*;
19
20 import java.io.ObjectInputStream;
21 import java.io.ObjectOutputStream;
22
23 import org.jboss.netty.buffer.ChannelBuffer;
24 import org.jboss.netty.buffer.ChannelBufferOutputStream;
25 import org.jboss.netty.channel.Channel;
26 import org.jboss.netty.channel.ChannelHandlerContext;
27 import org.jboss.netty.channel.ChannelHandler.Sharable;
28 import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
29
30 /**
31 * An encoder which serializes a Java object into a {@link ChannelBuffer}.
32 * <p>
33 * Please note that the serialized form this encoder produces is not
34 * compatible with the standard {@link ObjectInputStream}. Please use
35 * {@link ObjectDecoder} or {@link ObjectDecoderInputStream} to ensure the
36 * interoperability with this encoder.
37 *
38 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
39 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
40 *
41 * @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
42 *
43 * @apiviz.landmark
44 * @apiviz.has org.jboss.netty.handler.codec.serialization.ObjectEncoderOutputStream - - - compatible with
45 */
46 @Sharable
47 public class ObjectEncoder extends OneToOneEncoder {
48 private static final byte[] LENGTH_PLACEHOLDER = new byte[4];
49
50 private final int estimatedLength;
51
52 /**
53 * Creates a new encoder with the estimated length of 512 bytes.
54 */
55 public ObjectEncoder() {
56 this(512);
57 }
58
59 /**
60 * Creates a new encoder.
61 *
62 * @param estimatedLength
63 * the estimated byte length of the serialized form of an object.
64 * If the length of the serialized form exceeds this value, the
65 * internal buffer will be expanded automatically at the cost of
66 * memory bandwidth. If this value is too big, it will also waste
67 * memory bandwidth. To avoid unnecessary memory copy or allocation
68 * cost, please specify the properly estimated value.
69 */
70 public ObjectEncoder(int estimatedLength) {
71 if (estimatedLength < 0) {
72 throw new IllegalArgumentException(
73 "estimatedLength: " + estimatedLength);
74 }
75 this.estimatedLength = estimatedLength;
76 }
77
78 @Override
79 protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
80 ChannelBufferOutputStream bout =
81 new ChannelBufferOutputStream(dynamicBuffer(
82 estimatedLength, ctx.getChannel().getConfig().getBufferFactory()));
83 bout.write(LENGTH_PLACEHOLDER);
84 ObjectOutputStream oout = new CompactObjectOutputStream(bout);
85 oout.writeObject(msg);
86 oout.flush();
87 oout.close();
88
89 ChannelBuffer encoded = bout.buffer();
90 encoded.setInt(0, encoded.writerIndex() - 4);
91 return encoded;
92 }
93 }