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.protobuf;
17
18 import static org.jboss.netty.buffer.ChannelBuffers.*;
19
20 import org.jboss.netty.buffer.ChannelBuffer;
21 import org.jboss.netty.channel.Channel;
22 import org.jboss.netty.channel.ChannelHandlerContext;
23 import org.jboss.netty.channel.ChannelPipeline;
24 import org.jboss.netty.channel.MessageEvent;
25 import org.jboss.netty.channel.ChannelHandler.Sharable;
26 import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
27 import org.jboss.netty.handler.codec.frame.LengthFieldPrepender;
28 import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;
29
30 import com.google.protobuf.Message;
31 import com.google.protobuf.MessageLite;
32
33 /**
34 * Encodes the requested <a href="http://code.google.com/p/protobuf/">Google
35 * Protocol Buffers</a> {@link Message} and {@link MessageLite} into a
36 * {@link ChannelBuffer}. A typical setup for TCP/IP would be:
37 * <pre>
38 * {@link ChannelPipeline} pipeline = ...;
39 *
40 * // Decoders
41 * pipeline.addLast("frameDecoder",
42 * new {@link LengthFieldBasedFrameDecoder}(1048576, 0, 4, 0, 4));
43 * pipeline.addLast("protobufDecoder",
44 * new {@link ProtobufDecoder}(MyMessage.getDefaultInstance()));
45 *
46 * // Encoder
47 * pipeline.addLast("frameEncoder", new {@link LengthFieldPrepender}(4));
48 * pipeline.addLast("protobufEncoder", new {@link ProtobufEncoder}());
49 * </pre>
50 * and then you can use a {@code MyMessage} instead of a {@link ChannelBuffer}
51 * as a message:
52 * <pre>
53 * void messageReceived({@link ChannelHandlerContext} ctx, {@link MessageEvent} e) {
54 * MyMessage req = (MyMessage) e.getMessage();
55 * MyMessage res = MyMessage.newBuilder().setText(
56 * "Did you say '" + req.getText() + "'?").build();
57 * ch.write(res);
58 * }
59 * </pre>
60 *
61 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
62 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
63 *
64 * @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
65 *
66 * @apiviz.landmark
67 */
68 @Sharable
69 public class ProtobufEncoder extends OneToOneEncoder {
70
71 /**
72 * Creates a new instance.
73 */
74 public ProtobufEncoder() {
75 super();
76 }
77
78 @Override
79 protected Object encode(
80 ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
81 if (msg instanceof MessageLite) {
82 return wrappedBuffer(((MessageLite) msg).toByteArray());
83 }
84 if (msg instanceof MessageLite.Builder) {
85 return wrappedBuffer(((MessageLite.Builder) msg).build().toByteArray());
86 }
87 return msg;
88 }
89 }