1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the 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 io.netty.handler.codec.protobuf;
17
18 import com.google.protobuf.Message;
19 import com.google.protobuf.MessageLite;
20 import com.google.protobuf.MessageLiteOrBuilder;
21 import io.netty.buffer.ByteBuf;
22 import io.netty.channel.ChannelHandler.Sharable;
23 import io.netty.channel.ChannelHandlerContext;
24 import io.netty.channel.ChannelPipeline;
25 import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
26 import io.netty.handler.codec.LengthFieldPrepender;
27 import io.netty.handler.codec.MessageToMessageEncoder;
28
29 import java.util.List;
30
31 import static io.netty.buffer.Unpooled.*;
32
33 /**
34 * Encodes the requested <a href="https://github.com/google/protobuf">Google
35 * Protocol Buffers</a> {@link Message} and {@link MessageLite} into a
36 * {@link ByteBuf}. 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 ByteBuf}
51 * as a message:
52 * <pre>
53 * void channelRead({@link ChannelHandlerContext} ctx, MyMessage req) {
54 * MyMessage res = MyMessage.newBuilder().setText(
55 * "Did you say '" + req.getText() + "'?").build();
56 * ch.write(res);
57 * }
58 * </pre>
59 */
60 @Sharable
61 public class ProtobufEncoder extends MessageToMessageEncoder<MessageLiteOrBuilder> {
62 @Override
63 protected void encode(
64 ChannelHandlerContext ctx, MessageLiteOrBuilder msg, List<Object> out) throws Exception {
65 if (msg instanceof MessageLite) {
66 out.add(wrappedBuffer(((MessageLite) msg).toByteArray()));
67 return;
68 }
69 if (msg instanceof MessageLite.Builder) {
70 out.add(wrappedBuffer(((MessageLite.Builder) msg).build().toByteArray()));
71 }
72 }
73 }