io.netty.handler.codec.protobuf.ProtobufEncoder Maven / Gradle / Ivy
/*
* Copyright 2015 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.handler.codec.protobuf;
import com.google.protobuf.Message;
import com.google.protobuf.MessageLite;
import com.google.protobuf.MessageLiteOrBuilder;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.MessageToMessageEncoder;
import java.util.List;
import static io.netty.buffer.Unpooled.*;
/**
* Encodes the requested Google
* Protocol Buffers {@link Message} and {@link MessageLite} into a
* {@link ByteBuf}. A typical setup for TCP/IP would be:
*
* {@link ChannelPipeline} pipeline = ...;
*
* // Decoders
* pipeline.addLast("frameDecoder",
* new {@link LengthFieldBasedFrameDecoder}(1048576, 0, 4, 0, 4));
* pipeline.addLast("protobufDecoder",
* new {@link ProtobufDecoder}(MyMessage.getDefaultInstance()));
*
* // Encoder
* pipeline.addLast("frameEncoder", new {@link LengthFieldPrepender}(4));
* pipeline.addLast("protobufEncoder", new {@link ProtobufEncoder}());
*
* and then you can use a {@code MyMessage} instead of a {@link ByteBuf}
* as a message:
*
* void channelRead({@link ChannelHandlerContext} ctx, Object msg) {
* MyMessage req = (MyMessage) msg;
* MyMessage res = MyMessage.newBuilder().setText(
* "Did you say '" + req.getText() + "'?").build();
* ch.write(res);
* }
*
*/
@Sharable
public class ProtobufEncoder extends MessageToMessageEncoder {
@Override
protected void encode(ChannelHandlerContext ctx, MessageLiteOrBuilder msg, List