Netty4.0学习笔记系列之五：自定义通讯协议

Netty中，通讯的双方建立连接后，会把数据按照ByteBuf的方式进行传输，例如http协议中，就是通过HttpRequestDecoder对ByteBuf数据流进行处理，转换成http的对象。基于这个思路，我自定义一种通讯协议：Server和客户端直接传输java对象。

实现的原理是通过Encoder把java对象转换成ByteBuf流进行传输，通过Decoder把ByteBuf转换成java对象进行处理，处理逻辑如下图所示：

传输的java bean为Person：

package com.guowl.testobjcoder;

import java.io.Serializable;

// 必须实现Serializable接口
public class Person implements Serializable{
	private static final long	serialVersionUID	= 1L;
	private String	name;
	private String	sex;
	private int		age;

	public String toString() {
		return "name:" + name + " sex:" + sex + " age:" + age;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
}

Server端类：Server PersonDecoder BusinessHandler

1、Server：启动netty服务

package com.guowl.testobjcoder;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class Server {
	public void start(int port) throws Exception {
		EventLoopGroup bossGroup = new NioEventLoopGroup(); 
		EventLoopGroup workerGroup = new NioEventLoopGroup();
		try {
			ServerBootstrap b = new ServerBootstrap(); 
			b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) 
					.childHandler(new ChannelInitializer() { 
								@Override
								public void initChannel(SocketChannel ch) throws Exception {
									ch.pipeline().addLast(new PersonDecoder());
									ch.pipeline().addLast(new BusinessHandler());
								}
							}).option(ChannelOption.SO_BACKLOG, 128) 
					.childOption(ChannelOption.SO_KEEPALIVE, true); 

			ChannelFuture f = b.bind(port).sync(); 

			f.channel().closeFuture().sync();
		} finally {
			workerGroup.shutdownGracefully();
			bossGroup.shutdownGracefully();
		}
	}

	public static void main(String[] args) throws Exception {
		Server server = new Server();
		server.start(8000);
	}
}

2、PersonDecoder：把ByteBuf流转换成Person对象，其中ByteBufToBytes是读取ButeBuf的工具类，上一篇文章中提到过，在此不在详述。ByteObjConverter是byte和obj的互相转换的工具。

package com.guowl.testobjcoder;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

import com.guowl.utils.ByteBufToBytes;
import com.guowl.utils.ByteObjConverter;

public class PersonDecoder extends ByteToMessageDecoder {
	@Override
	protected void decode(ChannelHandlerContext ctx, ByteBuf in, List