7.3 netty3基本使用

由于dubbo默认使用的是netty3进行通信的，这里简单的列出一个netty3通信的例子。

一 server端

1 Server

package com.hulk.netty.server;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.*;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

public class Server {
    public void start(){
        ChannelFactory factory = new NioServerSocketChannelFactory(
                Executors.newCachedThreadPool(),//boss线程池
                Executors.newCachedThreadPool(),//worker线程池
                8//worker线程数
        );
        ServerBootstrap bootstrap = new ServerBootstrap(factory);
        /**
         * 对于每一个连接channel, server都会调用PipelineFactory为该连接创建一个ChannelPipline
         */
        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline pipeline = Channels.pipeline();
                pipeline.addLast("decoder", new StringDecoder());
                pipeline.addLast("encoder", new StringEncoder());
                pipeline.addLast("handler", new ServerLogicHandler());
                return pipeline;
            }
        });

        Channel channel = bootstrap.bind(new InetSocketAddress("127.0.0.1", 8080));
        System.out.println("server start success!");
    }

    public static void main(String[] args) throws InterruptedException {
        Server server = new Server();
        server.start();
        Thread.sleep(Integer.MAX_VALUE);
    }
}

步骤：

• 首先创建了NioServerSocketChannelFactory：创建boss线程池，创建worker线程池以及worker线程数。（boss线程数默认为1个）
• 创建ServerBootstrap server端启动辅助类
• 为ServerBootstrap设置ChannelPipelineFactory工厂，并为ChannelPipelineFactory将来创建出的ChannelPipeline设置编码器／解码器／事件处理器
• 使用ServerBootstrap绑定监听地址和端口

2 事件处理器ServerLogicHandler

package com.hulk.netty.server;

import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

public class ServerLogicHandler extends SimpleChannelHandler {
    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("连接成功, channel: " + e.getChannel().toString());
    }

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        String msg = (String) e.getMessage();
        System.out.println("接收到了client的消息, msg: " + msg);

        Channel channel = e.getChannel();
        String str = "hi, client";

        channel.write(str);//写消息发给client端
        System.out.println("服务端发送数据: " + str + "完成");
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
        e.getCause().printStackTrace();
        e.getChannel().close();
    }
}

说明：

• 监听与客户端连接成功事件
• 监听接收到来自客户端的消息，之后写回给客户端消息
• 捕捉异常事件

二 client端

1 Client

package com.hulk.netty.client;

import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.ChannelFactory;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

public class Client {
    public static void main(String[] args) {
        ChannelFactory factory = new NioClientSocketChannelFactory(
                Executors.newCachedThreadPool(),
                Executors.newCachedThreadPool(),
                8
        );
        ClientBootstrap bootstrap = new ClientBootstrap(factory);
        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline pipeline = Channels.pipeline();
                pipeline.addLast("decoder", new StringDecoder());
                pipeline.addLast("encoder", new StringEncoder());
                pipeline.addLast("handler", new ClientLogicHandler());
                return pipeline;
            }
        });

        bootstrap.connect(new InetSocketAddress("127.0.0.1", 8080));
        System.out.println("client start success!");
    }
}

步骤：（与Server几乎相同）

• 首先创建了NioClientSocketChannelFactory：创建boss线程池，创建worker线程池以及worker线程数。（boss线程数默认为1个）
• 创建ClientBootstrap client端启动辅助类
• 为ClientBootstrap设置ChannelPipelineFactory工厂，并为ChannelPipelineFactory将来创建出的ChannelPipeline设置编码器／解码器／事件处理器
• 使用ClientBootstrap连接Server端监听的地址和端口

2 ClientLogicHandler

package com.hulk.netty.client;

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.WriteCompletionEvent;

public class ClientLogicHandler extends SimpleChannelHandler {
    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        System.out.println("客户端连接成功!");
        String str = "hi server!";
        e.getChannel().write(str);//异步
    }

    @Override
    public void writeComplete(ChannelHandlerContext ctx, WriteCompletionEvent e) throws Exception {
        System.out.println("客户端写消息完成");
    }

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        String msg = (String) e.getMessage();
        System.out.println("客户端接收到消息, msg: " + msg);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
        e.getCause().printStackTrace();
        e.getChannel().close();
    }
}

说明：

• 监听与服务端连接成功事件，连接成功后，写消息给服务端
• 监听向服务端写消息完成的事件
• 监听接收到来自服务端的消息
• 捕捉异常事件

这就是一个简单的netty3通信的例子，关于netty，后续会读源码。