nio之netty3的应用

　　1、netty3是nio的封装版本。在使用上面比nio的直接使用更好。nio简单使用都是单线程的方式（比如：一个服务员服务很多客户），但是netty3的方式不一样的是，引入线程池的方式来实现服务的通信（比如：不同的服务员服务不同的客户群体一样）。netty3将入口和实现分成两个线程池。入口：boss，实现：work。实现过程就是当一个客户端进入过后，boss线程池分配一个线程来接待客户，而通过boss来分配具体的服务人work来服务这位客户。

　　2、netty3的使用是在nio的基础上加入线程池的概念进行实现的，后面我会单独讲一个netty3的源码实现过程。

　　3、这里写了一点netty3的实现过程。

　　1）服务端：server和serverHandler

import org.jboss.netty.bootstrap.ServerBootstrap;
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.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.ExecutorService;
import java.util.concurrent.Executors;

public class Server {

    public static void main(String[] args) {

        //声明服务类
        ServerBootstrap serverBootstrap = new ServerBootstrap();

        //设定线程池
        ExecutorService boss = Executors.newCachedThreadPool();
        ExecutorService work = Executors.newCachedThreadPool();

        //设置工厂
        serverBootstrap.setFactory(new NioServerSocketChannelFactory(boss,work));

        //设置管道流
        serverBootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            @Override
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline channelPipeline = Channels.pipeline();
                //添加处理方式
                channelPipeline.addLast("decode",new StringDecoder());
                channelPipeline.addLast("encode",new StringEncoder());
                channelPipeline.addLast("server",new ServerHandler());
                return channelPipeline;
            }
        });

        //设置端口
        serverBootstrap.bind(new InetSocketAddress(9000));
    }
}

　　备注：具体的数据处理交给ServerHandler

import org.jboss.netty.channel.*;

public class ServerHandler extends SimpleChannelHandler {

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        System.out.println("client:"+e.getMessage());
        ctx.getChannel().write(e.getMessage());
        super.messageReceived(ctx, e);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
        super.exceptionCaught(ctx, e);
    }

    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        super.channelConnected(ctx, e);
    }

    @Override
    public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        super.channelDisconnected(ctx, e);
    }

    @Override
    public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        super.channelClosed(ctx, e);
    }
}

　　2）客户端：client和clientHandler

import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.*;
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.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Client {

    public static void main(String[] args) {

        //声明客户端
        ClientBootstrap clientBootstrap = new ClientBootstrap();

        //设置线程池
        ExecutorService boss = Executors.newCachedThreadPool();
        ExecutorService work = Executors.newCachedThreadPool();

        //设置线程池工厂
        clientBootstrap.setFactory(new NioClientSocketChannelFactory(boss,work));

        //设置管道工厂
        clientBootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            @Override
            public ChannelPipeline getPipeline() throws Exception {
                ChannelPipeline channelPipeline = Channels.pipeline();
                channelPipeline.addLast("decode",new StringDecoder());
                channelPipeline.addLast("encode",new StringEncoder());
                channelPipeline.addLast("client",new ClientHandler());
                return channelPipeline;
            }
        });

        //连接服务器
        ChannelFuture channelFuture = clientBootstrap.connect(new InetSocketAddress("localhost", 9000));
        //获取通道
        Channel channel = channelFuture.getChannel();
        //写入数据
        Scanner scanner = new Scanner(System.in);
        while (true) {
            channel.write(scanner.next());
        }
    }
}

　　备注：处理的方式基本上和服务端一样

import org.jboss.netty.channel.*;

public class ClientHandler extends SimpleChannelHandler {

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        System.out.println("server:"+e.getMessage());
        super.messageReceived(ctx, e);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
        super.exceptionCaught(ctx, e);
    }

    @Override
    public void channelConnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        super.channelConnected(ctx, e);
    }

    @Override
    public void channelDisconnected(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        super.channelDisconnected(ctx, e);
    }

    @Override
    public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
        super.channelClosed(ctx, e);
    }
}

　　4、这里讲的是netty3的应用过程，应用线程池来实现具体的工作。这样在效率和时间上面都会得到很大的改善