netty(一)--一个简单的Netty使用例子

maven依赖：

    <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.29.Final</version>
        </dependency>

服务端：

package cn.nn.t2;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

public class EchoServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf in= (ByteBuf) msg;
        System.out.println("Server received: "+in.toString(CharsetUtil.UTF_8));
        ctx.write(in);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

package cn.nn.t2;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

import java.net.InetSocketAddress;

public class EchoServer {
    private final int port;

    public EchoServer(int port) {
        this.port = port;
    }

    public static void main(String[] args) throws InterruptedException {
        if (args.length!=1){
            System.err.println("Usage: "+
                    EchoServer.class.getSimpleName()+" <port>"
            );
        }
        int port=Integer.parseInt(args[0]);
        new EchoServer(port).start();
    }

    public void start() throws InterruptedException {
        final  EchoServerHandler echoServerHandler=new EchoServerHandler();
        EventLoopGroup group=new NioEventLoopGroup();
        try {
            ServerBootstrap serverBootstrap=new ServerBootstrap();
            serverBootstrap.group(group)
                    .channel(NioServerSocketChannel.class)//使用指定的NIO传输channel
                    .localAddress(new InetSocketAddress(port))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(echoServerHandler);
                        }
                    });
            ChannelFuture f=serverBootstrap.bind().sync();
            f.channel().closeFuture().sync();
        }finally {
            group.shutdownGracefully().sync();
        }
    }
}

客户端：

package cn.nn.t2;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.util.CharsetUtil;

public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> {
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf) throws Exception {
        System.out.println("Client received: "+byteBuf.toString(CharsetUtil.UTF_8));
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush(Unpooled.copiedBuffer("netty rocks",CharsetUtil.UTF_8));
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

package cn.nn.t2;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.net.InetSocketAddress;

public class EchoClient {
    private final String host;
    private final int port;

    public EchoClient(String host, int port) {
        this.host = host;
        this.port = port;
    }
    public void start() throws InterruptedException {
        EventLoopGroup group=new NioEventLoopGroup();
        try {
            Bootstrap b=new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .remoteAddress(new InetSocketAddress(host,port))
                    .handler(new ChannelInitializer<SocketChannel>() {
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new EchoClientHandler());
                        }
                    });
            ChannelFuture channelFuture=b.connect().sync();
            channelFuture.channel().closeFuture().sync();
        }finally {
            group.shutdownGracefully().sync();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        if (args.length != 2) {
            System.err.println(
                    "Usage: " + EchoClient.class.getSimpleName() +
                            " <host> <port>");
            return;
        }
        String host = args[0];
        int port = Integer.parseInt(args[1]);
        new EchoClient(host, port).start();
    }
}