netty入门实例

《Netty 5用户指南》http://ifeve.com/netty5-user-guide/

Netty是一个NIO框架，使用它可以简单快速地开发网络应用程序，比如客户端和服务端的协议。

Netty大大简化了网络程序的开发过程比如TCP和UDP的 Socket的开发。

1、Client.java

package com.yxq.test;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
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.NioSocketChannel;

public class Client {

    public static void main(String[] args) throws Exception {

        EventLoopGroup workgroup = new NioEventLoopGroup();
        Bootstrap b = new Bootstrap();
        b.group(workgroup)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel sc) throws Exception {
                        sc.pipeline().addLast(new ClientHandler());
                    }
                });

        ChannelFuture cf1 = b.connect("127.0.0.1", 8765).sync();

        //buf
        cf1.channel().writeAndFlush(Unpooled.copiedBuffer("777".getBytes()));

        cf1.channel().closeFuture().sync();
        workgroup.shutdownGracefully();

    }
}

2、ClientHandler.java

package com.yxq.test;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;

public class ClientHandler extends ChannelHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
            //do something msg
            ByteBuf buf = (ByteBuf)msg;
            byte[] data = new byte[buf.readableBytes()];
            buf.readBytes(data);
            String request = new String(data, "utf-8");
            System.out.println("Client: " + request);


        } finally {
            ReferenceCountUtil.release(msg);
        }
    }

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

3、Server.java

package com.yxq.test;
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 static void main(String[] args) throws Exception {
        //1 第一个线程组 是用于接收Client端连接的
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        //2 第二个线程组 是用于实际的业务处理操作的
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        //3 创建一个辅助类Bootstrap，就是对我们的Server进行一系列的配置
        ServerBootstrap b = new ServerBootstrap();
        //把俩个工作线程组加入进来
        b.group(bossGroup, workerGroup)
                //我要指定使用NioServerSocketChannel这种类型的通道
                .channel(NioServerSocketChannel.class)
                //一定要使用 childHandler 去绑定具体的 事件处理器
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel sc) throws Exception {
                        sc.pipeline().addLast(new ServerHandler());
                    }
                });

        //绑定指定的端口 进行监听
        ChannelFuture f = b.bind(8765).sync();

        //Thread.sleep(1000000);
        f.channel().closeFuture().sync();

        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();



    }

}

4、ServerHandler.java

package com.yxq.test;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;

public class ServerHandler  extends ChannelHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        //do something msg
        ByteBuf buf = (ByteBuf)msg;
        byte[] data = new byte[buf.readableBytes()];
        buf.readBytes(data);
        String request = new String(data, "utf-8");
        System.out.println("Server: " + request);
        //写给客户端
        String response = "我是反馈的信息";
        ctx.writeAndFlush(Unpooled.copiedBuffer("888".getBytes()));
        //.addListener(ChannelFutureListener.CLOSE);


    }

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

}

打印：

先启server端，再启client端