Netty入门实例 TCP服务-蒲公英云

基于Netty开发一个入门程序，主要功能：服务端启动后监听一个端口，客户端启动后会给服务端发送一条消息，服务端收到后通过Handler读取消息，进行处理，读取完通过Handler反馈一条消息给客户端。

服务端：

Server
package com.tech.netty.netty;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
/**
 * @author lw
 * @since 2021/8/11
 **/
public class NettyServer {
    public static void main(String[] args) throws InterruptedException {
        //1 创建两个线程组bossGroup workerGroup
        //2 bossGroup处理客户端连接请求 workerGroup处理客户端数据读写请求
        //3 他们都是事件循环组 默认含有CPU核数*2个事件循环NioEventLoop
        NioEventLoopGroup bossGroup = new NioEventLoopGroup();
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            //创建服务器端启动对象，进行参数配置
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup)  //设置两个线程组
                    .channel(NioServerSocketChannel.class)  //设置服务器端通道为NioServerSocketChannel
                    .option(ChannelOption.SO_BACKLOG, 128) //设置连接队列允许的连接个数
                    .childOption(ChannelOption.SO_KEEPALIVE, true) //设置连接连接状态为活动连接
                    .childHandler(new ChannelInitializer<SocketChannel>() { //给workerGroup NioEventLoop通过管道添加处理器
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new NettyServerHandler());
                        }
                    });
            System.out.println("...服务器 is ready...");
            //启动服务器并绑定一个端口
            ChannelFuture channelFuture = serverBootstrap.bind(6668).sync();
            //对通道的关闭事件进行监听
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}
ServerHandler
package com.tech.netty.netty;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelPipeline;
import io.netty.util.CharsetUtil;
/**
 * @author lw
 * @since 2021/8/11
 **/
//自定义一个Handler
public class NettyServerHandler extends ChannelInboundHandlerAdapter {
    //读取客户端发送的消息
    // ChannelHandlerContext 是一个上下文对象，可以获取通道和管道信息
    // msg 是客户端发送的消息
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("服务器读取线程 "+Thread.currentThread().getName());
        System.out.println("server ctx:"+ctx);
        Channel channel = ctx.channel();
        ChannelPipeline pipeline = ctx.pipeline();
        ByteBuf byteBuf = (ByteBuf) msg;
        System.out.println("客户端发送消息是："+byteBuf.toString(CharsetUtil.UTF_8));
        System.out.println("客户端地址："+channel.remoteAddress());
    }
    //数据读取完毕
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        //发送数据
        ctx.writeAndFlush(Unpooled.copiedBuffer("hello 客户端",CharsetUtil.UTF_8));
    }
    //处理异常 一般是需要关闭通道
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
}

客户端：

client
package com.tech.netty.netty;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
/**
 * @author lw
 * @since 2021/8/11
 **/
public class NettyClient {
    public static void main(String[] args) throws InterruptedException {
        //客户端需要一个事件循环组
        NioEventLoopGroup eventExecutors = new NioEventLoopGroup();
        try {
            // 创建客户端启动对象 并配置参数
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventExecutors)  //设置线程组
                    .channel(NioSocketChannel.class)  //设置客户端通道
                    .handler(new ChannelInitializer<SocketChannel>() {  //设置处理器
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            socketChannel.pipeline().addLast(new NettyClientHandler());
                        }
                    });
            System.out.println("...客户端 is ready...");
            //连接服务器
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 6668).sync();
            //对通道关闭事件进行监听
            channelFuture.channel().closeFuture().sync();
        } finally {
            eventExecutors.shutdownGracefully();
        }
    }
}
ClientHandler
package com.tech.netty.netty;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
/**
 * @author lw
 * @since 2021/8/11
 **/
public class NettyClientHandler extends ChannelInboundHandlerAdapter {
    //当通道就绪会触发该方法 给服务器发送数据
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("client ctx:"+ctx);
        ctx.writeAndFlush(Unpooled.copiedBuffer("hello 服务器", CharsetUtil.UTF_8));
    }
    //当通道有读取事件时触发
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        ByteBuf byteBuf = (ByteBuf) msg;
        System.out.println("服务器回复的消息："+byteBuf.toString(CharsetUtil.UTF_8));
        System.out.println("服务器的地址："+ctx.channel().remoteAddress());
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        ctx.close();
    }
}