Netty入门实例 TCP服务

Bertha 。 2022-09-04 05:54 132阅读 0赞

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();
        }
    }