高并发网络编程Netty的第一个案例 - 超级大汇总——DBC的博客超级大汇总—

一、什么是Echo服务和快速创建Netty项目

什么是Echo服务：就是一个应答服务（回显服务器），客户端发送什么数据，服务端就响应的对应的数据，是一个用于调试和检测的服务
IDEA + Maven + jdk8 netty依赖包
Maven地址：点我前往

也可以用我的版本，我的版本是2022年7月

<!-- https://mvnrepository.com/artifact/io.netty/netty-all -->
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-all</artifactId>
    <version>4.1.79.Final</version>
</dependency>

二、Netty实战之Echo服务-服务端程序编写实战

EchoServer

package com.example.test05.demo.echo;

import io.netty.bootstrap.ServerBootstrap;
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;

public class EchoServer {

    private int port;

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

    /**
     * 启动流程
     */
    public void run() throws InterruptedException {

        //配置服务端线程组  两个线程组
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new EchoServerHandler());
                        }
                    });

            System.out.println("Echo 服务器启动ing");

            //绑定端口，同步等待成功
            ChannelFuture channelFuture = serverBootstrap.bind(port).sync();

            //等待服务端监听端口关闭
            channelFuture.channel().closeFuture().sync();
        } finally {

            //优雅退出，释放线程池
            workGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }


    }


    public static void main(String[] args) throws InterruptedException {
        int port = 8080;
        if (args.length > 0) {
            port = Integer.parseInt(args[0]);
        }

        new EchoServer(port).run();

    }

}

EchoServerHandler

package com.example.test05.demo.echo;

import io.netty.buffer.ByteBuf;
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 data = (ByteBuf) msg;

        System.out.println("服务端收到数据: "+ data.toString(CharsetUtil.UTF_8));

        ctx.writeAndFlush(data);
    }


    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

        System.out.println("EchoServerHandle channelReadComplete");
    }

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

}

三、Netty实战之Echo服务-客户端程序编写实战

EchoClient

package com.example.test05.demo.echo;

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.NioSocketChannel;

import java.net.InetSocketAddress;

public class EchoClient {

    private String host;

    private 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 bootstrap = new Bootstrap();
            bootstrap.group(group)

                    .channel(NioSocketChannel.class)

                    .remoteAddress(new InetSocketAddress(host, port))

                    .handler(new ChannelInitializer<SocketChannel>() {

                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new EchoClientHandler());
                        }
                    });

            //连接到服务端，connect是异步连接，在调用同步等待sync，等待连接成功
            ChannelFuture channelFuture = bootstrap.connect().sync();

            //阻塞直到客户端通道关闭
            channelFuture.channel().closeFuture().sync();

        } finally {
            //优雅退出，释放NIO线程组
            group.shutdownGracefully();
        }

    }

    public static void main(String[] args) throws InterruptedException {
        new EchoClient("127.0.0.1", 8081).start();
    }

}

EchoClientHandler

package com.example.test05.demo.echo;

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> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {

        System.out.println("Client received: " + msg.toString(CharsetUtil.UTF_8));

    }


    /**
     * 激活之后运行
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("Active");
        // 申请一个内存 Unpooled.copiedBuffer
        ctx.writeAndFlush(Unpooled.copiedBuffer("DBC博客 www.dbc655.top",CharsetUtil.UTF_8));
    }


    /**
     * 读取数据结束后
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        System.out.println("EchoClientHandler channelReadComplete");
    }


    /**
     * 异常捕获的方法
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

温馨提示

输出结果为：