Programa de entrada Netty: ingresa datos desde la consola y los envía al servidor, y el servidor los devuelve al cliente tal como están.

Vaya directamente al código:

dependencias de pom:

        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.42.Final</version>
        </dependency>

Servidor:

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
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.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

public class NettyServer {
    public static void main(String[] args) throws InterruptedException {
        // 创建两个线程组，bossGroup只处理连接请求，workerGroup处理具体的业务
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap bootstrap = new ServerBootstrap();
            bootstrap.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            //按行解码
                            pipeline.addLast(new LineBasedFrameDecoder(1024));
                            //将LineBasedFrameDecoder解码出来的数据字解码为字符串
                            pipeline.addLast(new StringDecoder());
                            //用于将发送的数据编码
                            pipeline.addLast(new StringEncoder());
                            pipeline.addLast(new SimpleServerHandler());
                        }
                    });

            // 绑定端口，开始接收进来的连接
            ChannelFuture future = bootstrap.bind(8080).sync();
            System.out.println("Server start listen at 8080 ");
            future.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

import java.nio.charset.StandardCharsets;

public class SimpleServerHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println("client msg:" + msg);
        byte[] bytes = (msg + "\r\n").getBytes(StandardCharsets.UTF_8);
        ctx.channel().writeAndFlush(Unpooled.wrappedBuffer(bytes)).sync();
    }
}

Cliente:

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
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.NioSocketChannel;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;


public class NettyClient {

    public static void main(String[] args) throws Exception {
        // 创建事件循环组
        EventLoopGroup group = new NioEventLoopGroup();

        try {
            // 创建Bootstrap对象
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(group)
                    .channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .option(ChannelOption.SO_KEEPALIVE, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new CustomChannelHandler());
                        }
                    });

            // 连接服务器
            ChannelFuture future = bootstrap.connect("localhost", 8080).sync();
            System.out.println("Connected to server");

            // 从控制台读取输入，并发送给服务器
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            while (true) {
                String line = reader.readLine();
                if (line == null) {
                    break;
                }
                // 发送一行数据，并加上回车换行符
                // 将String类型的消息转换为ByteBuf类型的消息
                byte[] bytes = (line + "\r\n").getBytes(StandardCharsets.UTF_8);
                future.channel().writeAndFlush(Unpooled.wrappedBuffer(bytes)).sync();
            }
            // 等待连接关闭
            future.channel().closeFuture().sync();
        } finally {
            // 优雅地关闭事件循环组
            group.shutdownGracefully();
        }
    }
}

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.nio.charset.StandardCharsets;

public class CustomChannelHandler extends ChannelInboundHandlerAdapter {
    // 处理接收到的消息
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        // 处理接收到的消息
        String line = ((ByteBuf) msg).toString(StandardCharsets.UTF_8);
        System.out.println("Received message: " + line);
    }
}