Netty保姆级入门教程

今天是实战篇，没有理论，只是记录一下使用Netty搭建一个本地服务，实现客户端数据发送到服务端数据Demo的教程，理论篇以及更深层次学习Netty可以点个关注，保证后续更新不错过！！！

搭建Netty服务端

服务端

使用main方法的形式构建，启动在本地8888端口

package com.zuiyu.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.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * @author @醉鱼
 * @link https://github.com/TianPuJun
 * @ClassName NettyService
 * @Description
 * @Date 22:05 2022/6/28
 **/
public class NettyService {
    public static void main(String[] args) throws InterruptedException {
        // 用于接收客户端链接的线程工作组
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        // 用于接收客户端链接读写操作的线程组
        EventLoopGroup workGroup = new NioEventLoopGroup();
        // 辅助类，帮助创建netty服务
        ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap
                // 绑定两个工作组
                .group(eventLoopGroup,workGroup)
                // 设置nio 模式
                .channel(NioServerSocketChannel.class)
                // option 针对服务器端配置，childOption 针对客户端链接通道配置
                // 设置tcp 缓冲区
                .option(ChannelOption.SO_BACKLOG,1024)
                // 设置发送数据的缓存大小
                .childOption(ChannelOption.SO_SNDBUF,32*1024)
                // 设置读取数据的缓存大小
                .childOption(ChannelOption.SO_RCVBUF,32*1024)
                // 设置保持长链接
                .childOption(ChannelOption.SO_KEEPALIVE,true)
                // 初始化绑定服务通道
                .childHandler(new ChannelInitializer() {
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        // 为通道进行初始化，数据传输过来的适合会进行拦截和执行(可以有多个拦截器)
                        socketChannel.pipeline().addLast(new ServerHandler());
                    }
                });
        ChannelFuture sync = serverBootstrap.bind(8888).sync();
        // 释放链接
        sync.channel().closeFuture().sync();
        workGroup.shutdownGracefully();
        eventLoopGroup.shutdownGracefully();
    }
}

服务端监听

新建ServerHandler监听数据

package com.zuiyu.netty;

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

import java.util.logging.Logger;

/**
 * @author @醉鱼
 * @link https://github.com/TianPuJun
 * @ClassName ServerHandler
 * @Description 服务回调
 * @Date 22:15 2022/6/28
 **/
public class ServerHandler extends ChannelInboundHandlerAdapter {
    public static final Logger LOGGER = Logger.getLogger("ServerHandler");
    public ServerHandler() {
        super();
    }

    @Override
    public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
        super.channelRegistered(ctx);
    }

    @Override
    public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
        super.channelUnregistered(ctx);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        LOGGER.info("======服务端通道激活======");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        super.channelInactive(ctx);
    }

    /**
     * 当通道有数据读取时的监听
     * @param ctx
     * @param msg
     * @throws Exception
     */
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
            // 传输buffer 对象
            ByteBuf buf = (ByteBuf)msg;
            // 定义byte数组
            byte[] req =new byte[buf.readableBytes()];
            // 从缓冲区获取数据到req
            buf.readBytes(req);
            // 读取数据转为字符串
            String body = new String(req,"utf-8");
            LOGGER.info("服务端读取的数据："+body);
            // 响应给客户端的数据
            ctx.writeAndFlush(Unpooled.copiedBuffer("netty server response data: you are beautiful".getBytes()))
            // 添加addListener可以触发关闭通道监听事件，客户端短链接场景使用
            // .addListener(ChannelFutureListener.CLOSE);
            ;

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            ReferenceCountUtil.release(msg);
        }
    }

    /**
     * 当我们读取完成数据时触发的操作
     * @param ctx
     * @throws Exception
     */
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        LOGGER.info("====== 服务端数据读取完成 ======");
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        super.userEventTriggered(ctx, evt);
    }

    @Override
    public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
        super.channelWritabilityChanged(ctx);
    }

    /**
     * 当我们读取数据异常的时候触发的监听
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        LOGGER.info("====== 服务端数据读取异常 ======");
        LOGGER.info(cause.getMessage());
        ctx.close();
    }
}

搭建Netty客户端

客户端

同样适用main方法的形式搭建测试，发送数据到本地8888端口

package com.zuiyu.netty;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
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 @醉鱼
 * @link https://github.com/TianPuJun
 * @ClassName NettyClient
 * @Description
 * @Date 22:27 2022/6/28
 **/
public class NettyClient {
    public static void main(String[] args) throws InterruptedException {
        NioEventLoopGroup eventExecutors = new NioEventLoopGroup();
        Bootstrap b = new Bootstrap();
        b.group(eventExecutors)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer() {
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new ClientHandler());
                    }
                });
        ChannelFuture channelFuture = b.connect("127.0.0.1", 8888).syncUninterruptibly();
        channelFuture.channel().writeAndFlush(Unpooled.copiedBuffer("netty 客户端请求数据:zuiyu netty 服务发送数据测试".getBytes()));
        // 释放链接
        channelFuture.channel().closeFuture().sync();
    }
}

客户端监听

新建客户端监听ClientHandler，发送数据时打印数据

package com.zuiyu.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.ReferenceCountUtil;

import java.util.logging.Logger;

/**
 * @author @醉鱼
 * @link https://github.com/TianPuJun
 * @ClassName ClientHandler
 * @Description
 * @Date 22:32 2022/6/28
 **/
public class ClientHandler extends ChannelInboundHandlerAdapter {
    public static final Logger LOGGER = Logger.getLogger("ClientHandler");

    public ClientHandler() {
        super();
    }

    @Override
    public void channelRegistered(ChannelHandlerContext ctx) throws Exception {
        super.channelRegistered(ctx);
    }

    @Override
    public void channelUnregistered(ChannelHandlerContext ctx) throws Exception {
        super.channelUnregistered(ctx);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        LOGGER.info("====== 客户端通道激活======");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        super.channelInactive(ctx);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
            // 传输buffer 对象
            ByteBuf buf = (ByteBuf)msg;
            // 定义byte数组
            byte[] req =new byte[buf.readableBytes()];
            // 从缓冲区获取数据到req
            buf.readBytes(req);
            // 读取数据转为字符串
            String body = new String(req,"utf-8");
            LOGGER.info("客户端读取的数据："+body);

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            ReferenceCountUtil.release(msg);
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        LOGGER.info("====== 客户端读取数据完毕======");
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        super.userEventTriggered(ctx, evt);
    }

    @Override
    public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
        super.channelWritabilityChanged(ctx);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        LOGGER.info("====== 客户端读取数据异常======");
        ctx.close();
    }
}

验证打印输出

• 先启动NettyServer#main
• 再启动NettyClient#main
• 结果如下

Demo 教程到此结束，只为记录过程，代码详细位置NettyServer中都有注释，觉得有帮助动动小手点个关注再走哦，点关注不迷路

Demo 地址 :

https://github.com/TianPuJun/spring-notes/tree/master/netty

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