netty实现心跳检测

            <dependency>
                <groupId>io.netty</groupId>
                <artifactId>netty-all</artifactId>
                <version>4.1.20.Final</version>
            </dependency>

package com.example.demo.controller.http;

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.ServerSocketChannel;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.timeout.IdleStateHandler;

import java.util.concurrent.TimeUnit;

//服务端
public class MyServer {

    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup boss=new NioEventLoopGroup();
        EventLoopGroup worker=new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap=new ServerBootstrap();
            bootstrap.group(boss,worker)
                    .channel(NioServerSocketChannel.class)
                    //对boss进行记录处理程序
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            ChannelPipeline pipeline = socketChannel.pipeline();
                            // long readerIdleTime, 表示多长时间没有读 就发送一个心跳包检测是否连接
                            // long writerIdleTime, 表示多长时间没有写 就发送一个心跳包检测是否连接
                            // long allIdleTime 表示多长时间没有读写 就发送一个心跳包检测是否连接
                            pipeline.addLast(new IdleStateHandler(3,5,7, TimeUnit.SECONDS));
                            //当IdleStateEvent 触发后 就会传递给管道的一个处理程序去处理, userEventTiggered 在该方法中去处理
                            pipeline.addLast(new MyHandler());
                        }
                    });
            //绑定端口
            ChannelFuture sync = bootstrap.bind(7777).sync();
            //监听关闭
            sync.channel().closeFuture().sync();
        }finally {
            //优雅关闭
            boss.shutdownGracefully();
            worker.shutdownGracefully();
        }
    }
}

package com.example.demo.controller.http;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleStateEvent;

//服务端业务处理程序
public class MyHandler extends ChannelInboundHandlerAdapter {


    //用户事件触发
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if(evt instanceof IdleStateEvent){
            //向下转型
            IdleStateEvent idleStateEvent=(IdleStateEvent) evt;
            String msg="";
            switch (idleStateEvent.state()){
                case READER_IDLE:
                    msg="读空闲";
                    break;
                case WRITER_IDLE:
                    msg="写空闲";
                    break;
                case ALL_IDLE:
                    msg="读写空闲";
                    break;
            }
            System.out.println(ctx.channel().remoteAddress()+"---超时时间---"+msg);
            System.out.println("服务器做自己的业务处理");
            //关闭通道 就不会在进行心跳检测
           // ctx.channel().close();
        }
    }
}

 telnet 127.0.0.1 7777