netty的心跳检测与断线重连_new idlestatehandler(10,0,0, timeunit.seconds)

作者：weixin_40725706 | 2024-03-15 15:10:15

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new idlestatehandler(10,0,0, timeunit.seconds)

服务端代码

NettyServer


package com.example.netty.netty2;
 
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import lombok.extern.slf4j.Slf4j;
 
@Slf4j
public class NettyServer {
 
    private NettyServerChannelInitializer serverChannelInitializer = null;
 
    private int port = 8888;
 
 
    public void bind() throws Exception {
        //配置服务端的NIO线程组
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            serverChannelInitializer = new NettyServerChannelInitializer();
            ServerBootstrap b = new ServerBootstrap();
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    //保持长连接
                    .childOption(ChannelOption.SO_KEEPALIVE,true)
                    .option(ChannelOption.SO_BACKLOG, 1024)
                    .childHandler(serverChannelInitializer);
 
            //绑定端口，同步等待成功
            ChannelFuture f = b.bind(port).sync();
 
 
            //等待服务器监听端口关闭
            f.channel().closeFuture().sync();
        } finally {
            //释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
 
    public static void main(String[] args) throws Exception {
        new  NettyServer().bind();
    }
 
}

自定义channel类里面涉及有拆包，粘包，编解码以及其他自定义操作(心跳检测)


package com.example.netty.netty2;
 
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import java.util.concurrent.TimeUnit;
 
 
public class NettyServerChannelInitializer extends ChannelInitializer<SocketChannel> {
 
    private NettyServerHandler handler ;
 
 
 
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //解决TCP粘包拆包的问题，以特定的字符结尾（$_）
        pipeline.addLast(new DelimiterBasedFrameDecoder(Integer.MAX_VALUE, Unpooled.copiedBuffer("$_".getBytes())));
        //字符串解码和编码
        pipeline.addLast("decoder", new StringDecoder());
        pipeline.addLast("encoder", new StringEncoder());
        pipeline.addLast(new IdleStateHandler(3,0,0,TimeUnit.SECONDS));
        //服务器的逻辑
        handler = new NettyServerHandler();
        pipeline.addLast("handler", handler);
    }
}

NettyServerHandler 心跳检测


package com.example.netty.netty2;
 
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
import lombok.extern.slf4j.Slf4j;
 
 
@Slf4j
public class NettyServerHandler extends SimpleChannelInboundHandler {
 
    /**
     * 心跳丢失次数
     */
    private int counter = 0;
 
 
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Client say : " + msg.toString());
        //重置心跳丢失次数
        counter = 0;
    }
 
 
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        log.info("服务端被 : " + ctx.channel().remoteAddress().toString()+ " 连接上了 !");
        super.channelActive(ctx);
    }
 
 
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            if (event.state().equals(IdleState.READER_IDLE)){
                // 空闲40s之后触发 (心跳包丢失)
                if (counter >= 3) {
                    // 连续丢失3个心跳包 (断开连接)
                    ctx.channel().close().sync();
                    log.error("已与"+ctx.channel().remoteAddress()+"断开连接");
                    System.out.println("已与"+ctx.channel().remoteAddress()+"断开连接");
                } else {
                    counter++;
                    log.debug(ctx.channel().remoteAddress() + "丢失了第 "+ctx.channel().remoteAddress() + counter + " 个心跳包");
                    System.out.println("丢失了"+ctx.channel().remoteAddress()+"第 " + counter + " 个心跳包");
                }
            }
 
        }
    }
}

客户端

NettyClient


package com.example.netty.netty2;
 
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoop;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import java.util.concurrent.TimeUnit;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
 
@Slf4j
public class NettyClient {
 
    private String host;
 
    private int port;
 
    private static Channel channel;
 
    public NettyClient(){
 
    }
 
    public NettyClient(String host, int port) {
        this.host = host;
        this.port = port;
    }
 
 
 
    public void start()  {
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .option(ChannelOption.SO_KEEPALIVE,true)
                    .channel(NioSocketChannel.class)
                    .handler(new ClientChannelInitializer(host,port));
 
            ChannelFuture f = b.connect(host,port);
 
//            //断线重连
            f.addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture channelFuture) throws Exception {
                    if (!channelFuture.isSuccess()) {
                        final EventLoop loop = channelFuture.channel().eventLoop();
                        loop.schedule(new Runnable() {
                            @Override
                            public void run() {
                                log.error("服务端链接不上，开始重连操作...");
                                System.err.println("服务端链接不上，开始重连操作...");
                                start();
                            }
                        }, 1L, TimeUnit.SECONDS);
                    } else {
                        channel = channelFuture.channel();
                        log.info("服务端链接成功...");
                        System.err.println("服务端链接成功...");
                    }
                }
            });
 
        }catch (Exception e){
            e.printStackTrace();
        }
    }
 
    public static void main(String[] args) {
        new NettyClient ("127.0.0.1",8888).start();
    }
}

ClientChannelInitializer


package com.example.netty.netty2;
 
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.handler.timeout.IdleStateHandler;
import java.util.concurrent.TimeUnit;
 
public class ClientChannelInitializer extends ChannelInitializer<SocketChannel> {
 
    private String host;
    private int port;
 
    public ClientChannelInitializer( String host, int port) {
        this.host = host;
        this.port = port;
    }
 
    @Override
    protected void initChannel(SocketChannel socketChannel) throws Exception {
        ChannelPipeline pipeline = socketChannel.pipeline();
        //解决TCP粘包拆包的问题，以特定的字符结尾（$_）
        pipeline.addLast(new DelimiterBasedFrameDecoder(Integer.MAX_VALUE, Unpooled.copiedBuffer("$_".getBytes())));
        //字符串解码和编码
        pipeline.addLast("decoder", new StringDecoder());
        pipeline.addLast("encoder", new StringEncoder());
        //心跳检测
        pipeline.addLast(new IdleStateHandler(0,10,0,TimeUnit.SECONDS));
        //客户端的逻辑
        pipeline.addLast("handler", new NettyClientHandler(host,port));
 
    }
}

NettyClientHandler


package com.example.netty.netty2;
 
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.EventLoop;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
import java.util.concurrent.TimeUnit;
import lombok.extern.slf4j.Slf4j;
 
@Slf4j
public class NettyClientHandler extends SimpleChannelInboundHandler {
 
    private String host;
    private int port;
    private NettyClient nettyClinet;
    private String tenantId;
 
 
    public NettyClientHandler(String host, int port) {
        this.host = host;
        this.port = port;
        nettyClinet = new NettyClient(host,port);
    }
 
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, Object o)
            throws Exception {
        System.out.println("Server say : " + o.toString());
    }
 
 
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("通道已连接！！");
    }
 
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("断线了。。。。。。");
        //使用过程中断线重连
        final EventLoop eventLoop = ctx.channel().eventLoop();
        eventLoop.schedule(new Runnable() {
            @Override
            public void run() {
                nettyClinet.start();
            }
        }, 1, TimeUnit.SECONDS);
 
        ctx.fireChannelInactive();
    }
 
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt)
            throws Exception {
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            if (event.state().equals(IdleState.READER_IDLE)) {
                System.out.println("READER_IDLE");
 
            } else if (event.state().equals(IdleState.WRITER_IDLE)) {
                /**发送心跳,保持长连接*/
                String  s = "ping$_";
                ctx.channel().writeAndFlush(s);
                log.debug("心跳发送成功!");
                System.out.println("心跳发送成功!");
            } else if (event.state().equals(IdleState.ALL_IDLE)) {
                System.out.println("ALL_IDLE");
            }
        }
        super.userEventTriggered(ctx, evt);
    }
 
}

心跳检测类里面关键代码IdleStateHandler

readerIdleTime：为读超时时间（即测试端一定时间内未接受到被测试端消息）
writerIdleTime：为写超时时间（即测试端一定时间内向被测试端发送消息）
allIdleTime：所有类型的超时时间
比如在这里，服务端每隔3S检测一下，若超过3次，就自动断开连接，
客户端是每个10S中发送一个心跳包到服务端。
so,如非异常情况，会一直保持通信，因为服务端在将要端口连接的时候，这个时候客户端发送了一个心跳包。

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