基于netty的心跳检测

实现的功能： 

1.客户端网络空闲5秒没有进行写操作是，进行发送一次ping心跳给服务端；

2.客户端如果在下一个发送ping心跳周期来临时，还没有收到服务端pong的心跳应答，则失败心跳计数器加1；

3.每当客户端收到服务端的pong心跳应答后，失败心跳计数器清零；

4.如果连续超过3次没有收到服务端的心跳回复，则断开当前连接，在5秒后进行重连操作，直到重连成功，否则每隔5秒又会进行重连；

5.服务端网络空闲状态到达6秒后，服务端心跳失败计数器加1；

6.只要收到客户端的ping消息，服务端心跳失败计数器清零；

7.服务端连续3次没有收到客户端的ping消息后，将关闭链路，释放资源，等待客户端重连；

服务端代码： 

package com.kg.netty.server;import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelPipeline;import io.netty.channel.EventLoopGroup;import io.netty.channel.SimpleChannelInboundHandler;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.handler.codec.serialization.ClassResolvers;import io.netty.handler.codec.serialization.ObjectDecoder;import io.netty.handler.codec.serialization.ObjectEncoder;import io.netty.handler.timeout.IdleState;import io.netty.handler.timeout.IdleStateEvent;import io.netty.handler.timeout.IdleStateHandler;import java.util.concurrent.TimeUnit;import com.kg.netty.msg.KeepAliveMessage;import com.kg.utils.Constants;import com.kg.utils.Utils;public class KeepAliveServer {// 端口private int port ;public KeepAliveServer(int port) {this.port = port;}ChannelFuture f ;ServerBootstrap b ;// 设置6秒检测chanel是否接受过心跳数据private static final int READ_WAIT_SECONDS = 6;// 定义客户端没有收到服务端的pong消息的最大次数private static final int MAX_UN_REC_PING_TIMES = 3;public void startServer() {EventLoopGroup bossGroup = new NioEventLoopGroup();EventLoopGroup workerGroup = new NioEventLoopGroup();try {b = new ServerBootstrap();b.group(bossGroup, workerGroup);b.channel(NioServerSocketChannel.class);b.childHandler(new KeepAliveServerInitializer());// 服务器绑定端口监听f = b.bind(port).sync();// 监听服务器关闭监听，此方法会阻塞f.channel().closeFuture().sync();// 可以简写为/* b.bind(portNumber).sync().channel().closeFuture().sync(); */} catch (InterruptedException e) {e.printStackTrace();} finally {bossGroup.shutdownGracefully();workerGroup.shutdownGracefully();}}/** * 消息处理器 * @author cullen edward */private class KeepAliveServerInitializer extends ChannelInitializer<SocketChannel> {@Overrideprotected void initChannel(SocketChannel ch) throws Exception {ChannelPipeline pipeline = ch.pipeline();/* * 使用ObjectDecoder和ObjectEncoder * 因为双向都有写数据和读数据，所以这里需要两个都设置 * 如果只读，那么只需要ObjectDecoder即可 */pipeline.addLast("decoder", new ObjectDecoder(ClassResolvers.cacheDisabled(this.getClass().getClassLoader())));pipeline.addLast("encoder", new ObjectEncoder());/* * 这里只监听读操作 * 可以根据需求，监听写操作和总得操作 */pipeline.addLast("pong", new IdleStateHandler(READ_WAIT_SECONDS, 0, 0,TimeUnit.SECONDS));pipeline.addLast("handler", new Heartbeat());}}private class Heartbeat extends SimpleChannelInboundHandler<KeepAliveMessage> { // 失败计数器：未收到client端发送的ping请求private int unRecPingTimes = 0 ;// 每个chanel对应一个线程，此处用来存储对应于每个线程的一些基础数据，此处不一定要为KeepAliveMessage对象ThreadLocal<KeepAliveMessage> localMsgInfo = new ThreadLocal<KeepAliveMessage>(); @Overrideprotected void channelRead0(ChannelHandlerContext ctx, KeepAliveMessage msg) throws Exception {System.out.println(ctx.channel().remoteAddress() + " Say : sn=" + msg.getSn()+",reqcode="+msg.getReqCode());        // 收到ping消息后，回复if(Utils.notEmpty(msg.getSn())&&msg.getReqCode()==1){msg.setReqCode(Constants.RET_CODE);ctx.channel().writeAndFlush(msg);// 失败计数器清零unRecPingTimes = 0;if(localMsgInfo.get()==null){KeepAliveMessage localMsg = new KeepAliveMessage();localMsg.setSn(msg.getSn());localMsgInfo.set(localMsg);/* * 这里可以将设备号放入一个集合中进行统一管理 */// TODO}}else{ctx.channel().close();}}public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {        if (evt instanceof IdleStateEvent) {            IdleStateEvent event = (IdleStateEvent) evt;            if (event.state() == IdleState.READER_IDLE) {                /*读超时*/                System.out.println("===服务端===(READER_IDLE 读超时)");                // 失败计数器次数大于等于3次的时候，关闭链接，等待client重连                if(unRecPingTimes >= MAX_UN_REC_PING_TIMES){                System.out.println("===服务端===(读超时，关闭chanel)");                // 连续超过N次未收到client的ping消息，那么关闭该通道，等待client重连                ctx.channel().close();                }else{                // 失败计数器加1                unRecPingTimes++;                }            } else if (event.state() == IdleState.WRITER_IDLE) {                /*写超时*/                   System.out.println("===服务端===(WRITER_IDLE 写超时)");            } else if (event.state() == IdleState.ALL_IDLE) {                /*总超时*/                System.out.println("===服务端===(ALL_IDLE 总超时)");            }        }    }    @Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {    System.out.println("错误原因："+cause.getMessage());    if(localMsgInfo.get()!=null){/* * 从管理集合中移除设备号等唯一标示，标示设备离线 */    // TODO    }    ctx.channel().close();}@Override    public void channelActive(ChannelHandlerContext ctx) throws Exception {        System.out.println("Client active ");        super.channelActive(ctx);    }@Overridepublic void channelInactive(ChannelHandlerContext ctx) throws Exception {// 关闭，等待重连    ctx.close();if(localMsgInfo.get()!=null){/* * 从管理集合中移除设备号等唯一标示，标示设备离线 */    // TODO    }    System.out.println("===服务端===(客户端失效)");}}public void stopServer(){if(f!=null){f.channel().close();}}/** * @param args */public static void main(String[] args) {KeepAliveServer keepAliveServer = new KeepAliveServer(1666);keepAliveServer.startServer();}}

客户端代码：

package com.kg.netty.client;import io.netty.bootstrap.Bootstrap;import io.netty.channel.Channel;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelPipeline;import io.netty.channel.EventLoopGroup;import io.netty.channel.SimpleChannelInboundHandler;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioSocketChannel;import io.netty.handler.codec.serialization.ClassResolvers;import io.netty.handler.codec.serialization.ObjectDecoder;import io.netty.handler.codec.serialization.ObjectEncoder;import io.netty.handler.timeout.IdleState;import io.netty.handler.timeout.IdleStateEvent;import io.netty.handler.timeout.IdleStateHandler;import java.util.concurrent.Executors;import java.util.concurrent.ScheduledExecutorService;import java.util.concurrent.TimeUnit;import com.kg.netty.msg.KeepAliveMessage;import com.kg.utils.Constants;public class KeepAliveClient {private String host ;private int port ;private EventLoopGroup group ;private Bootstrap b ;private Channel ch ;// 定义客户端没有收到服务端的pong消息的最大次数private static final int MAX_UN_REC_PONG_TIMES = 3;// 多长时间未请求后，发送心跳private static final int WRITE_WAIT_SECONDS = 5;// 隔N秒后重连private static final int RE_CONN_WAIT_SECONDS = 5;// 客户端连续N次没有收到服务端的pong消息  计数器private int unRecPongTimes = 0 ;private ScheduledExecutorService executorService ;// 是否停止private boolean isStop = false ;public KeepAliveClient(String host, int port) {this.host = host ;this.port = port ;group = new NioEventLoopGroup();b = new Bootstrap();b.group(group).channel(NioSocketChannel.class).handler(new HeartbeatInitializer());}public void start() {connServer();}private void connServer(){isStop = false;if(executorService!=null){executorService.shutdown();}executorService = Executors.newScheduledThreadPool(1);executorService.scheduleWithFixedDelay(new Runnable() {boolean isConnSucc = true;@Overridepublic void run() {try {// 重置计数器unRecPongTimes = 0;// 连接服务端if(ch!=null&&ch.isOpen()){ch.close();}ch = b.connect(host, port).sync().channel();// 此方法会阻塞//ch.closeFuture().sync();System.out.println("connect server finish");} catch (Exception e) {e.printStackTrace();isConnSucc = false ;} finally{if(isConnSucc){if(executorService!=null){executorService.shutdown();}}}}}, RE_CONN_WAIT_SECONDS, RE_CONN_WAIT_SECONDS, TimeUnit.SECONDS);}public class HeartbeatInitializer extends ChannelInitializer<SocketChannel> {     @Override    protected void initChannel(SocketChannel ch) throws Exception {        ChannelPipeline pipeline = ch.pipeline(); pipeline.addLast("decoder", new ObjectDecoder(ClassResolvers.cacheDisabled(this.getClass().getClassLoader())));        pipeline.addLast("encoder", new ObjectEncoder());         pipeline.addLast("ping", new IdleStateHandler(0, WRITE_WAIT_SECONDS, 0,TimeUnit.SECONDS));        // 客户端的逻辑        pipeline.addLast("handler", new ClientHandler());    }}public class ClientHandler extends SimpleChannelInboundHandler<KeepAliveMessage> {     @Override    protected void channelRead0(ChannelHandlerContext ctx, KeepAliveMessage msg)            throws Exception {    System.out.println("Server say : sn=" + msg.getSn()+",reqcode="+msg.getReqCode());        if (Constants.RET_CODE == msg.getReqCode()) {        // 计数器清零        unRecPongTimes = 0;        }    }        @Override    public void channelActive(ChannelHandlerContext ctx) throws Exception {        System.out.println("Client active ");        super.channelActive(ctx);    }    @Override    public void channelInactive(ChannelHandlerContext ctx) throws Exception {        System.out.println("Client close ");        super.channelInactive(ctx);        /*         * 重连         */        if(!isStop){        connServer();        }    }        public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {        if (evt instanceof IdleStateEvent) {            IdleStateEvent event = (IdleStateEvent) evt;            if (event.state() == IdleState.READER_IDLE) {                /*读超时*/                System.out.println("===服务端===(READER_IDLE 读超时)");            } else if (event.state() == IdleState.WRITER_IDLE) {                /*写超时*/                   System.out.println("===服务端===(WRITER_IDLE 写超时)");                if(unRecPongTimes < MAX_UN_REC_PONG_TIMES){                ctx.channel().writeAndFlush(getSrcMsg()) ;                unRecPongTimes++;                }else{                ctx.channel().close();                }            } else if (event.state() == IdleState.ALL_IDLE) {                /*总超时*/                System.out.println("===服务端===(ALL_IDLE 总超时)");            }        }    }}private KeepAliveMessage getSrcMsg(){KeepAliveMessage keepAliveMessage = new KeepAliveMessage();// 设备码        keepAliveMessage.setSn("sn_123456abcdfef");        keepAliveMessage.setReqCode(Constants.REQ_CODE);        return keepAliveMessage ;}public void stop(){isStop = true;if(ch!=null&&ch.isOpen()){ch.close();}if(executorService!=null){executorService.shutdown();}}/** * @param args */public static void main(String[] args) {KeepAliveClient keepAliveServer = new KeepAliveClient("127.0.0.1",1666);keepAliveServer.start();}}

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摘抄自：http://www.aichengxu.com/view/46626

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