基于netty的心跳检测，有需要的朋友可以参考下。
这两天由于要给android系统的设备写一个心跳功能，所以在这里写一个基于netty的心跳检测功能。
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> {
@Override
protected 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>();
@Override
protected 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)");
}
}
}
@Override
public 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);
}
@Override
public 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;
@Override
public 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();
}
}
参考网站：
http://coder.beitown.com/archives/1180
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http://download.csdn.net/detail/asd13141718/8492741