第三阶段，JavaEE高级框架：Netty实践（四）—— 心跳检测实现

标签：netty 心跳检测

心跳检测的概念

在分布式架构中，比如Hadoop集群，Storm集群等，或多或少都涉及到Master/Slave的概念，往往是一个或者多个Master和N个Slave之间进行通信。那么通常Master应该需要知道Slave的状态，Slave会定时的向Master进行发送消息，相当于告知Master：“我还活着，我现在在做什么，什么进度，我的CPU/内存情况如何”等，这就是所谓的心跳。Master根据Slave的心跳，进行协调，比如Slave的CPU/内存消耗很大，那么Master可以将任务分配给其他负载小的Slave进行处理；比如Slave一段时间没有发送心跳过来，那么Master可能会将可服务列表中暂时删除该Slave，并可能发出报警，告知运维/开发人员进行处理.

Netty实现心跳检测代码实例

心跳信息对象

主要储存Slave的IP,通信PORT，时间，内存，CPU信息等。

package day4;

import java.io.Serializable;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**

Created by zhangfengzhe on 2017/2/4.
*/
public class HeartInfo implements Serializable{

private String ip;

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private int port;

private Date lasttime;

private Map<String , String> cpuInfo = new HashMap<String,String>();

private Map<String , String> memInfo = new HashMap<String, String>();

public String getIp() {
return ip;
}

public void setIp(String ip) {
this.ip = ip;
}

public int getPort() {
return port;
}

public void setPort(int port) {
this.port = port;
}

public Date getLasttime() {
return lasttime;
}

public void setLasttime(Date lasttime) {
this.lasttime = lasttime;
}

public Map<String, String> getCpuInfo() {
return cpuInfo;
}

public void setCpuInfo(Map<String, String> cpuInfo) {
this.cpuInfo = cpuInfo;
}

public Map<String, String> getMemInfo() {
return memInfo;
}

public void setMemInfo(Map<String, String> memInfo) {
this.memInfo = memInfo;
}

@Override
public String toString() {
return “HeartInfo{” +
“ip=‘” + ip + ‘\‘‘ +
“, port=” + port +
“, lasttime=” + lasttime +
“, cpuInfo=” + cpuInfo +
“, memInfo=” + memInfo +
‘}‘;
}
}

JBoss Marshalling编解码处理器

package day3;

import io.netty.handler.codec.marshalling.DefaultMarshallerProvider;
import io.netty.handler.codec.marshalling.DefaultUnmarshallerProvider;
import io.netty.handler.codec.marshalling.MarshallerProvider;
import io.netty.handler.codec.marshalling.MarshallingDecoder;
import io.netty.handler.codec.marshalling.MarshallingEncoder;
import io.netty.handler.codec.marshalling.UnmarshallerProvider;

import org.jboss.marshalling.MarshallerFactory;
import org.jboss.marshalling.Marshalling;
import org.jboss.marshalling.MarshallingConfiguration;

/**

Marshalling工厂
*/
public final class MarshallingCodeCFactory {

/**
- 创建Jboss Marshalling解码器MarshallingDecoder
- @return MarshallingDecoder
  */
  public static MarshallingDecoder buildMarshallingDecoder() {
  //首先通过Marshalling工具类的精通方法获取Marshalling实例对象参数serial标识创建的是java序列化工厂对象。
  final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory(“serial”);
  //创建了MarshallingConfiguration对象，配置了版本号为5
  final MarshallingConfiguration configuration = new MarshallingConfiguration();
  configuration.setVersion(5);
  //根据marshallerFactory和configuration创建provider
  UnmarshallerProvider provider = new DefaultUnmarshallerProvider(marshallerFactory, configuration);
  //构建Netty的MarshallingDecoder对象，俩个参数分别为provider和单个消息序列化后的最大长度
  MarshallingDecoder decoder = new MarshallingDecoder(provider, 1024);
  return decoder;
  }
/**
- 创建Jboss Marshalling编码器MarshallingEncoder
- @return MarshallingEncoder
  */
  public static MarshallingEncoder buildMarshallingEncoder() {
  final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory(“serial”);
  final MarshallingConfiguration configuration = new MarshallingConfiguration();
  configuration.setVersion(5);
  MarshallerProvider provider = new DefaultMarshallerProvider(marshallerFactory, configuration);
  //构建Netty的MarshallingEncoder对象，MarshallingEncoder用于实现序列化接口的POJO对象序列化为二进制数组
  MarshallingEncoder encoder = new MarshallingEncoder(provider);
  return encoder;
  }
  }

Client

package day4;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

public class Client {

public static void main(String[] args) throws Exception{

  EventLoopGroup group = new NioEventLoopGroup();
  Bootstrap b = new Bootstrap();

  final int port = 8765;
  final String serverIP = "127.0.0.1";

  b.group(group)
   .channel(NioSocketChannel.class)
   .handler(new ChannelInitializer<SocketChannel>() {
     @Override
     protected void initChannel(SocketChannel sc) throws Exception {
        sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
        sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
        sc.pipeline().addLast(new ClientHandler(port));
     }
  });
  
  ChannelFuture cf = b.connect(serverIP, port).sync();

  cf.channel().closeFuture().sync();
  group.shutdownGracefully();

}
}

Client Handler

package day4;

import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**

Created by zhangfengzhe on 2017/2/4.
*/
public class ClientHandler extends ChannelHandlerAdapter {

private String ip;
private int port;
private ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(1);
private ScheduledFuture<?> scheduledFuture;

private static final String SUCCESS = “OK”;

public ClientHandler(){}

public ClientHandler(int port) {
```
 this.port = port;

 //获取本机IP
 try {
     this.ip = InetAddress.getLocalHost().getHostAddress();
 } catch (UnknownHostException e) {
     e.printStackTrace();
 }
```
}

//通道建立初始化时发送信息准备握手验证
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
```
 String authInfo = this.ip + ":" + this.port;

 ctx.writeAndFlush(authInfo);
```
}

//当服务器发送认证信息后,开始启动心跳发送
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
```
 if(msg instanceof String){

     //认证成功
     if(SUCCESS.equals((String)msg)){

         this.scheduledFuture = scheduledExecutorService.scheduleWithFixedDelay(new HeartTask(ctx,ip,port),2,3, TimeUnit.SECONDS);

     }else{

         System.out.println("服务器发来消息：" + msg);
     }

 }

 ReferenceCountUtil.release(msg);
```
}

//如果出现异常取消定时
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
```
 cause.printStackTrace();
 if(this.scheduledFuture != null){
     this.scheduledFuture.cancel(true);
     this.scheduledFuture = null;
 }
```
}
}
Client和Server建立通道初始化的时候，Client会向服务器发送信息用于认证。在实际开发中，Client在发送心跳前，需要和Server端进行握手验证，会涉及到加解密，这里为了简单起见，省去了这些过程。从上面的代码也可以看到，如果服务端认证成功，那么Client会开始启动定时线程去执行任务，那么接下来，我们看看这个心跳任务。

心跳任务HeartTask

package day4;

import io.netty.channel.ChannelHandlerContext;
import org.hyperic.sigar.CpuPerc;
import org.hyperic.sigar.Mem;
import org.hyperic.sigar.Sigar;

import java.util.Date;
import java.util.Random;

/**

Created by zhangfengzhe on 2017/2/4.
*/
public class HeartTask implements Runnable{

//持有引用,方便读写操作
private ChannelHandlerContext ctx;

private HeartInfo heartInfo = new HeartInfo();

public HeartTask(ChannelHandlerContext ctx, String ip, int port) {

 this.ctx = ctx;

 heartInfo.setIp(ip);
 heartInfo.setPort(port);

}

@Override
public void run() {

 try{
     //利用sigar获取 内存/CPU方面的信息 ; 利用CTX给服务器端发送消息
     Sigar sigar = new Sigar();

     //内存使用信息memory
     Mem mem = sigar.getMem();
     heartInfo.getMemInfo().put("total",String.valueOf(mem.getTotal()));
     heartInfo.getMemInfo().put("used",String.valueOf(mem.getUsed()));
     heartInfo.getMemInfo().put("free",String.valueOf(mem.getFree()));


     //CPU使用信息
     CpuPerc cpuPerc = sigar.getCpuPerc();
     heartInfo.getCpuInfo().put("user",String.valueOf(cpuPerc.getUser()));
     heartInfo.getCpuInfo().put("sys",String.valueOf(cpuPerc.getSys()));
     heartInfo.getCpuInfo().put("wait",String.valueOf(cpuPerc.getWait()));
     heartInfo.getCpuInfo().put("idle",String.valueOf(cpuPerc.getIdle()));

     heartInfo.setLasttime(new Date());

     ctx.writeAndFlush(heartInfo);

 }catch (Exception e){
     e.printStackTrace();
 }

}
}
首先，为了方便在心跳任务中进行读写操作，HeartTask持有ChannelHandlerContext的引用。其次，为了方便收集系统的内存、CPU信息，这里使用了Sigar，也是在实际中引用非常广泛的一个工具。

Server

package day4;

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;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public class Server {

public static void main(String[] args) throws Exception{

  EventLoopGroup pGroup = new NioEventLoopGroup();
  EventLoopGroup cGroup = new NioEventLoopGroup();
  
  ServerBootstrap b = new ServerBootstrap();
  b.group(pGroup, cGroup)
   .channel(NioServerSocketChannel.class)
   .option(ChannelOption.SO_BACKLOG, 1024)
   //设置日志
   .handler(new LoggingHandler(LogLevel.INFO))
   .childHandler(new ChannelInitializer<SocketChannel>() {
     protected void initChannel(SocketChannel sc) throws Exception {
        sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
        sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
        sc.pipeline().addLast(new ServerHandler());
     }
  });
  
  ChannelFuture cf = b.bind(8765).sync();
  
  cf.channel().closeFuture().sync();
  pGroup.shutdownGracefully();
  cGroup.shutdownGracefully();

}
}

Server Handler

package day4;

import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**

Created by zhangfengzhe on 2017/2/4.
*/
public class ServerHandler extends ChannelHandlerAdapter {

//KEY: ip:port VALUE: HeartInfo
private Map<String,HeartInfo> heartInfoMap = new HashMap<String, HeartInfo>();

private static final List authList = new ArrayList();

static {
//从其他地方加载出来的IP列表
authList.add(“192.168.99.219:8765”);
}

//服务器会接收到2种消息一个是客户端初始化时发送过来的认证信息第二个是心跳信息
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
```
 if(msg instanceof String){

     if(authList.contains(msg)){ //验证通过
         ctx.writeAndFlush("OK");
     }else{
         ctx.writeAndFlush("不在认证列表中...");
     }

 }else if(msg instanceof HeartInfo){

     System.out.println((HeartInfo)msg);

     ctx.writeAndFlush("心跳接收成功!");

     HeartInfo heartInfo = (HeartInfo)msg;
     heartInfoMap.put(heartInfo.getIp() + ":" + heartInfo.getPort(),heartInfo);
 }
```
}
}

到这里，心跳检测就实现了，就这么简单，你会了么，See U~

本文出自 “学海无涯心境无限” 博客.

Netty实践（四）：心跳检测实现

标签：netty 心跳检测

原文地址：http://www.tofacebook.com/post/17027

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第三阶段，JavaEE高级框架：Netty实践（四）—— 心跳检测实现

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