如何使用Curator监听zookeeper事件变化

掌握zookeeper事件监听机制，非常重要，可以说是跨入了进阶的门槛，只有掌握了如何监听某个节点或路径，我们才能在节点变化后，做一些我们想做的事，包括： 
1，配置文件同步 
2，主从切换 
3，分布式队列 
4，分布式锁 
5，其他 

本篇我们就来看下，如何使用curator来完成监听，代码如下： 

package com.qin.curator.zk;

import javax.sound.midi.Patch;

import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.CuratorFrameworkFactory.Builder;
import org.apache.curator.framework.api.CuratorWatcher;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.utils.ZKPaths;
import org.apache.zookeeper.WatchedEvent;
/**
 * 
 * 使用curator监听zookeeper节点
 * @author qindongliang
 * **/
public class CuratorWatch {
    
    static CuratorFramework zkclient=null;
    static String nameSpace="php";
    static {
        
          String zkhost="192.168.46.22:2181";//zk的host
          RetryPolicy rp=new ExponentialBackoffRetry(1000, 3);//重试机制
          Builder builder = CuratorFrameworkFactory.builder().connectString(zkhost)
                  .connectionTimeoutMs(5000)
                  .sessionTimeoutMs(5000)
                  .retryPolicy(rp);
          builder.namespace(nameSpace);
          CuratorFramework zclient = builder.build();
          zkclient=zclient;
          zkclient.start();// 放在这前面执行
          zkclient.newNamespaceAwareEnsurePath(nameSpace);
          
    }
    
    
    public static void main(String[] args) throws Exception{
        
        
        watch();
        Thread.sleep(Long.MAX_VALUE);
        
    }
    
    
    /**
     * 
     * 监听节点变化
     * 
     * */
    public static void watch()throws Exception{
        PathChildrenCache cache = new PathChildrenCache(zkclient, "/zk", false);
        cache.start();
        
        System.out.println("监听开始/zk........");
        PathChildrenCacheListener plis=new PathChildrenCacheListener() {
            
            @Override
            public void childEvent(CuratorFramework client, PathChildrenCacheEvent event)
                    throws Exception {
                  switch ( event.getType() )
                    {
                        case CHILD_ADDED:
                        {
                            System.out.println("Node added: " + ZKPaths.getNodeFromPath(event.getData().getPath()));
                            break;
                        }
                        
                        
                        case CHILD_UPDATED:
                        {
                            System.out.println("Node changed: " + ZKPaths.getNodeFromPath(event.getData().getPath()));
                            break;
                        }

                        case CHILD_REMOVED:
                        {
                            System.out.println("Node removed: " + ZKPaths.getNodeFromPath(event.getData().getPath()));
                            break;
                        }
                    }
                
                
            }
        };
        //注册监听
        cache.getListenable().addListener(plis);
       
    }
    
    
    

}

运行后的控制台打印： 

18:33:07.722 [main] INFO  o.a.c.f.imps.CuratorFrameworkImpl - Starting
18:33:07.727 [main] DEBUG o.a.curator.CuratorZookeeperClient - Starting
18:33:07.727 [main] DEBUG org.apache.curator.ConnectionState - Starting
18:33:07.727 [main] DEBUG org.apache.curator.ConnectionState - reset
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:zookeeper.version=3.4.6-1569965, built on 02/20/2014 09:09 GMT
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:host.name=QINDONGLIANG.dhgatecn.msf
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.version=1.7.0_04
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.vendor=Oracle Corporation
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.home=D:Javajdk1.7.0_04jre
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.class.path=D:eclipseworkspace2ywopzkin;D:eclipseworkspace2ywopzklibcurator-client-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-examples-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-framework-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-recipes-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-test-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-x-discovery-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-x-discovery-server-2.6.0.jar;D:eclipseworkspace2ywopzklibcurator-x-rpc-2.6.0.jar;D:eclipseworkspace2ywopzkliblog4j-1.2.15.jar;D:eclipseworkspace2ywopzklibzookeeper-3.4.5.jar;D:eclipseworkspace2ywopzklibcommons-io-2.1.jar
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.library.path=D:Javajdk1.7.0_04in;C:WindowsSunJavain;C:Windowssystem32;C:Windows;D:/Java/jdk1.7.0_04/bin/../jre/bin/server;D:/Java/jdk1.7.0_04/bin/../jre/bin;D:/Java/jdk1.7.0_04/bin/../jre/lib/amd64;C:Program FilesCommon FilesMicrosoft SharedWindows Live;C:Program Files (x86)Common FilesMicrosoft SharedWindows Live;D:Javajdk1.7.0_04in;D:Javajdk1.7.0_04jrein;D:apache-ant-1.9.3in;C:Windowssystem32;C:Windows;C:WindowsSystem32Wbem;C:WindowsSystem32WindowsPowerShellv1.0;C:Program Files (x86)LenovoLenovo Home;C:Program Files (x86)Windows LiveShared;C:Program FilesTortoiseSVNin;D:hadoop-2.2.0/bin;C:MyProgramFilesapache-maven-3.0.5in;D:python;E:eclipse;;.
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.io.tmpdir=C:UsersQINDON~1AppDataLocalTemp
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:java.compiler=<NA>
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:os.name=Windows 7
18:33:07.734 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:os.arch=amd64
18:33:07.735 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:os.version=6.1
18:33:07.735 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:user.name=qindongliang
18:33:07.735 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:user.home=C:Usersqindongliang
18:33:07.735 [main] INFO  org.apache.zookeeper.ZooKeeper - Client environment:user.dir=D:eclipseworkspace2ywopzk
18:33:07.735 [main] INFO  org.apache.zookeeper.ZooKeeper - Initiating client connection, connectString=192.168.46.22:2181 sessionTimeout=5000 watcher=org.apache.curator.ConnectionState@2c351b05
18:33:07.738 [main] DEBUG org.apache.zookeeper.ClientCnxn - zookeeper.disableAutoWatchReset is false
18:33:07.760 [main-SendThread(192.168.46.22:2181)] INFO  org.apache.zookeeper.ClientCnxn - Opening socket connection to server 192.168.46.22/192.168.46.22:2181. Will not attempt to authenticate using SASL (unknown error)
18:33:07.761 [main-SendThread(192.168.46.22:2181)] INFO  org.apache.zookeeper.ClientCnxn - Socket connection established to 192.168.46.22/192.168.46.22:2181, initiating session
18:33:07.762 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Session establishment request sent on 192.168.46.22/192.168.46.22:2181
18:33:07.766 [main-SendThread(192.168.46.22:2181)] INFO  org.apache.zookeeper.ClientCnxn - Session establishment complete on server 192.168.46.22/192.168.46.22:2181, sessionid = 0x148ac15236f0046, negotiated timeout = 5000
18:33:07.771 [main-EventThread] INFO  o.a.c.f.state.ConnectionStateManager - State change: CONNECTED
18:33:08.784 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:null serverPath:null finished:false header:: 1,3  replyHeader:: 1,233,0  request:: '/php,F  response:: s{117,117,1411712541330,1411712541330,0,5,0,0,0,3,204} 
18:33:08.784 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x148ac15236f0046 after 4ms
监听开始/zk........
18:33:08.795 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:null serverPath:null finished:false header:: 2,3  replyHeader:: 2,233,0  request:: '/php,F  response:: s{117,117,1411712541330,1411712541330,0,5,0,0,0,3,204} 
18:33:08.797 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:null serverPath:null finished:false header:: 3,3  replyHeader:: 3,233,0  request:: '/php/zk,F  response:: s{151,182,1411714954448,1411716422668,2,5,0,0,9,3,228} 
18:33:08.804 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:/php/zk serverPath:/php/zk finished:false header:: 4,12  replyHeader:: 4,233,0  request:: '/php/zk,T  response:: v{'bb,'cc,'cc334},s{151,182,1411714954448,1411716422668,2,5,0,0,9,3,228} 
18:33:08.815 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:/php/zk/bb serverPath:/php/zk/bb finished:false header:: 5,4  replyHeader:: 5,233,0  request:: '/php/zk/bb,T  response:: #6920616d2061207a6b20636f6e74656e742031,s{152,156,1411714954452,1411714982893,2,0,0,0,19,0,152} 
18:33:08.816 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:/php/zk/cc serverPath:/php/zk/cc finished:false header:: 6,4  replyHeader:: 6,233,0  request:: '/php/zk/cc,T  response:: #63313163,s{185,222,1411716737805,1411725726750,3,0,0,0,4,0,185} 
18:33:08.817 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Reading reply sessionid:0x148ac15236f0046, packet:: clientPath:/php/zk/cc334 serverPath:/php/zk/cc334 finished:false header:: 7,4  replyHeader:: 7,233,0  request:: '/php/zk/cc334,T  response:: #636363,s{189,226,1411716744253,1411725775109,2,3,0,0,3,3,220} 
Node added: bb
Node added: cc
Node added: cc334
18:33:10.482 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x148ac15236f0046 after 1ms
18:33:12.148 [main-SendThread(192.168.46.22:2181)] DEBUG org.apache.zookeeper.ClientCnxn - Got ping response for sessionid: 0x148ac15236f0046 after 1ms