1、目的
zookeeper是一个分布式服务管理框架。zookeeper提供了对client的通知。即在server端的节点有改动或者删除的时候，能够给client进行通知。

2、server端部署
server端部署zookeeper的步骤省略。详细的能够參看我前面的文章。部署也比較简单。

3、client接收通知代码

import java.io.IOException;
import java.util.List;import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;class Wa implements Runnable
{public void run() {//连接启动ktry {ZooKeeper zk = new ZooKeeper("10.218.137.73:2181", 500000,new Watcher() {// 监控全部被触发的事件public void process(WatchedEvent event) {System.out.println("changing...");}});//设置监听器 Watcher wc = new Watcher() {public void process(WatchedEvent event) {// TODO Auto-generated method stubif (event.getType() == EventType.NodeDataChanged) {  System.out.println("change"); }  if (event.getType() == EventType.NodeDeleted){  System.out.println("dele");  }  if(event.getType()== EventType.NodeCreated){ System.out.println("create"); }}};//进行轮询。当中exists方法用来询问状态，而且设置了监听器，假设发生变化，则会回调监听器里的方法。

while(true) { zk.exists("/jianghuiwen", wc); } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (KeeperException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } public class Main { public static void main(String[] args) throws IOException, KeeperException, InterruptedException { // TODO Auto-generated method stub Thread t = new Thread(new Wa()); t.start(); } }

直接贴了代码，没有加上各种jar包，假设同学们要执行的话，须要先设置一下相关的jar包。应该就是Log4j和zookeeper的包。

4、測试
利用zookeeper自带的zkCli.sh或者用其它对节点进行改动的client进行改动节点。能够发现我们得到了以下的输出：