ZooKeeper原生的API支持通過注冊Watcher來進行事件監聽，但是Watcher通知是一次性的，因此開發過程中需要反復注冊Watcher，比較繁瑣。Curator引入了Cache來監聽ZooKeeper服務端的事件。Cache對ZooKeeper事件監聽進行了封裝，能夠自動處理反復注冊監聽，簡化了ZooKeeper原生API繁瑣的開發過程。

簡單的示例：

package com.huey.dream.demo;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import org.apache.curator.framework.CuratorFramework;import org.apache.curator.framework.CuratorFrameworkFactory;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.framework.recipes.cache.PathChildrenCache.StartMode;import org.apache.curator.retry.ExponentialBackoffRetry;/** * Curator事件監聽 * @author  huey * @version 1.0  * @created 2015-3-2 */public class CarutorDemo {    public static void main(String[] args) throws Exception {        CuratorFramework client = CuratorFrameworkFactory.builder()            .connectString("192.168.1.109:2181")            .sessionTimeoutMs(5000)            .connectionTimeoutMs(3000)            .retryPolicy(new ExponentialBackoffRetry(1000, 3))            .build();        client.start();                client.create()            .creatingParentsIfNeeded()            .forPath("/zk-huey/cnode", "hello".getBytes());                /**         * 在注冊監聽器的時候，如果傳入此參數，當事件觸發時，邏輯由線程池處理         */        ExecutorService pool = Executors.newFixedThreadPool(2);                /**         * 監聽數據節點的變化情況         */        final NodeCache nodeCache = new NodeCache(client, "/zk-huey/cnode", false);        nodeCache.start(true);        nodeCache.getListenable().addListener(            new NodeCacheListener() {                @Override                public void nodeChanged() throws Exception {                    System.out.