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转载:http://www.mamicode.com/info-detail-494364.html
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ZooKeeper原生的API支持通过注册Watcher来进行事件监听,但是Watcher通知是一次性的,因此开发过程中需要反复注册Watcher,比较繁琐。Curator引入了Cache来监听ZooKeeper服务端的事件。Cache对ZooKeeper事件监听进行了封装,能够自动处理反复注册监听,简化了ZooKeeper原生API繁琐的开发过程。
简单的示例:
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事件监听 * @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()); /** * 在注册监听器的时候,如果传入此参数,当事件触发时,逻辑由线程池处理 */ ExecutorService pool = Executors.newFixedThreadPool(2); /** * 监听数据节点的变化情况 */ 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.println("Node data is changed, new data: " + new String(nodeCache.getCurrentData().getData())); } }, pool ); /** * 监听子节点的变化情况 */ final PathChildrenCache childrenCache = new PathChildrenCache(client, "/zk-huey", true); childrenCache.start(StartMode.POST_INITIALIZED_EVENT); childrenCache.getListenable().addListener( new PathChildrenCacheListener() { @Override public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception { switch (event.getType()) { case CHILD_ADDED: System.out.println("CHILD_ADDED: " + event.getData().getPath()); break; case CHILD_REMOVED: System.out.println("CHILD_REMOVED: " + event.getData().getPath()); break; case CHILD_UPDATED: System.out.println("CHILD_UPDATED: " + event.getData().getPath()); break; default: break; } } }, pool ); client.setData().forPath("/zk-huey/cnode", "world".getBytes()); Thread.sleep(10 * 1000); pool.shutdown(); client.close(); } }
ZooKeeper(3.4.5) 使用Curator监听事件
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原文地址:http://www.cnblogs.com/fanguangdexiaoyuer/p/5729076.html