众所周知Curator框架是Netflix公司开源的一套Zookeeper client library。

他简化了zk client很多复杂的操作，如事件、异常、重连、集群等功能的简化和二次封装，省去了我们对zk client的设计与实现过程，让我们直接关注业务细节。

Curator框架的文档不多，但API也相对简单，也比较优雅，他实现了Fluent interface风格。

Demo:

package com.test.zookeeper_test;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;

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.ACLProvider;
import org.apache.curator.framework.imps.DefaultACLProvider;
import org.apache.curator.framework.recipes.cache.ChildData;
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.state.ConnectionState;
import org.apache.curator.framework.state.ConnectionStateListener;
import org.apache.curator.retry.RetryNTimes;
import org.apache.curator.utils.ZKPaths;
import org.apache.zookeeper.ZooDefs.Perms;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Id;
import org.apache.zookeeper.server.auth.DigestAuthenticationProvider;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;


public class CuratorFrameworkTest {

	private Logger logger = LoggerFactory.getLogger(getClass());
	private final String url = "10.1.1.35:2181,10.1.1.35:2281"; 
	private final int connectionTimeoutMs = 10 * 1000;
	private final int sleepMsBetweenRetries = 5000;
	private final int sessionTimeoutMs = 20 * 1000;
	private final String path = "/app";
	private final boolean cacheData = true;
	private CuratorFramework client;
	
	@Test
	public void startup(){
		
		final java.util.concurrent.CountDownLatch counter = new CountDownLatch(1);
		ConnectionStateListener connectionStateListener = new ConnectionStateListener() {
			
			public void stateChanged(CuratorFramework client, ConnectionState newState) {
				// TODO Auto-generated method stub
				if (newState == ConnectionState.CONNECTED) {
					
					logger.info("state:{}", ConnectionState.CONNECTED);
					counter.countDown();
					
				}
			}
		};
		
		client.getConnectionStateListenable().addListener(connectionStateListener);
		client.start();
		try {
			counter.await();
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			logger.error("", e);
		}
		
		client.getConnectionStateListenable().removeListener(connectionStateListener);
		
		String fullPath = ZKPaths.makePath(path, "/4"); // 监听节点/app/4的变化
		final PathChildrenCache childrenCache = new PathChildrenCache(client, fullPath, cacheData);
		
		childrenCache.getListenable().addListener(new PathChildrenCacheListener() {
			
			public void childEvent(CuratorFramework client, PathChildrenCacheEvent event)
					throws Exception {
				// TODO Auto-generated method stub
				logger.info("client:{}, event:{}", client, event);
				
				List<ChildData> currentData = childrenCache.getCurrentData();
				for (ChildData childData : currentData) {
					
					logger.info("path:{}, data:{}", childData.getPath(), new String(childData.getData()));
				}
				
			}
		});
		try {
			childrenCache.start();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			logger.error("", e);
		}
		
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		String command;
		try {
			while((command = reader.readLine()) != null){
				logger.info("command:{}", command);
				if (command.equalsIgnoreCase("quit")) {
					break;
				}
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		logger.info("finashed!");
		
	}
	
	
	@Before
	public void init() throws NoSuchAlgorithmException{
		logger.info("init");
		Builder builder = CuratorFrameworkFactory.builder().connectString(url).connectionTimeoutMs(connectionTimeoutMs);
		// 设定重试策略
		builder = builder.retryPolicy(new RetryNTimes(Integer.MAX_VALUE, sleepMsBetweenRetries)).sessionTimeoutMs(sessionTimeoutMs);
		
		ArrayList<ZkConf> aclConf = Lists.newArrayList(
					new ZkConf("/app", "u1001", "p1001", Perms.READ),
					new ZkConf("/app/4", "u1001", "p1001", Perms.ALL)
				);
		ACLProvider aclProvider = new PathDefaultACLProvider(aclConf);
		client = builder.aclProvider(aclProvider).build();
		
	}
	
	@After
	public void destory(){
		logger.info("destory");
		if (client != null) {
			client.close();
		}
	}
	
	
	class PathDefaultACLProvider extends DefaultACLProvider{
		private final Map<String, List<ACL>> aclMap = Maps.newHashMap();
		
		public PathDefaultACLProvider(List<ZkConf> conf) throws NoSuchAlgorithmException {
			// TODO Auto-generated constructor stub
			for (ZkConf zkConf : conf) {
				
				String idPassword = zkConf.getUid() + ':' + zkConf.getPwd();
	            Id id = new Id("digest", DigestAuthenticationProvider.generateDigest(idPassword));
	            ACL acl = new ACL(zkConf.getPerms(), id);
	            aclMap.put(zkConf.getPath(), Lists.newArrayList(acl));
				
			}
		}
		
		@Override
		public List<ACL> getDefaultAcl() {
			// TODO Auto-generated method stub
			return super.getDefaultAcl();
		}
		
		@Override
		public List<ACL> getAclForPath(String path) {
			// TODO Auto-generated method stub
			return aclMap.get(path);
		}
		
	}
	
	
	class ZkConf{
		private final String path;
		private final String uid;
		private final String pwd;
		private final int perms;
		
		public ZkConf(String path, String uid, String pwd, int perms) {
			super();
			this.path = path;
			this.uid = uid;
			this.pwd = pwd;
			this.perms = perms;
		}
		public String getPath() {
			return path;
		}
		public String getUid() {
			return uid;
		}
		public String getPwd() {
			return pwd;
		}
		public int getPerms() {
			return perms;
		}
		
	}
	
}

pom.xml

<dependencies>
	
		<!-- logger -->
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-access</artifactId>
			<version>1.1.2</version>
		</dependency>
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-core</artifactId>
			<version>1.1.2</version>
		</dependency>
		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-classic</artifactId>
			<version>1.1.2</version>
		</dependency>
		<dependency>
			<groupId>org.apache.zookeeper</groupId>
			<artifactId>zookeeper</artifactId>
			<version>3.4.6</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>1.6.1</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-log4j12</artifactId>
			<version>1.6.1</version>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>
		
		<!-- curator -->
		<dependency>
		    <groupId>org.apache.curator</groupId>
		    <artifactId>curator-framework</artifactId>
		    <version>2.4.2</version>
		</dependency>
		<dependency>
	            <groupId>org.apache.curator</groupId>
	            <artifactId>curator-client</artifactId>
	            <version>2.4.2</version>
	        </dependency>
		<dependency>
	            <groupId>org.apache.curator</groupId>
	            <artifactId>curator-recipes</artifactId>
	            <version>2.4.2</version>
	        </dependency>
</dependencies>

参考资源：

http://curator.apache.org/curator-framework/index.html

http://macrochen.iteye.com/blog/1366136