系列文章：

zookeeper快速入门一：zookeeper安装与启动-CSDN博客

zookeeper快速入门二：zookeeper基本概念-CSDN博客

zookeeper快速入门三：zookeeper的基本操作

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先启动zookeeper服务端。

在maven引入zookeeper依赖。

<dependency><groupId>org.apache.hadoop</groupId><artifactId>zookeeper</artifactId><version>3.3.1</version>
</dependency>

org.apache.zookeeper.Zookeeper是客户端入口主类，负责建立与server的会话。它提供了以下 所示几类主要方法。 

 

在java中启动客户端，注册一个watcher监听链接的建立。

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;public class ZookeeperClient {private static final String connectString = "127.0.0.1:2181";private static final int sessionTimeout = 2000;private static ZooKeeper zkClient = null;public void init() throws Exception {zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {@Overridepublic void process(WatchedEvent event) {// 收到事件通知后的回调函数（应该是我们自己的事件处理逻辑）System.out.println("zookeeper链接建立");}});}
}

在main方法里测试我们的init方法，用Thread.sleep方法等待zookeeper连接创建，不然在zookeeper客户端建立连接之前主线程就已经退出。

    public static void main(String[] args)throws Exception{new ZookeeperClient().init();Thread.sleep(5000);}

控制台输出：

接下来我们创建一个名为“/java”的节点，节点数据为“data”，ZooDefs.Ids.OPEN_ACL_UNSAFE的意思是不节点能被所有人访问，CreateMode.PERSISTENT：节点的类型为持久节点。

    public void createZnode()throws Exception{zkClient.create("/java", "data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}

判断节点是否存在，false代表不注册监听事件，如果是true，则注册我们在new zookeeper方法里面传递的watcher。

    public void testExist() throws Exception{Stat stat = zkClient.exists("/java", false);System.out.println(stat==null?"节点不存在":"节点存在");}

测试一下我们的方法。

    public static void main(String[] args)throws Exception{new ZookeeperClient().init();Thread.sleep(5000);new ZookeeperClient().createZnode();new ZookeeperClient().testExist();}

 获取节点的数据。false和上面exists方法参数含义一样，表示不注册连接建立时的watcher，第三个stat对象则存储了除了节点数据之外的其他信息，如czxid、mzxid等。如果为null则表示不保存节点的这些信息。

    public void getNodeData()throws Exception{byte[] res = zkClient.getData("/java",false,new Stat());System.out.println(new String(res));}

同样测试我们的方法。

    public static void main(String[] args)throws Exception{new ZookeeperClient().init();Thread.sleep(3000);new ZookeeperClient().getNodeData();}

 获取ACL控制列表

    public void getACl()throws Exception{List<ACL> res = zkClient.getACL("/java",new Stat());for(ACL acl : res){System.out.println(acl.getId().toString()+acl.getPerms());}}

测试：

    public static void main(String[] args)throws Exception{new ZookeeperClient().init();Thread.sleep(3000);new ZookeeperClient().getACl();}

在/java下创建子节点，获取子节点列表。

    public void createChildZnode()throws Exception{zkClient.create("/java/child", "child data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);zkClient.create("/java/child2", "child2 data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}public void getChildNode()throws Exception{List<String> res = zkClient.getChildren("/java",false);for(String s : res){System.out.println(s);}}

测试：

    public static void main(String[] args)throws Exception{new ZookeeperClient().init();Thread.sleep(3000);new ZookeeperClient().createChildZnode();new ZookeeperClient().getChildNode();}

全部代码如下：

import org.apache.zookeeper.*;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Stat;import java.util.List;public class ZookeeperClient {private static final String connectString = "127.0.0.1:2181";private static final int sessionTimeout = 2000;private static ZooKeeper zkClient = null;public void init() throws Exception {zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() {@Overridepublic void process(WatchedEvent event) {// 收到事件通知后的回调函数（应该是我们自己的事件处理逻辑）System.out.println("zookeeper链接建立");}});}public void createZnode()throws Exception{zkClient.create("/java", "data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}public void createChildZnode()throws Exception{zkClient.create("/java/child", "child data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);zkClient.create("/java/child2", "child2 data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);}public void getChildNode()throws Exception{List<String> res = zkClient.getChildren("/java",false);for(String s : res){System.out.println(s);}}public void testExist() throws Exception{Stat stat = zkClient.exists("/java", false);System.out.println(stat==null?"节点不存在":"节点存在");}public void getNodeData()throws Exception{byte[] res = zkClient.getData("/java",false,new Stat());System.out.println(new String(res));}public void getACl()throws Exception{List<ACL> res = zkClient.getACL("/java",new Stat());for(ACL acl : res){System.out.println(acl.getId().toString()+acl.getPerms());}}public static void main(String[] args)throws Exception{new ZookeeperClient().init();Thread.sleep(3000);new ZookeeperClient().createChildZnode();new ZookeeperClient().getChildNode();}}