ZK节点介绍和基本操作

一、基本介绍

1 、PERSISTENT (0, false, false),  

          持久节点：节点创建后，会一直存在，不会因客户端会话失效而删除；

2、PERSISTENT_SEQUENTIAL (2, false, true),  

         持久顺序节点：基本特性与持久节点一致，创建节点的过程中，zookeeper会在其名字后自动追加一个单调增长的数字后缀，作为新的节点名；  

3、EPHEMERAL (1, true, false),  

        临时节点：客户端会话失效或连接关闭后，该节点会被自动删除，且不能再临时节点下面创建子节点，否则报如下错（org.apache.zookeeper.KeeperException$NoChildrenForEphemeralsException: KeeperErrorCode = NoChildrenForEphemerals for /node/child）；

 

 4、EPHEMERAL_SEQUENTIAL (3, true, true);

         临时顺序节点：基本特性与临时节点一致，创建节点的过程中，zookeeper会在其名字后自动追加一个单调增长的数字后缀，作为新的节点名；  

    

    二、JavaApi的操作

  1）maven引入

   

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <dependency>
        <groupId>org.apache.zookeeper</groupId>
        <artifactId>zookeeper</artifactId>
        <version>3.4.12</version>
    </dependency>
    <dependency>
        <groupId>com.101tec</groupId>
        <artifactId>zkclient</artifactId>
        <version>0.10</version>
    </dependency>


    <dependency>
        <groupId>org.apache.curator</groupId>
        <artifactId>curator-framework</artifactId>
        <version>4.0.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.curator</groupId>
        <artifactId>curator-recipes</artifactId>
        <version>4.0.0</version>
    </dependency>
</dependencies>

 2）Java基本节点的操作

public class ZkClientOperator {

    /** zookeeper地址 */
    static final String CONNECT_ADDR = "192.168.112.131:2181";
    /** session超时时间 */
    static final int SESSION_OUTTIME = 10000;//ms

    /**
     * 主要测试增加 临时节点、持久化节点，以及读取内容，删除节点操作
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
       //ZkClient zkc = new ZkClient(new ZkConnection(CONNECT_ADDR), SESSION_OUTTIME);
        ZkClient zkc = new ZkClient(CONNECT_ADDR, SESSION_OUTTIME);

        //1. create and delete方法
        zkc.createEphemeral("/temp");
        zkc.createPersistent("/super/c1", true);

        Thread.sleep(10000);
        zkc.delete("/temp");
        zkc.deleteRecursive("/super");

        //2. 设置path和data 并且读取子节点和每个节点的内容
        zkc.createPersistent("/super", "1234");
        zkc.createPersistent("/super/c1", "c1内容");
        zkc.createPersistent("/super/c2", "c2内容");

        List<String> list = zkc.getChildren("/super");
        for(String p : list){
            System.out.println(p);
            String rp = "/super/" + p;
            String data = zkc.readData(rp);
            System.out.println("节点为：" + rp + "，内容为: " + data);
        }

        //3. 更新和判断节点是否存在
        zkc.writeData("/super/c1", "新内容");
        System.out.println(zkc.readData("/super/c1").toString());
        System.out.println(zkc.exists("/super/c1"));

//    4.递归删除/super内容
        zkc.deleteRecursive("/super");
    }
}

3）测试watcher事件

public class ZooKeeperWatcher implements Watcher  {


    /** 定义原子变量 */
    AtomicInteger seq = new AtomicInteger();
    /** 定义session失效时间 */
    private static final int SESSION_TIMEOUT = 10000;
    /** zookeeper服务器地址 */
    private static final String CONNECTION_ADDR = "192.168.112.131:2181";
    /** zk父路径设置 */
    private static final String PARENT_PATH = "/testWatch";
    /** zk子路径设置 */
    private static final String CHILDREN_PATH = "/testWatch/children";
    /** 进入标识 */
    private static final String LOG_PREFIX_OF_MAIN = "【Main】";
    /** zk变量 */
    private ZooKeeper zk = null;
    /** 信号量设置，用于等待zookeeper连接建立之后 通知阻塞程序继续向下执行 */
    private CountDownLatch connectedSemaphore = new CountDownLatch(1);


    /**
     * 创建ZK连接
     * @param connectAddr ZK服务器地址列表
     * @param sessionTimeout Session超时时间
     */
    public void createConnection(String connectAddr, int sessionTimeout) {
        this.releaseConnection();
        try {
            zk = new ZooKeeper(connectAddr, sessionTimeout, this);
            System.out.println(LOG_PREFIX_OF_MAIN + "开始连接ZK服务器");
            connectedSemaphore.await();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    /**
     * 关闭ZK连接
     */
    public void releaseConnection() {
        if (this.zk != null) {
            try {
                this.zk.close();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }


    /**
     * 创建节点
     * @param path 节点路径
     * @param data 数据内容
     * @return
     */
    public boolean createPath(String path, String data) {
        try {
            //设置监控(由于zookeeper的监控都是一次性的所以 每次必须设置监控)
            this.zk.exists(path, true);
            System.out.println(LOG_PREFIX_OF_MAIN + "节点创建成功, Path: " +
                    this.zk.create(    /**路径*/
                            path,
                            /**数据*/
                            data.getBytes(),
                            /**所有可见*/
                            ZooDefs.Ids.OPEN_ACL_UNSAFE,
                            /**永久存储*/
                            CreateMode.PERSISTENT ) +
                    ", content: " + data);
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }

    /**
     * 读取指定节点数据内容
     * @param path 节点路径
     * @return
     */
    public String readData(String path, boolean needWatch) {
        try {
            return new String(this.zk.getData(path, needWatch, null));
        } catch (Exception e) {
            e.printStackTrace();
            return "";
        }
    }

    /**
     * 更新指定节点数据内容
     * @param path 节点路径
     * @param data 数据内容
     * @return
     */
    public boolean writeData(String path, String data) {
        try {
            System.out.println(LOG_PREFIX_OF_MAIN + "更新数据成功，path：" + path + ", stat: " +
                    this.zk.setData(path, data.getBytes(), -1));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }
    /**
     * 删除指定节点
     *
     * @param path
     *            节点path
     */
    public void deleteNode(String path) {
        try {
            this.zk.delete(path, -1);
            System.out.println(LOG_PREFIX_OF_MAIN + "删除节点成功，path：" + path);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    /**
     * 判断指定节点是否存在
     * @param path 节点路径
     */
    public Stat exists(String path, boolean needWatch) {
        try {
            return this.zk.exists(path, needWatch);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    /**
     * 获取子节点
     * @param path 节点路径
     */
    private List<String> getChildren(String path, boolean needWatch) {
        try {
            return this.zk.getChildren(path, needWatch);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    /**
     * 删除所有节点
     */
    public void deleteAllTestPath() {
        if(this.exists(CHILDREN_PATH, false) != null){
            this.deleteNode(CHILDREN_PATH);
        }
        if(this.exists(PARENT_PATH, false) != null){
            this.deleteNode(PARENT_PATH);
        }
    }

    /**
     * 收到来自Server的Watcher通知后的处理。
     */
    @Override
    public void process(WatchedEvent event) {

        System.out.println("进入 process 。。。。。event = " + event);

        try {
            Thread.sleep(200);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        if (event == null) {
            return;
        }


        // 连接状态
        Watcher.Event.KeeperState keeperState = event.getState();
        // 事件类型
        Watcher.Event.EventType eventType = event.getType();
        // 受影响的path
        String path = event.getPath();

        String logPrefix = "【Watcher-" + this.seq.incrementAndGet() + "】";

        System.out.println(logPrefix + "收到Watcher通知");
        System.out.println(logPrefix + "连接状态:	" + keeperState.toString());
        System.out.println(logPrefix + "事件类型:	" + eventType.toString());


        if (Event.KeeperState.SyncConnected == keeperState) {
            // 成功连接上ZK服务器
            if (Event.EventType.None == eventType) {
                System.out.println(logPrefix + "成功连接上ZK服务器");
                connectedSemaphore.countDown();
            }
            //创建节点
             if (Event.EventType.NodeCreated == eventType) {
                System.out.println(logPrefix + "节点创建");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                this.exists(path, true);
            }
            //更新节点
            else if (Event.EventType.NodeDataChanged == eventType) {
                System.out.println(logPrefix + "节点数据更新");
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(logPrefix + "数据内容: " + this.readData(PARENT_PATH, true));
            }
            //更新子节点
            else if (Event.EventType.NodeChildrenChanged == eventType) {
                System.out.println(logPrefix + "子节点变更");
                try {
                    Thread.sleep(3000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(logPrefix + "子节点列表：" + this.getChildren(PARENT_PATH, true));
            }
            //删除节点
            else if (Event.EventType.NodeDeleted == eventType) {
                System.out.println(logPrefix + "节点 " + path + " 被删除");
            }
        }
        else if (Watcher.Event.KeeperState.Disconnected == keeperState) {
            System.out.println(logPrefix + "与ZK服务器断开连接");
        }
        else if (Watcher.Event.KeeperState.AuthFailed == keeperState) {
            System.out.println(logPrefix + "权限检查失败");
        }
        else if (Watcher.Event.KeeperState.Expired == keeperState) {
            System.out.println(logPrefix + "会话失效");
        }
        System.out.println("--------------------------------------------");

    }


    public static void main(String[] args) throws Exception {

        //建立watcher
        ZooKeeperWatcher zkWatch = new ZooKeeperWatcher();
        //创建连接
        zkWatch.createConnection(CONNECTION_ADDR, SESSION_TIMEOUT);
        //System.out.println(zkWatch.zk.toString());

        Thread.sleep(1000);

        // 清理节点
        zkWatch.deleteAllTestPath();

        if (zkWatch.createPath(PARENT_PATH, System.currentTimeMillis() + "")) {


            // 读取数据，在操作节点数据之前先调用zookeeper的getData()方法是为了可以watch到对节点的操作。watch是一次性的，
            // 也就是说，如果第二次又重新调用了setData()方法，在此之前需要重新调用一次。
             System.out.println("---------------------- read parent ----------------------------");

          //  zkWatch.readData(PARENT_PATH, true);
            // 更新数据
           zkWatch.writeData(PARENT_PATH, System.currentTimeMillis() + "");

            /** 读取子节点，设置对子节点变化的watch，如果不写该方法，则在创建子节点是只会输出NodeCreated，而不会输出NodeChildrenChanged，
             也就是说创建子节点时没有watch。
             如果是递归的创建子节点，如path="/p/c1/c2"的话，getChildren(PARENT_PATH, ture)只会在创建c1时watch，输出c1的NodeChildrenChanged，
             而不会输出创建c2时的NodeChildrenChanged，如果watch到c2的NodeChildrenChanged，则需要再调用一次getChildren(String path, true)方法，
             其中path="/p/c1"
             */
            System.out.println("---------------------- read children path ----------------------------");
            zkWatch.getChildren(PARENT_PATH, true);

           Thread.sleep(1000);

            // 创建子节点，同理如果想要watch到NodeChildrenChanged状态，需要调用getChildren(CHILDREN_PATH, true)
            zkWatch.createPath(CHILDREN_PATH, System.currentTimeMillis() + "");

            Thread.sleep(1000);

            zkWatch.readData(CHILDREN_PATH, true);
            zkWatch.writeData(CHILDREN_PATH, System.currentTimeMillis() + "");
        }

        Thread.sleep(1000);
        // 清理节点
        zkWatch.deleteAllTestPath();
        Thread.sleep(1000);
        zkWatch.releaseConnection();
    }


}

三、Curator框架的的基本测试

  1）基本操作

  

package cn.enjoy.curator;


import org.apache.curator.RetryPolicy;
import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.api.BackgroundCallback;
import org.apache.curator.framework.api.CuratorEvent;
import org.apache.curator.framework.api.CuratorListener;
import org.apache.curator.framework.api.transaction.CuratorOp;
import org.apache.curator.framework.api.transaction.CuratorTransactionResult;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.data.Stat;
import org.junit.Before;
import org.junit.Test;




import java.util.List;


import static com.sun.xml.internal.ws.dump.LoggingDumpTube.Position.Before;


/**
* 测试Apache Curator框架的基本用法
*/
public class OperatorTest {
    //ZooKeeper服务地址
    private static final String SERVER = "127.0.0.1:2181";
    //会话超时时间
    private final int SESSION_TIMEOUT = 30000;
    //连接超时时间
    private final int CONNECTION_TIMEOUT = 5000;
    //创建连接实例
    private CuratorFramework client = null;


    /**
     * baseSleepTimeMs：初始的重试等待时间
     * maxRetries：最多重试次数
     * <p>
     * <p>
     * ExponentialBackoffRetry：重试一定次数，每次重试时间依次递增
     * RetryNTimes：重试N次
     * RetryOneTime：重试一次
     * RetryUntilElapsed：重试一定时间
     */
    RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);


    @org.junit.Before
    public void init() {
        //创建 CuratorFrameworkImpl实例
        client = CuratorFrameworkFactory.newClient(SERVER, SESSION_TIMEOUT, CONNECTION_TIMEOUT, retryPolicy);


        //启动
        client.start();
    }


    /**
     * 测试创建节点
     *
     * @throws Exception
     */
    @Test
    public void testCreate() throws Exception {
        //创建永久节点
        client.create().forPath("/curator", "/curator data".getBytes());
        //创建永久有序节点
        client.create().withMode(CreateMode.PERSISTENT_SEQUENTIAL).forPath("/curator_sequential", "/curator_sequential data".getBytes());


        //创建临时节点
        client.create().withMode(CreateMode.EPHEMERAL)
                .forPath("/curator/ephemeral", "/curator/ephemeral data".getBytes());


        //创建临时有序节点
        client.create().withMode(CreateMode.EPHEMERAL_SEQUENTIAL)
                .forPath("/curator/ephemeral_path1", "/curator/ephemeral_path1 data".getBytes());
    }




    /**
     * 测试检查某个节点是否存在
     *
     * @throws Exception
     */
    @Test
    public void testCheck() throws Exception {
        Stat stat1 = client.checkExists().forPath("/curator");
        Stat stat2 = client.checkExists().forPath("/curator2");


        System.out.println("'/curator'是否存在： " + (stat1 != null ? true : false));
        System.out.println("'/curator2'是否存在： " + (stat2 != null ? true : false));
    }


    /**
     * 测试异步设置节点数据
     *
     * @throws Exception
     */
    @Test
    public void testSetDataAsync() throws Exception {
        //创建监听器
        CuratorListener listener = new CuratorListener() {
            @Override
            public void eventReceived(CuratorFramework client, CuratorEvent event)
                    throws Exception {
                System.out.println(event.getPath());
            }
        };
        //添加监听器
        client.getCuratorListenable().addListener(listener);
        //异步设置某个节点数据
        client.setData().inBackground().forPath("/curator", "sync".getBytes());
        //为了防止单元测试结束从而看不到异步执行结果，因此暂停10秒
        Thread.sleep(10000);
    }
    /**
     * 测试另一种异步执行获取通知的方式
     *
     * @throws Exception
     */
    @Test
    public void testSetDataAsyncWithCallback() throws Exception {
        BackgroundCallback callback = new BackgroundCallback() {


            @Override
            public void processResult(CuratorFramework client, CuratorEvent event)
                    throws Exception {
                System.out.println(event.getPath());
            }
        };
        //异步设置某个节点数据
        client.setData().inBackground(callback).forPath("/curator", "/curator modified data with Callback".getBytes());


        //为了防止单元测试结束从而看不到异步执行结果，因此暂停10秒
        Thread.sleep(10000);
    }
    /**
     * 测试删除节点
     *
     * @throws Exception
     */
    @Test
    public void testDelete() throws Exception {
        //创建测试节点
        client.create().orSetData().creatingParentsIfNeeded()
                .forPath("/curator/del_key1", "/curator/del_key1 data".getBytes());
        client.create().orSetData().creatingParentsIfNeeded()
                .forPath("/curator/del_key2", "/curator/del_key2 data".getBytes());
        client.create().forPath("/curator/del_key2/test_key", "test_key data".getBytes());
        //删除该节点
        client.delete().forPath("/curator/del_key1");
        //级联删除子节点
        client.delete().guaranteed().deletingChildrenIfNeeded().forPath("/curator/del_key2");
    }
    
    /*
     * 测试事务管理：碰到异常，事务会回滚
     * @throws Exception
     */
    @Test
    public void testTransaction() throws Exception {
        //定义几个基本操作
        CuratorOp createOp = client.transactionOp().create()
                .forPath("/curator/one_path", "some data".getBytes());


        CuratorOp setDataOp = client.transactionOp().setData()
                .forPath("/curator", "other data".getBytes());


        CuratorOp deleteOp = client.transactionOp().delete()
                .forPath("/curator");


        //事务执行结果
        List<CuratorTransactionResult> results = client.transaction()
                .forOperations(createOp, setDataOp, deleteOp);


        //遍历输出结果
        for (CuratorTransactionResult result : results) {
            System.out.println("执行结果是： " + result.getForPath() + "--" + result.getType());
        }
    }
}

 2） curator监听器的测试

  

 
public class EventTest {


    //ZooKeeper服务地址
    private static final String SERVER = "192.168.30.10:2181";


    //会话超时时间
    private final int SESSION_TIMEOUT = 30000;


    //连接超时时间
    private final int CONNECTION_TIMEOUT = 5000;


    //创建连接实例
    private CuratorFramework client = null;


    /**
     * baseSleepTimeMs：初始的重试等待时间
     * maxRetries：最多重试次数
     *
     *
     * ExponentialBackoffRetry：重试一定次数，每次重试时间依次递增
     * RetryNTimes：重试N次
     * RetryOneTime：重试一次
     * RetryUntilElapsed：重试一定时间
     */
    RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);


    @org.junit.Before
    public void init(){
        //创建 CuratorFrameworkImpl实例
        client = CuratorFrameworkFactory.newClient(SERVER, SESSION_TIMEOUT, CONNECTION_TIMEOUT, retryPolicy);


        //启动
        client.start();
    }


    /**
     *
     * @描述：第一种监听器的添加方式: 对指定的节点进行添加操作
     * 仅仅能监控指定的本节点的数据修改,删除 操作 并且只能监听一次 --->不好
     */


    @Test
    public  void TestListenterOne() throws Exception{
        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","test".getBytes());


        // 注册观察者，当节点变动时触发
        byte[] data = client.getData().usingWatcher(new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                System.out.println("获取 test 节点 监听器 : " + event);
            }
        }).forPath("/test");


        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","test".getBytes());
        Thread.sleep(1000);
        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","test".getBytes());
        Thread.sleep(1000);
        System.out.println("节点数据: "+ new String(data));
        Thread.sleep(10000);
    }




    /**
     *
     * @描述：第二种监听器的添加方式: Cache 的三种实现
     *   Path Cache：监视一个路径下1）孩子结点的创建、2）删除，3）以及结点数据的更新。
     *                  产生的事件会传递给注册的PathChildrenCacheListener。
     *  Node Cache：监视一个结点的创建、更新、删除，并将结点的数据缓存在本地。
     *  Tree Cache：Path Cache和Node Cache的“合体”，监视路径下的创建、更新、删除事件，并缓存路径下所有孩子结点的数据。
     */


    //1.path Cache  连接  路径  是否获取数据
    //能监听所有的字节点 且是无限监听的模式 但是 指定目录下节点的子节点不再监听
    @Test
    public void setListenterTwoOne() throws Exception{
        ExecutorService pool = Executors.newCachedThreadPool();
        PathChildrenCache childrenCache = new PathChildrenCache(client, "/test", true);
        PathChildrenCacheListener childrenCacheListener = new PathChildrenCacheListener() {
            @Override
            public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception {
                System.out.println("开始进行事件分析:-----");
                ChildData data = event.getData();
                switch (event.getType()) {
                    case CHILD_ADDED:
                        System.out.println("CHILD_ADDED : "+ data.getPath() +"  数据:"+ data.getData());
                        break;
                    case CHILD_REMOVED:
                        System.out.println("CHILD_REMOVED : "+ data.getPath() +"  数据:"+ data.getData());
                        break;
                    case CHILD_UPDATED:
                        System.out.println("CHILD_UPDATED : "+ data.getPath() +"  数据:"+ data.getData());
                        break;
                    case INITIALIZED:
                        System.out.println("INITIALIZED : "+ data.getPath() +"  数据:"+ data.getData());
                        break;
                    default:
                        break;
                }
            }
        };
        childrenCache.getListenable().addListener(childrenCacheListener);
        System.out.println("Register zk watcher successfully!");
        childrenCache.start(PathChildrenCache.StartMode.POST_INITIALIZED_EVENT);


        //创建一个节点
        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","test".getBytes());


        client.create().orSetData().withMode(CreateMode.EPHEMERAL).forPath("/test/node01","enjoy".getBytes());
        Thread.sleep(1000);
        client.create().orSetData().withMode(CreateMode.EPHEMERAL).forPath("/test/node02","deer".getBytes());
        Thread.sleep(1000);
        client.create().orSetData().withMode(CreateMode.EPHEMERAL).forPath("/test/node02","demo".getBytes());
        Thread.sleep(1000);
        client.delete().forPath("/test/node02");
        Thread.sleep(10000);
    }


    //2.Node Cache  监控本节点的变化情况   连接 目录 是否压缩
    //监听本节点的变化  节点可以进行修改操作  删除节点后会再次创建(空节点)
    @Test
    public void setListenterTwoTwo() throws Exception{
        ExecutorService pool = Executors.newCachedThreadPool();
        //设置节点的cache
        final NodeCache nodeCache = new NodeCache(client, "/test", false);
        nodeCache.getListenable().addListener(new NodeCacheListener() {
            @Override
            public void nodeChanged() throws Exception {
                System.out.println("the test node is change and result is :");
                System.out.println("path : "+nodeCache.getCurrentData().getPath());
                System.out.println("data : "+new String(nodeCache.getCurrentData().getData()));
                System.out.println("stat : "+nodeCache.getCurrentData().getStat());
            }
        });
        nodeCache.start();


        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","test".getBytes());
        Thread.sleep(1000);
        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","enjoy".getBytes());
        Thread.sleep(10000);
    }
    //3.Tree Cache
    // 监控 指定节点和节点下的所有的节点的变化--无限监听  可以进行本节点的删除(不在创建)
    @Test
    public void TestListenterTwoThree() throws Exception{
        ExecutorService pool = Executors.newCachedThreadPool();
        //设置节点的cache
        TreeCache treeCache = new TreeCache(client, "/test");
        //设置监听器和处理过程
        treeCache.getListenable().addListener(new TreeCacheListener() {
            @Override
            public void childEvent(CuratorFramework client, TreeCacheEvent event) throws Exception {
                ChildData data = event.getData();
                if(data !=null){
                    switch (event.getType()) {
                        case NODE_ADDED:
                            System.out.println("NODE_ADDED : "+ data.getPath() +"  数据:"+ new String(data.getData()));
                            break;
                        case NODE_REMOVED:
                            System.out.println("NODE_REMOVED : "+ data.getPath() +"  数据:"+ new String(data.getData()));
                            break;
                        case NODE_UPDATED:
                            System.out.println("NODE_UPDATED : "+ data.getPath() +"  数据:"+ new String(data.getData()));
                            break;


                        default:
                            break;
                    }
                }else{
                    System.out.println( "data is null : "+ event.getType());
                }
            }
        });
        //开始监听
        treeCache.start();


        //创建一个节点
        client.create().orSetData().withMode(CreateMode.PERSISTENT).forPath("/test","test".getBytes());


        Thread.sleep(1000);
        client.create().orSetData().withMode(CreateMode.EPHEMERAL).forPath("/test/node01","enjoy".getBytes());
        Thread.sleep(1000);
        client.create().orSetData().withMode(CreateMode.EPHEMERAL).forPath("/test/node01","deer".getBytes());


        Thread.sleep(1000);
        client.create().orSetData().creatingParentsIfNeeded().withMode(CreateMode.EPHEMERAL).forPath("/test/node02/node02_2","deer".getBytes());
        Thread.sleep(10000);
    }


}