/**
*　構造器
* @param connectString 集群的IP：端口號；多個服務器時，中間用逗號分割
* @param sessionTimeout 超時時間，單位：毫秒
* @param watcher  監(jiān)聽器，監(jiān)聽節(jié)點變化
* @throws IOException
*/
public ZooKeeper(String connectString, int sessionTimeout, Watcher watcher) throws IOException

/**
*
* @param path 節(jié)點路徑
* @param data 數據
* @param acl 訪問控制列表
* @param createMode 節(jié)點類型
* @return
* @throws KeeperException
* @throws InterruptedException
*/
public String create(String path, byte[] data, List<ACL> acl, CreateMode createMode) throws KeeperException, InterruptedException

/**
*
* @param path 節(jié)點路徑
* @param watch 監(jiān)聽器
* @return 所有的子節(jié)點的名稱
* @throws KeeperException
* @throws InterruptedException
*/
public List<String> getChildren(String path, boolean watch) throws KeeperException, InterruptedException

/**
*
* @param path 節(jié)點路徑
* @param watcher 監(jiān)聽器
* @param stat  狀態(tài)信息【可以為null】
* @return 節(jié)點數據的二進制數組【可以通過new String()轉換成字符串信息】
* @throws KeeperException
* @throws InterruptedException
*/
public byte[] getData(String path, Watcher watcher, Stat stat) throws KeeperException, InterruptedException

/**
*
* @param path 節(jié)點路徑
* @param watch 監(jiān)聽器
* @param cb 回調函數
* @param ctx  上下文參數 ？【該參數不太理解，望知道的留言講解，謝謝】
*/
public void getData(String path, boolean watch, AsyncCallback.DataCallback cb, Object ctx)

/**
*
* @param path 節(jié)點路徑
* @param data 數據
* @param version 版本號【初始通常賦值為-1，每次更新會自動+1】
* @return  狀態(tài)信息
* @throws KeeperException
* @throws InterruptedException
*/
public Stat setData(String path, byte[] data, int version) throws KeeperException, InterruptedException

/**
*如果Stat為null，則節(jié)點不存在
* @param path 節(jié)點路徑
* @param watch 監(jiān)聽器
* @return 狀態(tài)信息
* @throws KeeperException
* @throws InterruptedException
*/
public Stat exists(String path, boolean watch) throws KeeperException, InterruptedException

/**
* 如果要刪除的節(jié)點有子節(jié)點，會報錯：KeeperException$NotEmptyException: KeeperErrorCode = Directory not empty for
* 如果節(jié)點不存在，會報錯：KeeperException$NoNodeException: KeeperErrorCode = NoNode for
* @param path 節(jié)點路徑
* @param version 版本號[version = -1 : 匹配所有的版本]
* @throws InterruptedException
* @throws KeeperException
*/
public void delete(String path, int version) throws InterruptedException, KeeperException

try {
  ZooKeeper　zooKeeper = new ZooKeeper("172.23.34.13:2181", 15000, event -> {
        if (event.getType() == Watcher.Event.EventType.None && event.getState() == Watcher.Event.KeeperState.SyncConnected) {
            System.out.println("Connectted successful.");
        }
    });
} catch (IOException e) {
    e.printStackTrace();
}

@Test
public void create() throws KeeperException, InterruptedException {
    //參數：1，節(jié)點路徑； 2，要存儲的數據； 3，節(jié)點的權限； 4，節(jié)點的類型
    String nodePath = zooKeeper.create("/java/2183", "This is Java Node 2183.".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    System.out.println(nodePath);
}

public void getChildren() throws KeeperException, InterruptedException {
    List<String> children = zooKeeper.getChildren("/", true);
    for (String child : children) {
        System.out.println("child: "+child);
    }
}

@Test
public void getData() throws KeeperException, InterruptedException {
    String path = "/java";
    byte[] bytes = zooKeeper.getData(path, event -> {
        if (event.getType() == Watcher.Event.EventType.NodeDataChanged && path.equals(event.getPath())) {
            System.out.println("Date changed.");
        }
    }, null);
    System.out.printf("The data of %s is : %s \n",path, new String(bytes));
}

@Test
public void getDataAsync() {
    String path = "/java";
    zooKeeper.getData(path, false, new AsyncCallback.DataCallback() {
        @Override
        public void processResult(int i, String s, Object o, byte[] bytes, Stat stat) {
            System.out.printf("The data of %s is : %s \n",path, new String(bytes));
        }
    },"1000");

    //休眠20秒，查看響應結果
    try {
        Thread.sleep(20000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

@Test
public void setData() throws KeeperException, InterruptedException {
    Stat stat = zooKeeper.setData("/java", "This is from java.".getBytes(), -1);
    //更新節(jié)點后，version會自動+1。故，返回值為0
    System.out.println(stat.getAversion());
}

@Test
public void setDataThread() throws KeeperException, InterruptedException {
    String path = "/java";
    Stat stat = new Stat();
    //1,先獲取節(jié)點的當前版本
    zooKeeper.getData(path,false,stat);
    //2，在當前版本的基礎上修改節(jié)點內容
    zooKeeper.setData(path, "This is from java.".getBytes(), stat.getVersion());
}

@Test
public void exists() throws KeeperException, InterruptedException {
    Stat stat = zooKeeper.exists("/java", false);
    if (stat == null) {
        System.out.println("Not Exists.");
    }else {
        System.out.println("Exists.");
    }
}

@Test
public void delete() throws KeeperException, InterruptedException {
    //version = -1 : 匹配所有的版本
    zooKeeper.delete("/java/2182", -1);
}