java连接zookeeper的3种方式小结

public class Demo { 
    private static String ip = "192.168.0.101:2181"; 
    private static int  session_timeout = 40000; 
    private static CountDownLatch latch = new CountDownLatch(1); 
    public static void main(String[] args) throws Exception {
        ZooKeeper zooKeeper = new ZooKeeper(ip, session_timeout, new Watcher() {
            @Override
            public void process(WatchedEvent watchedEvent) {
                if(watchedEvent.getState() == Event.KeeperState.SyncConnected) {
                    //确认已经连接完毕后再进行操作
                    latch.countDown();
                    System.out.println("已经获得了连接");
                }
            }
        });
 
        //连接完成之前先等待
        latch.await();
        ZooKeeper.States states = zooKeeper.getState();
        System.out.println(states);
    }
}

public class ZkClientTest { 
    private static String ip = "192.168.0.101:2181"; 
    private static int  session_timeout = 40000; 
    public static void main(String[] args) {
        ZkClient zkClient = new ZkClient(ip,session_timeout);
        System.out.println(zkClient.getChildren("/"));
    }
}

 
public class CuratorDemo {  
    //ZooKeeper服务地址
    private static final String SERVER = "192.168.0.101:2181";
 
    //会话超时时间
    private static final int SESSION_TIMEOUT = 30000;
 
    //连接超时时间
    private static final int CONNECTION_TIMEOUT = 5000;
 
    /**
     * 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
     */
    private static final RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);  
    public static void main(String[] args) throws Exception {
        //创建 CuratorFrameworkImpl实例
        CuratorFramework client = CuratorFrameworkFactory.newClient(SERVER, SESSION_TIMEOUT, CONNECTION_TIMEOUT, retryPolicy);
 
        //启动
        client.start(); 
        System.out.println("连接成功！");
        Object o = client.getChildren().forPath("/");
        System.out.println(o);
    } 
}

public class ZookeeperBase{
	//zk集群地址(端口号为客户端端口号)
	private static final String CONNECT_ADDR = "192.168.241.127:2181,192.168.241.128:2181,192.168.241.129:2181";	
	//session 超时时间,单位毫秒
	private static final int SESSION_OUTTIME = 5000;	
	//用于阻塞程序执行，直到zk成功连接后再发送继续执行信号，因为zk建立连接是异步的，阻塞是防止程序在zk成功连接前被调用。
	private static final CountDownLatch contectedSemaphore = new CountDownLatch (1);	
	public static void main(String[] args)throws Exception{
		Zookeeper zk = new Zookeeper(CONNECT_ADDR,SESSION_OUTTIME,new Watcher()){
			@override
			public void process(WatcherEvent event){  //WatcherEvent为观察者监听事件
			
				//获取事件状态（与客户端连接状态相关）
				/*
				* KeeperState:Disconneced        连接失败 		 
				* KeeperState:SyncConnected	 连接成功	 		 
				* KeeperState:AuthFailed         认证失败		 
				* KeeperState:Expired            会话过期
				*/
				KeeperState keeperState = event.getState();
				
				//获取事件类型(与zknode相关)
				/*
				* EventType:NodeCreated            节点创建		 
				* EventType:NodeDataChanged        节点的数据变更		 
				* EventType:NodeChildrentChanged   子节点下的数据变更		 
				* EventType:NodeDeleted            节点删除
				* EventType:None                   刚连接什么都没做
				*/
				EventType eventType  = event.getType();
				
				//成功建立连接（固定写法）
				if(KeeperState.SyncConnected == keeperState){
					if(EventType.None == eventType){
						//发送信号让程序继续执行
						contectedSemaphore.countDown();
					}
				}				
			}
			
			//阻塞程序执行
			contectedSemaphore.await();
			//创建节点
			//同步创建
			String newNode = zk.create("/testRoot","data".getBytes(),ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);
			/*
			*参数1：节点路径：/testRoot,原生api不允许递归创建节点，即没有父节点不允许直接连带父子节点一起创建。创建节点是要写全路径，例如：/testRoot/children。
			*参数2：节点内容：内容类型为字节数组，不支持存储序列化对象，例如不支持将java对象序列化为json存储，但可以使用java序列化框架，如hession或kyso。
			*参数3：权限控制：在对权限要求不严格情况下都使用OPEN_ACL_UNSAFE开放权限即可。
			*参数4：节点类型：提供了四种类型。
			*PERSISTENT 持久化节点
			*PERSISTENT SEQUENTIAL 持久顺序节点
			*EPHEMERAL 临时节点
			*EPHEMERAL SEQUENTIAL 临时顺序节点
			*/
		};	
	} 	
}