import java.util.List; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.Watcher.Event.EventType; import org.apache.zookeeper.Watcher.Event.KeeperState; import org.apache.zookeeper.ZooKeeper; import org.junit.Before; import org.junit.Test; public class ZookeeperWatchDemo { ZooKeeper zk = null; @Before public void init() throws Exception { // 构造一个连接zookeeper的客户端对象
        zk = new ZooKeeper("hdp-01:2181,hdp-02:2181,hdp-03:2181", 2000, new Watcher() { @Override public void process(WatchedEvent event) { //如果在连接，并且为该节点的数据变化了
                if (event.getState() == KeeperState.SyncConnected && event.getType() == EventType.NodeDataChanged) { System.out.println(event.getPath()); // 收到的事件所发生的节点路径
                    System.out.println(event.getType()); // 收到的事件的类型
                    System.out.println("数据变化了啊....."); // 收到事件后，我们的处理逻辑

                    try { zk.getData("/mygirls", true, null); } catch (KeeperException | InterruptedException e) { e.printStackTrace(); } //如果在连接，并且是字节点变化了
                }else if(event.getState() == KeeperState.SyncConnected && event.getType() == EventType.NodeChildrenChanged){ System.out.println("子节点变化了......"); } } }); } @Test public void testGetWatch() throws Exception { //此时监听的逻辑就是new ZooKeeper时的watcher，这里也可以自己写一个watcher， //但如果自己写的话，就会只运行一次了，不能重复监听
        byte[] data = zk.getData("/mygirls", true, null); // 监听节点数据变化
 List<String> children = zk.getChildren("/mygirls", true); //监听节点的子节点变化事件
 System.out.println(new String(data, "UTF-8")); //这时候启动的监听线程为一个守护线程，当主线程结束后，就会退出，所以这里让主线程睡眠时间，当主线程结束，他也就没了 //这个守护线程使我们在创建的zookeeper的时候就创建的，
 Thread.sleep(Long.MAX_VALUE); } }