Zookeeper客户端API之读取子节点列表（八）

/**
 * 返回指定路径下面的子节点列表。
 * 如果watcher不为null，并且调用成功（没有异常），会将watcher注册在指定的path
 * 上。当path（父节点）被删除或者path下面创建/删除子节点，将触发通知watcher。
 * 
 * 返回结果列表不保证有序性。
 */
public List<String> getChildren(final String path, Watcher watcher)

/**
 * 使用说明同上一个方法。
 */
public List<String> getChildren(String path, boolean watch)

/**
 * getChildren(String, Watcher)的异步版本
 */
public void getChildren(final String path, Watcher watcher,
            ChildrenCallback cb, Object ctx)

/**
 * getChildren(String, boolean)的异步版本
 */
public void getChildren(String path, boolean watch, ChildrenCallback cb,
            Object ctx)

/**
 * 为指定的路径返回stat和子节点列表。
 * 
 */
public List<String> getChildren(final String path, Watcher watcher,
            Stat stat)

/**
 * 使用说明同上一个方法。
 */
public List<String> getChildren(String path, boolean watch, Stat stat)

/**
 * getChildren(String, Watcher, Stat)的异步版本
 */
public void getChildren(final String path, Watcher watcher,
            Children2Callback cb, Object ctx)

/**
 * getChildren(String, boolean, Stat)的异步版本
 */
public void getChildren(String path, boolean watch, Children2Callback cb,
            Object ctx)

package com.secbro.learn;

import org.apache.zookeeper.*;

import java.util.List;
import java.util.concurrent.CountDownLatch;

/**
 * 获得子节点列表的方法
 * Created by zhuzs on 2017/3/26.
 */
public class TestGetChildrenMethod implements Watcher {

    private static CountDownLatch countDownLatch = new CountDownLatch(1);

    private static ZooKeeper zooKeeper;
    public static void main(String[] args) throws Exception {
        zooKeeper = new ZooKeeper("127.0.0.1:2181", 5000, new TestGetChildrenMethod());
        countDownLatch.await();

        // 创建父节点/test
        zooKeeper.create("/test", "123".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
        // 在父节点/test下面创建a1节点
        zooKeeper.create("/test/a1", "456".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

        // 同步获得结果
        List<String> childrenList = zooKeeper.getChildren("/test", true);
        System.out.println("同步getChildren获得数据结果：" + childrenList);

        // 异步获得结果
        zooKeeper.getChildren("/test",true,new MyChildren2Callback(),null);

        // 在父节点/test下面创建a2节点
        zooKeeper.create("/test/a2", "456".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);

        Thread.sleep(10000);

    }

    public void process(WatchedEvent event) {
        if (Event.KeeperState.SyncConnected == event.getState()) {
            if(Event.EventType.None == event.getType() && null == event.getPath()){ // 连接时的监听事件
                countDownLatch.countDown();
            } else if (event.getType() == Event.EventType.NodeChildrenChanged){ // 子节点变更时的监听
                try {
                    System.out.println("重新获得Children，并注册监听：" + zooKeeper.getChildren(event.getPath(),true));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}
class MyChildren2Callback implements AsyncCallback.Children2Callback{

    public void processResult(int rc, String path, Object ctx, List<String> children, Stat stat) {
        System.out.println("异步获得getChildren结果，rc=" + rc
                + "；path=" + path + "；ctx=" + ctx + "；children=" + children +"；stat=" + stat);
    }
}

同步getChildren获得数据结果：[a1]
异步获得getChildren结果，rc=0；path=/test；ctx=null；children=[a1]；stat=14277,14277,1490498559704,1490498559704,0,1,0,0,3,1,14278

重新获得Children，并注册监听：[a1, a2]