[大数据]zookeeper模拟监听节点变化（Java实现）

本地安装zookeeper后使用命令创建好节点以便测试：

create /mydata A1

下面就可以开始实验了，我们直接来看代码：

package com.itstyle.seckill.zookeeper;

import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;

import java.util.concurrent.CountDownLatch;

public class zkTest implements Watcher {

    //生成一个线程计数器，用来当作阀门控制
    private static CountDownLatch countDownLatch=new CountDownLatch(1);
    private static ZooKeeper zk=null;
    private static Stat stat=new Stat();

    public static void main(String[] args) throws Exception {
        String path = "/mydata";
        System.out.println("---1---");
        zk = new ZooKeeper("127.0.0.1:2181",5000,new zkTest());
        countDownLatch.await();
        System.out.println("---4---");

        //根据节点进行监听
        byte[] data = zk.getData(path, true, stat);

        String strData=new String(data);
        System.out.println("--------原始数据："+strData);

        //睡眠最大时间，以便一直进行监听
        Thread.sleep(Integer.MAX_VALUE);

    }

    public void process(WatchedEvent watchedEvent) {
        System.out.println("---2---");
        String path = "/mydata";
        if(Event.KeeperState.SyncConnected==watchedEvent.getState()){//连接成功
            //计数器减一，让上面的监听countDownLatch.await()后面代码继续执行
            if(Event.EventType.None==watchedEvent.getType()&& null==watchedEvent.getPath()){
                countDownLatch.countDown();
            }else if(Event.EventType.NodeDataChanged==watchedEvent.getType()){
                //根据节点进行监听
                byte[] data = new byte[0];
                try {
                    data = zk.getData(path, true, stat);
                    String s = new String(data);
                    System.out.println("节点数据有变化："+s);
                } catch (KeeperException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
        }

        System.out.println("---3---");
    }
}

#初始化的打印
---1---

---2---
---3---
---4---

--------原始数据：m4

#节点变化后的打印

---2---

节点数据有变化：m5
---3---