并发技术CountDownLatch的使用

1.点击zkServer.cmd启动zookeeper服务，点击zkCli.cmd启动zookeeper客户端

2.下载ZooInspector，界面化管理zookeeper

3.解压，点击zookeeper-dev-ZooInspector.jar进入界面管理

4.点击绿色的启动按钮输入端口号启动

5.打开界面如图

6.在连接zookeepr中使用CountDownLatch并发控制，首先注释掉CountDownLatch，运行程序

package com.itmayiedu.test001;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import org.apache.zookeeper.CreateMode;
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.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
/**   
 * @ClassName:     Test001   
 * @Description:  java操作zk 
 * @author:        Taurus
 * @date:          2018年3月21日 下午7:42:24     
 */
public class Test001 {


//zk连接地址
private static final String CONNECTSTRING="127.0.0.1:2181";
//Zk会话超时时间
private static final int SESSION_OUTTIME=2000;
//使用countDownLatch  阻塞用户程序 用户必须等待连接  发送成功信号
//private static final CountDownLatch countdownLatch =new CountDownLatch(1);
public static void main(String[] args) throws IOException, KeeperException, InterruptedException {
ZooKeeper zk = new ZooKeeper(CONNECTSTRING,SESSION_OUTTIME,new Watcher(){
            //事件通知
public void process(WatchedEvent event) {
// TODO Auto-generated method stub
//获取事件状态
KeeperState keeperState = event.getState();
//判断为连接状态
if(KeeperState.SyncConnected==keeperState){
//获取到事件类型
EventType eventType=event.getType();
if(eventType==EventType.None){
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//事件为连接状态
// countdownLatch.countDown();
System.out.println("#######zk开始启动连接#########");
}
}
}
});
//countdownLatch.countDown为0，不阻塞
// countdownLatch.await();
//创建为持久类型，节点开放权限
   String result = zk.create("/itmayiedu_lasting1", "lasting1".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
System.out.println("##########新增节点信息###########"+result);
zk.close();
}

}

运行结果：我们可以看到初始化zookeeper还没有运行完就创建完成了，显然这是多线程的，我们怎么解决这样的问题呢，

开启CountDownLatch再启动，问题解决

同时zookeeper界面管理页面也增加了两个节点