分布式助手Zookeeper（七） - 三劫散仙

/***
 * @author qin dong liang
 * 
 * */
public class LockUnFair3  implements Watcher {
	
	
	/**
	 * ZK实例
	 * */
	private ZooKeeper zk;
	
	/**原子计数锁，防止在zk没有连上前，执行CURD操作*/
	private CountDownLatch down=new CountDownLatch(1);
	
	public LockUnFair3() {
		// TODO Auto-generated constructor stub
	}
	
	
	
	public LockUnFair3(String host)throws Exception {
		 this.zk=new ZooKeeper(host, 5000	, new Watcher() {
			
			@Override
			public void process(WatchedEvent event) {
				// TODO Auto-generated method stub
				/**链接上zk服务，岂可取消阻塞计数**/
				if(event.getState()==KeeperState.SyncConnected){
					down.countDown();
				}
				
			}
		});
	}
	/**
	 * 字符编码
	 * 
	 * **/
	 private static final Charset CHARSET=StandardCharsets.UTF_8;
	 
	@Override
	public void process(WatchedEvent event) {
		// TODO Auto-generated method stub
		 
		if(event.getType()==Event.EventType.NodeDeleted){
			
			//如果发现，监听的节点，挂掉了，那么就重新，进行监听 
			try{
		  // System.out.println("注意有锁退出或释放，公平锁开始抢占........");
				System.out.println("3我可以去抢占了");
				createTemp();
		//	check();
			}catch(Exception e){
				e.printStackTrace();
				
			}
		}
	}
	 
	 SimpleDateFormat f=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

	 
	  /**
	   * 关闭zk连接
	   * 
	   * **/
	 public void close()throws Exception{
		 zk.close();
	 }
	  
	 Random random=new Random();
	 /***
	  * 创建锁node，注意是抢占 的
	  * 
	  * 
	  * */
	 public void createTemp()throws Exception{
	 
		
		 Thread.sleep(random.nextInt(2500));//加个线程休眠，实现模拟同步功能
		 
	   if(zk.exists("/a/b", this) != null){
		   System.out.println("锁被占用,监听进行中......");
	   }else{
		   
		   
		   
		  String data=zk.create("/a/b", "a".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
		  System.out.println("Lock3创建锁成功，节点路径:    " data);
		  
	   }
		 
		// System.out.println("2" data);
		 
	 }
	 
	public static void main(String[] args)throws Exception {
			
			//Slave s=new Slave("192.168.120.128:2181");
			LockUnFair3 lock=new LockUnFair3("192.168.120.128:2181");
		    //  lock.createPersist();//创建主节点
			 lock.createTemp();
			// lock.check();
			  Thread.sleep(Long.MAX_VALUE);
			 lock.close();
			
	}
	 
	 
	 
}