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[java,zookeeper]2.1 KeeperState.SyncConnected linker

分类： Java

2015-06-28 16:29:47

1. Watcher1
自身实现 Watcher 接口，传入 this

点击(此处)折叠或打开

  1. package org.apache.zookeeper.demo;

  3. import java.util.concurrent.CountDownLatch ;


  6. import org.apache.zookeeper.WatchedEvent;
  7. import org.apache.zookeeper.Watcher;
  8. import org.apache.zookeeper.Watcher.Event.* ;
  9. import org.apache.zookeeper.ZooKeeper ;

  11. /**
  12.  * Created by root on 6/28/15.
  13.  */
  14. public class SyncConnect_Event_Tester implements Watcher // Watcher 1
  15. {
  16.     ZooKeeper zk = null ;
  17.  
  18.     final String CONNECTION_STRING = "127.0.0.1:2181" ;

  20.     final int SESSSION_TIMER = 2000 ;

  22.     private CountDownLatch connectedSemaphore = new CountDownLatch( 1 ) ;

  24.     public SyncConnect_Event_Tester ()
  25.     {
  26.         try
  27.         {

  29.             zk = new ZooKeeper ( CONNECTION_STRING , SESSSION_TIMER , this ) ;  
  30.             this.connectedSemaphore.await () ;
  31.         }
  32.         catch ( Exception e )
  33.         {
  34.             e.printStackTrace();
  35.         }
  36.     }

  38.     public void process ( WatchedEvent we )
  39.     {
  40.         try
  41.         {
  42.             Event.KeeperState keeperState = we.getState() ;

  44.             System.out.println (we.getState().toString()) ;

  46.             if (keeperState == Event.KeeperState.SyncConnected )
  47.             {
  48.                 System.out.println ("[Watche1] success connect to ZooKeeper Server ") ;

  50.                 connectedSemaphore.countDown();
  51.             }
  52.         }
  53.         catch ( Exception ex )
  54.         {

  56.         }
  57.     }


  60.     public static void main ( String [] args )
  61.     {
  62.         SyncConnect_Event_Tester tester = new SyncConnect_Event_Tester() ;
  63.     }
  64. }


2. Watcher2
另创建一个类实现 Watcher， 传入该类的实例对象

点击(此处)折叠或打开

  1. package org.apache.zookeeper.demo;

  3. import java.util.concurrent.CountDownLatch ;


  6. import org.apache.zookeeper.WatchedEvent;
  7. import org.apache.zookeeper.Watcher;
  8. import org.apache.zookeeper.Watcher.Event.* ;
  9. import org.apache.zookeeper.ZooKeeper ;

  11. /**
  12.  * Created by root on 6/28/15.
  13.  */
  14. public class SyncConnect_Event_Tester implements Watcher // Watcher 1
  15. {
  16.     ZooKeeper zk = null ;

  18.     final String CONNECTION_STRING = "127.0.0.1:2181" ;

  20.     final int SESSSION_TIMER = 2000 ;

  22.     private CountDownLatch connectedSemaphore = new CountDownLatch( 1 ) ;

  24.     public SyncConnect_Event_Tester ()
  25.     {
  26.         try
  27.         {

  29.             WatcherLoader w = new WatcherLoader( this.connectedSemaphore ) ;

  31.             zk = new ZooKeeper (CONNECTION_STRING , SESSSION_TIMER , w ) ; // this is for the Watcher 2
  32.             this.connectedSemaphore.await () ;
  33.          
  34.         }
  35.         catch ( Exception e )
  36.         {
  37.             e.printStackTrace();
  38.         }
  39.     }

  41.     public static void main ( String [] args )
  42.     {
  43.         SyncConnect_Event_Tester tester = new SyncConnect_Event_Tester() ;
  44.     }
  45. }

  47. class WatcherLoader implements Watcher
  48. {
  49.     private CountDownLatch countDownLatch ;

  51.     public WatcherLoader ( CountDownLatch countDownLatch )
  52.     {
  53.         this.countDownLatch = countDownLatch ;
  54.     }

  56.     public void process ( WatchedEvent e) {
  57.         try
  58.         {
  59.             Event.KeeperState keeperState = e.getState() ;

  61.             if (keeperState == Event.KeeperState.SyncConnected )
  62.             {
  63.                 System.out.println ("[Watche2] success connect to ZooKeeper Server ") ;
  64.                 countDownLatch.countDown();


  67.             }
  68.         }
  69.         catch ( Exception ex )
  70.         {
  71.             // ignore
  72.         }
  73.     }
  74. }

3. Watcher3

直接在 ZooKeeper 构造方法的 Watcher 参数中创建一个 Watcher 接口实例，并在 Watcher 内部编写 process 方法。

点击(此处)折叠或打开

  1. package org.apache.zookeeper.demo;

  3. import java.util.concurrent.CountDownLatch ;


  6. import org.apache.zookeeper.WatchedEvent;
  7. import org.apache.zookeeper.Watcher;
  8. import org.apache.zookeeper.Watcher.Event.* ;
  9. import org.apache.zookeeper.ZooKeeper ;

  11. /**
  12.  * Created by root on 6/28/15.
  13.  */

  15. public class SyncConnect_Event_Tester implements Watcher // Watcher 1
  16. {
  17.     ZooKeeper zk = null ;

  19.     final String CONNECTION_STRING = "127.0.0.1:2181" ;

  21.     final int SESSSION_TIMER = 2000 ;

  23.     private CountDownLatch connectedSemaphore = new CountDownLatch( 1 ) ;

  25.     public SyncConnect_Event_Tester ()
  26.     {
  27.         try
  28.         {
  29.             // this is for the Watcher 3
  30.             zk = new ZooKeeper ( CONNECTION_STRING , SESSSION_TIMER , new Watcher ()
  31.             {
  32.                 public void process ( WatchedEvent e )
  33.                 {
  34.                     try
  35.                     {
  36.                         Event.KeeperState keeperState = e.getState() ;

  38.                         if (keeperState == Event.KeeperState.SyncConnected )
  39.                         {
  40.                             System.out.println ("[Watche3] success connect to ZooKeeper Server ") ;
  41.                             connectedSemaphore.countDown();
  42.                         }
  43.                     }
  44.                     catch ( Exception ex )
  45.                     {
  46.                         // ignored
  47.                     }
  48.                 }
  49.             }) ;
  50.             this.connectedSemaphore.await () ;

  52.         }
  53.         catch ( Exception e )
  54.         {
  55.             e.printStackTrace();
  56.         }
  57.     }


  60.     public static void main ( String [] args )
  61.     {
  62.         SyncConnect_Event_Tester tester = new SyncConnect_Event_Tester() ;
  63.     }
  64. }


4. Watcher4
类似于第三种方法，创建 Watcher 实例，需要的时候将该实例传入到参数中.

点击(此处)折叠或打开

  1. package org.apache.zookeeper.demo;

  3. import java.util.concurrent.CountDownLatch ;


  6. import org.apache.zookeeper.WatchedEvent;
  7. import org.apache.zookeeper.Watcher;
  8. import org.apache.zookeeper.Watcher.Event.* ;
  9. import org.apache.zookeeper.ZooKeeper ;

  11. /**
  12.  * Created by root on 6/28/15.
  13.  */
  14. public class SyncConnect_Event_Tester implements Watcher // Watcher 1
  15. {
  16.     ZooKeeper zk = null ;

  18.     final String CONNECTION_STRING = "127.0.0.1:2181" ;

  20.     final int SESSSION_TIMER = 2000 ;

  22.     Watcher watcher ;

  24.     private CountDownLatch connectedSemaphore = new CountDownLatch( 1 ) ;

  26.     public SyncConnect_Event_Tester ()
  27.     {
  28.         try
  29.         {
  30.             // this is for the Watcher 4
  31.             this.watcher = new Watcher () {
  32.                 public void process(WatchedEvent e) {
  33.                     try
  34.                     {
  35.                         Event.KeeperState keeperState = e.getState() ;

  37.                         if (keeperState == Event.KeeperState.SyncConnected )
  38.                         {
  39.                             System.out.println ("[Watche4] success connect to ZooKeeper Server ") ;
  40.                             connectedSemaphore.countDown();
  41.                         }
  42.                     }
  43.                     catch ( Exception ex )
  44.                     {
  45.                         // ignored
  46.                     }
  47.                 }
  48.             } ;


  51.             zk = new ZooKeeper (CONNECTION_STRING, SESSSION_TIMER , this.watcher) ;

  53.             this.connectedSemaphore.await () ;


  56.         }
  57.         catch ( Exception e )
  58.         {
  59.             e.printStackTrace();
  60.         }
  61.     }

  63.     public static void main ( String [] args )
  64.     {
  65.         SyncConnect_Event_Tester tester = new SyncConnect_Event_Tester() ;
  66.     }
  67. }


end





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给主人留下些什么吧！~~

夏目玲子2015-06-28 17:07:48

正确的运行结果显示 Watcher1/2/3/4 如下:


[Watche4] success connect to ZooKeeper Server 

Process finished with exit code 0

其中，CountDownLatch  对象的作用是用作让主线程等待，直到回调函数的方法执行结束才能够让主线程退出。
如果不使用它，主线程跑完之后直接就退出了，而不会等待服务器连接成功，显示连接成功的信息之后才退出，
即，不使用无法看到 process 方法中的信息。

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