通知机制程序代码_java培训

1.程序代码

• 一次性

package com.atguigu.zk3;

import java.io.IOException;

import org.apache.log4j.Logger;

import org.apache.zookeeper.CreateMode;

import org.apache.zookeeper.KeeperException;

import org.apache.zookeeper.WatchedEvent;

import org.apache.zookeeper.Watcher;

import org.apache.zookeeper.ZooKeeper;

import org.apache.zookeeper.ZooDefs.Ids;

import org.apache.zookeeper.data.Stat;

public class WatchOne

{

   /**

   * Logger for this class

   */

   private static final Logger logger = Logger.getLogger(HelloZK.class);

   //定义常量

   private static final String CONNECTSTRING = “192.168.67.167:2181”;

   private static final String PATH = “/atguigu”;

   private static final int    SESSION_TIMEOUT = 50*1000;

   //定义实例变量

   private ZooKeeper zk = null;

   //以下为业务方法

   public ZooKeeper startZK() throws IOException

   {

       return new ZooKeeper(CONNECTSTRING, SESSION_TIMEOUT, new Watcher() {

          @Override

          public void process(WatchedEvent event)

          {

          }

       });

   }

   public void stopZK() throws InterruptedException

   {

       if(zk != null)

       {

          zk.close();

       }

   }

   public void createZNode(String path,String nodeValue) throws KeeperException, InterruptedException

   {

       zk.create(path,nodeValue.getBytes(),Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);

   }

   public String getZNode(String path) throws KeeperException, InterruptedException

   {

       byte[] byteArray = zk.getData(path,new Watcher() {

          @Override

          public void process(WatchedEvent event)

          {

              try

              {

                 triggerValue(path);

              }catch (KeeperException | InterruptedException e) {

                 e.printStackTrace();

              }

          }

       }, new Stat());

       return new String(byteArray);

   }

   public String triggerValue(String path) throws KeeperException, InterruptedException

   {

       byte[] byteArray = zk.getData(path,false, new Stat());

       String retValue = new String(byteArray);

       System.out.println(“**************triggerValue: “+retValue);

       return retValue;

   }

   public static void main(String[] args) throws IOException, KeeperException, InterruptedException

   {

       WatchOne watchOne = new WatchOne();

       watchOne.setZk(watchOne.startZK());

       if(watchOne.getZk().exists(PATH, false) == null)

       {

          watchOne.createZNode(PATH,”BBB”);

          System.out.println(“**********************>: “+watchOne.getZNode(PATH));

          Thread.sleep(Long.MAX_VALUE);

       }else{

          System.out.println(“i have znode”);

       }

   }

   //setter—getter

   public ZooKeeper getZk()

   {

       return zk;

   }

   public void setZk(ZooKeeper zk)

   {

       this.zk = zk;

   } 

}

• 多次

package com.atguigu.zk3;

import java.io.IOException;

import org.apache.log4j.Logger;

import org.apache.zookeeper.CreateMode;

import org.apache.zookeeper.KeeperException;

import org.apache.zookeeper.WatchedEvent;

import org.apache.zookeeper.Watcher;

import org.apache.zookeeper.ZooKeeper;

import org.apache.zookeeper.ZooDefs.Ids;

import org.apache.zookeeper.data.Stat;

public class WatchMoreTest

{

   /**

   * Logger for this class

   */

   private static final Logger logger = Logger.getLogger(WatchMoreTest.class);

   //定义常量

   private static final String CONNECTSTRING = “192.168.67.167:2181”;

   private static final String PATH = “/atguigu”;

   private static final int    SESSION_TIMEOUT = 50*1000;

   //定义实例变量

   private ZooKeeper zk = null;

   private String lastValue = “”;

   //以下为业务方法

   public ZooKeeper startZK() throws IOException

   {

       return new ZooKeeper(CONNECTSTRING, SESSION_TIMEOUT, new Watcher() {

          @Override

          public void process(WatchedEvent event)

          {}

       });

   }

   public void stopZK() throws InterruptedException

   {

       if(zk != null)

       {

          zk.close();

       }

   }

   public void createZNode(String path,String nodeValue) throws KeeperException, InterruptedException

   {

       zk.create(path,nodeValue.getBytes(),Ids.OPEN_ACL_UNSAFE,CreateMode.PERSISTENT);

   }

   public String getZNode(String path) throws KeeperException, InterruptedException

   {

       byte[] byteArray = zk.getData(path,new Watcher() {

          @Override

          public void process(WatchedEvent event)

          {

              try

              {

                 triggerValue(path);

              }catch (KeeperException | InterruptedException e) {

                 e.printStackTrace();

              }

          }

       }, new Stat());

       return new String(byteArray);

   }

   public boolean triggerValue(String path) throws KeeperException, InterruptedException

   {

       byte[] byteArray = zk.getData(path,new Watcher() {

          @Override

          public void process(WatchedEvent event)

          {

              try

              {

                 triggerValue(path);

              }catch (KeeperException | InterruptedException e) {

                 e.printStackTrace();

              }

          }

       }, new Stat());

       String newValue = new String(byteArray);

       if(lastValue.equals(newValue))

       {

          System.out.println(“there is no change~~~~~~~~”);

          return false;

       }else{

          System.out.println(“lastValue: “+lastValue+”\t”+”newValue: “+newValue);

          this.lastValue = newValue;

          return true;

       }

   }

   public static void main(String[] args) throws IOException, KeeperException, InterruptedException

   {

       WatchMoreTest watch = new WatchMoreTest();

       watch.setZk(watch.startZK());

       if(watch.getZk().exists(PATH, false) == null)

       {

          String initValue = “0000”;

          watch.setLastValue(initValue);

          watch.createZNode(PATH,initValue);

          System.out.println(“**********************>: “+watch.getZNode(PATH));

          Thread.sleep(Long.MAX_VALUE);

       }else{

          System.out.println(“i have znode”);

       }

   }

   //setter—getter

   public ZooKeeper getZk()

   {

       return zk;

   }

   public void setZk(ZooKeeper zk)

   {

       this.zk = zk;

   }

   public String getLastValue()

   {

       return lastValue;

   }

   public void setLastValue(String lastValue)

   {

       this.lastValue = lastValue;

   } 

}