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Curator Cache

时间:2016-05-12 10:34:51      阅读:287      评论:0      收藏:0      [点我收藏+]

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1.Curator Cache 与原生ZooKeeper Wacher区别

   原生的ZooKeeper Wacher是一次性的:一个Wacher一旦触发就会被移出,如果你想要反复使用Wacher,就要在Wacher被移除后重新注册,使用起来很麻烦。使用Curator Cache 可以反复使用Wacher了。

2.Curator Cache 和Curator Wacher区别

 

2.相关类

Curator Cache主要提供了一下三组类,分别用于实现对节点的监听,子节点的监听和二者的混合:

  1.NodeCache,NodeCacheListener,ChildData,节点创建,节点数据内容变更,不能监听节点删除。

  2.PathChildrenCache,PathChildrenCacheListener,PathChildrenCacheEvent监听指定节点的子节点的变更包括添加,删除,子节点数据数据变更这三类。

  3.TreeCache,TreeCacheListener,TreeCacheEvent,TreeCacheSelector

 

3.节点监听

package cn.francis.maven.hello.ZooKeeper;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.framework.recipes.cache.TreeCache;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.test.TestingServer;
import org.apache.curator.utils.CloseableUtils;
import org.apache.zookeeper.CreateMode;

public class NodeCacheDemo {
  public static void main(String[]args) throws Exception{
      TestingServer server=null;
      CuratorFramework client=null;
      NodeCache nodeCache=null;
      String path="/francis/nodecache/a";
      
     
      try{ 
         server=new TestingServer();
         client= CuratorFrameworkFactory.newClient(server.getConnectString(), new ExponentialBackoffRetry(1000,3));
         client.start();
         
         path=client.create().creatingParentsIfNeeded().withProtection().withMode(CreateMode.EPHEMERAL).forPath(path,"init".getBytes());
       
         
         nodeCache=new NodeCache(client,path,false);
         nodeCache.start();
         addListener(nodeCache);
         
         
        
         client.setData().forPath(path,"hello".getBytes());
         Thread.sleep(1000);
         client.delete().deletingChildrenIfNeeded().forPath(path);
         Thread.sleep(Integer.MAX_VALUE);
         
      }catch(Exception e){
          e.printStackTrace();
      }finally{
    
         
          //这里因为是测试,没有加他们。
          //CloseableUtils.closeQuietly(nodeCache);
         /// CloseableUtils.closeQuietly(client);
         // CloseableUtils.closeQuietly(server);
      }     
  }
  
  public static void addListener(NodeCache nodeCache){
      //监听类型:节点是否存在,节点数据内容改变,不监听节点删除。
         nodeCache.getListenable().addListener(new NodeCacheListener(){
    
            @Override
            public void nodeChanged() throws Exception {
                // TODO Auto-generated method stub
                if(nodeCache.getCurrentData()!=null)
                    System.out.println("path:"+nodeCache.getCurrentData().getPath()+",data:"+new String(nodeCache.getCurrentData().getData()));
                
            }});
  }
}

 

在上面的代码中首先创建了一个节点,然后创建用这个节点路径来创建NodeCache,启动NodeCache,添加NodeCacheListener。然后调用setData来修改节点数据。上面的代码输入如下:

path:/francis/nodecache/_c_d5be73ca-592c-4eda-b7c4-c8ec60ef39a8-a,data:hello

 

子节点监听:

 PathChildrenCache的构造函数如下:

public PathChildrenCache(CuratorFramework client,
                         String path,
                         boolean cacheData)
Parameters:
client - the client
path - path to watch
cacheData - if true, node contents are cached in addition to the stat

其中最主要的是cacheData,如果为true,那么当对子节点调用setData时,PathChildrenCache会受到这个CHILD_UPDATED事件。

下面看一下demo:

package cn.francis.maven.hello.ZooKeeper;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import org.apache.curator.framework.recipes.cache.TreeCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent.Type;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.test.TestingServer;
import org.apache.curator.utils.CloseableUtils;
import org.apache.curator.utils.ZKPaths;
import org.apache.hadoop.mapred.join.Parser.TType;
import org.apache.zookeeper.CreateMode;

public class NodeCacheDemo {
  public static void main(String[]args) throws Exception{
      TestingServer server=null;
      CuratorFramework client=null;
      NodeCache nodeCache=null;
      String path="/francis/nodecache/b";
      
     
      try{ 
         server=new TestingServer();
         client= CuratorFrameworkFactory.newClient(server.getConnectString(),new ExponentialBackoffRetry(1000,3));
         client.start();
         
         //这里将第三个参数cacheData设置为true,这样当对子节点调用setData时,会受到CHILDREN_UPDATE通知。
         PathChildrenCache childrenCache=new PathChildrenCache(client,path,true);
         
childrenCache.start(StartMode.POST_INITIALIZED_EVENT); childrenCache.getListenable().addListener(
new PathChildrenCacheListener(){ @Override public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception { // TODO Auto-generated method stub if(event.getType()==Type.INITIALIZED){ System.out.println("create"+event.getData().getPath()); }else if(event.getType()==Type.CHILD_ADDED){ System.out.println("create"+event.getData().getPath()); }else if(event.getType()==Type.CHILD_REMOVED){ System.out.println("remove:"+event.getData().getPath()); }else if(event.getType()==Type.CHILD_UPDATED){ //System.out.println("update:"+event.getData().getPath()); System.out.println("update:"+new String(event.getData().getData())); } }}); //创建父节点 System.out.println(client.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path,"init".getBytes())); Thread.sleep(1000); //创建子节点 String childPath1=ZKPaths.makePath(path, "a"); childPath1=client.create().withMode(CreateMode.PERSISTENT).forPath(childPath1,"1".getBytes()); Thread.sleep(1000); //对子节点赋值 client.setData().forPath(childPath1,"aaa".getBytes()); Thread.sleep(1000); //删除子节点 client.delete().forPath(childPath1); client.delete().deletingChildrenIfNeeded().forPath("/francis"); Thread.sleep(2000); }catch(Exception e){ e.printStackTrace(); }finally{ CloseableUtils.closeQuietly(nodeCache); CloseableUtils.closeQuietly(client); CloseableUtils.closeQuietly(server); } }

 

 

3.TreeNodeCache

   TreeNodeCache将NodeCache和PathChildrenCache功能结合到一起了。他不仅可以对子节点和父节点同时进行监听。如下:

 

package cn.francis.maven.hello.ZooKeeper;

import java.util.Map;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.framework.recipes.cache.ChildData;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import org.apache.curator.framework.recipes.cache.TreeCache;
import org.apache.curator.framework.recipes.cache.TreeCacheEvent;
import org.apache.curator.framework.recipes.cache.TreeCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent.Type;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.test.TestingServer;
import org.apache.curator.utils.CloseableUtils;
import org.apache.curator.utils.ZKPaths;
import org.apache.hadoop.mapred.join.Parser.TType;
import org.apache.zookeeper.CreateMode;

public class NodeCacheDemo {
  public static void main(String[]args) throws Exception{
      TestingServer server=null;
      CuratorFramework client=null;
      NodeCache nodeCache=null;
      String path="/francis/nodecache/b";
      
     
      try{ 
         server=new TestingServer();
         client= CuratorFrameworkFactory.newClient(server.getConnectString(),new ExponentialBackoffRetry(1000,3));
         client.start();
         
    
         TreeCache treeNodeCache=new TreeCache(client,path);
         
         treeNodeCache.start();
         
         treeNodeCache.getListenable().addListener(new TreeCacheListener(){

            @Override
            public void childEvent(CuratorFramework client, TreeCacheEvent event) throws Exception {
                // TODO Auto-generated method stub
                switch(event.getType()){
                  case NODE_ADDED:
                      System.out.println("added:"+event.getData().getPath());
                      break;
                  case NODE_UPDATED:
                      System.out.println("updated:"+event.getData().getPath());
                      break;
                  case NODE_REMOVED: 
                      System.out.println("removed:"+event.getData().getPath());
                      break;
                  default:
                      System.out.println("other:"+event.getType());
                }
           }
             
         });
         
         

         
         //创建父节点
         client.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path,"init".getBytes());
         Thread.sleep(1000);
         
         //创建子节点
         String childPath1=ZKPaths.makePath(path, "a");
         childPath1=client.create().withMode(CreateMode.PERSISTENT).forPath(childPath1,"1".getBytes());
         Thread.sleep(1000);
         
         //对子节点赋值
         client.setData().forPath(childPath1,"aaa".getBytes());
         Thread.sleep(1000);

         //对子节点赋值
         client.setData().forPath(path,"aaa".getBytes());
         Thread.sleep(1000);

         //删除子节点
         client.delete().forPath(childPath1);
         client.delete().deletingChildrenIfNeeded().forPath("/francis");
         
        
         Thread.sleep(2000);
         
      }catch(Exception e){
          e.printStackTrace();
      }finally{
    
         
          //这里因为是测试,没有加他们。
          CloseableUtils.closeQuietly(nodeCache);
          CloseableUtils.closeQuietly(client);
          CloseableUtils.closeQuietly(server);
      }     
  }
}

 

输出如下:

other:INITIALIZED
added:/francis/nodecache/b
added:/francis/nodecache/b/a
updated:/francis/nodecache/b/a
updated:/francis/nodecache/b
removed:/francis/nodecache/b/a
removed:/francis/nodecache/b

Curator Cache

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原文地址:http://www.cnblogs.com/francisYoung/p/5483777.html

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