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原声的ZooKeeper 的CRUD API有同步和异步之分，对于异步API，需要传递AsyncCallback回调。对于getData,getChildren，exists这三个API，还可以设置Watcher。这些功能在Curator中是如何实现的？
在Curator中，可以通过如下三种方式来异步获取结果：
1.inBackground()+CuratorListener
2.inBackground(new BackgroundCallback(){ public void processResult(CuratorFramework client,CuratorEvent event){}})
3.inBackground(newBackgroundCallback(){},Executor)
以inBackground()+CuratorListener这种方式来使用异步API，如下：
client.getCuratorListenable().addListener(new CuratorListener(){ @Override public void eventReceived(CuratorFramework client, CuratorEvent event) throws Exception { // TODO Auto-generated method stub if(event.getType()==CuratorEventType.CREATE){ System.out.println("create path="+event.getPath()+",code="+event.getResultCode()); }else if(event.getType()==CuratorEventType.GET_DATA){ System.out.println("get path="+event.getPath()+",data="+new String(event.getData())); }else if(event.getType()==CuratorEventType.SET_DATA){ System.out.println("set path="+event.getPath()+",data="+new String(client.getData().forPath(event.getPath()))/*+",data="+new String(event.getData())*/); }else if(event.getType()==CuratorEventType.DELETE){ System.out.println("delete path="+event.getPath()); } }});
接下来client的所有以inBackground()方式使用的API，其异步处理结果都是通过这个CuratorListener来处理。
在第二中方式inBackground(BackgroundCallback)中，如下：
client.create() .creatingParentsIfNeeded() .withProtection() .withMode(CreateMode.EPHEMERAL) .inBackground(new BackgroundCallback(){ @Override public void processResult(CuratorFramework client, CuratorEvent event) throws Exception { // TODO Auto-generated method stub if(event.getType()==CuratorEventType.CREATE){ System.out.println("code:"+event.getResultCode()+"path:"+event.getPath()); //client.getData().inBackground().forPath(event.getPath()); } } } ) .forPath("/francis/tmp/a","wbs".getBytes());
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原文地址：http://www.cnblogs.com/francisYoung/p/5458615.html
