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Curator 异步获取结果
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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());