Owncloud如何知道是否上传了新文件？

I'm working on an Owncloud app, but I am wondering how Owncloud knows if a new file is uploaded. Can someone point it out?

You're not too clear on what exactly you want to achieve, but to me it sounds like you want your app to get notified whenever a new file is uploaded, is that right?

Then you should take a look at filesystem hooks - preCreate or postCreate is probably for you depending on when you want to react...