This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Depends what you mean by "retrieve the file". You can certainly read the contents of the file. But if you want to know the name and location of a file, there doesn't seem to be any way to do that. If you really need to find the file name, and have no other way to do this, I suppose you could read in the contents, and then search the file system for a file with the same contents. (Similar to using grep or find in Unix.) But this is pretty ugly. I'd strongly recommend a redesign of some sort so you don't have to do this.