java.io.File诉org.apache.commons.vfs2.FileObject

Question

I'm trying to monitor a folder for a batch file that will be dropped there to make updates to a web app. The app already uses the Apache vfs2 library and I've been advised by my lead to use this as well.

My question is this: what is the conceptual difference between File in java.io and FileObject in org.apache.commons.vfs2?

I've read the docs at FileObject and File and what I'm really looking for is a conceptual distinction of these two classes. For example: is FileObject some kind of wrapper around File? I don't see much in common in their inheritance trees so it doesn't seem to me like FileObject is using File anywhere.

Answer 1

The VFS2 FileObject is an interface with no ties to a specific storage mechanism (this is the point of the VFS2 filesystem)

A FileObject can represent a local filesystem file, a file on an SFTP, FTP, HTTP or WebDav server, or a file inside a compressed archive, or any other thing you can think of that might hold a collection of bytes that make up a file.

java.io.File is a reference to a local file, and that's the end of it.

The benefit of the FileObject abstraction is that you can code to a single interface, and not care about where the bytes that make up that file actually come from (ie local filesystem, streamed via SFTP over SSH, via HTTP etc.)