Comments on: Virtual filesystem

By: Noroi

Noroi — Tue, 20 Sep 2011 17:17:20 +0000

I would like to know how to create a virtual file system using java. Please comment…..

By: Chris Clark

Chris Clark — Thu, 13 Nov 2008 10:50:31 +0000

It’s a bit painful (to say the least), but you can use the Java instrumentation API (http://java.sun.com/j2se/1.5.0/docs/api/java/lang/instrument/package-summary.html) to reinstrument the classes that handle IO (for example FileInputStream/FileOutputStream/File/FileReader/FileWriter/etc…) to use a class that implements the same api, but supports an in-memory file system by using an alternate base directory, e.g. ‘/in-memory/’.

But I do admit that the new JSR is a better alternative, as long as the current IO and NIO packages are reengineered to use it in the background (otherwise implementing an in-memory FS would be a pain if you have code which uses the old IO APIs – you would have to rewrite all the code to use the new APIs just to be able to use an in-memory FS).

By: Bob McWhirter

Bob McWhirter — Wed, 12 Nov 2008 02:33:02 +0000

There’s the JBoss Microcontainer VFS project:

MC site: http://www.jboss.org/jbossmc/

VFS code: http://anonsvn.jboss.org/repos/jbossas/projects/vfs/trunk/

You can use VFS without the whole container, easily enough.

By: Alan

Alan — Tue, 11 Nov 2008 16:27:08 +0000

It would be good to include a good memory file system implementation. If someone has the cycles to do this and contribute it that would be great. I agree it would be useful from an educational perspective. It may also be useful when running on operating systems that don’t have /tmp or equivalent on swap. In the demo directory there is a read-only zip/JAR provider (contributed by Rajendra Gutupalli).

By: Alex

Alex — Tue, 11 Nov 2008 15:25:37 +0000

Good comments all. I can also see filesystems for zip/jar archives, storage in the cloud, and other such useful impls.