Hi,
Please read
this.. As per this, the real path returns you the absolute path and it depends on the computer and also the container.
The issue which you have is due to the way
JBoss is handling the deployment. You may need to refer JBoss documentation or move this to JBoss forum, for better answer.
I tried the example on both JBoss and GlassFish and I see the problem in JBoss but not on Glassfish.