Don't.
You should NEVER upload files to locations inside of a WAR. Aside from the fact that it will produce major headaches, it's technically a violation of the
J2EE spec despite being physically possible in some (but not all) webapp servers (depending on how they're configured).
Designate a dedicated upload directory that's outside of both the webapp AND the
Tomcat server directory trees and use that. I normally make that directory path be a configurable option, but that's just for flexibility. The important thing is that the upload directory should not be inside the deployed WAR.