This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Depends what you want to do. If you want to write/edit files, it is not so easy. If you are looking to read from a file, you can (usually) use the ClassLoader to find an InputStream from files in the WAR/EAR