This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara 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