This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
You will need to use the security manager; see the Security Features in Java SE tutorial to start with. This is how applets are prevented from accessing local files, and from using reflection to get around these limits.