Servlet Security

[Mazhar]

Hay; I am Working on some Java WebHosting Project. any body have any Idea how to restrict different servlets not to look in the underline directory structure. Means in servlets we can check the underline directory structure using simple Request and Response Object's methods. My Question is that how can i restrict any servlets while doing that. And Any Servlets Would Not be able to do any other operation of java.io.File Class.   Mazhar Saeed