Block servlet access to the file system or other Java core libraries in Jetty (like Google App Engine)?

GAE uses Jetty, and it preve开发者_StackOverflow中文版nts access to the file system from servlets.

I was wondering if limiting acces to core Java libraries from servlets can be accomplished in your own Jetty setup...is something like this done through configuring/customizing Jetty or is there a "servlet sandbox add-on" for Jetty?

I think that Jetty uses the standard Java security model, just like Tomcat.