How to get login information?

[ucftcys]

I use DatabaseServerLoginModule to process the authentication.(with a form-based login page). How can I get the login name after login?thanks a lot..

[ucftcys]

I found the solution.
Principal pr = request.getUserPrincipal();
this will return the login name...however, it works in JSP..but not in servlet...in servlet it always return null..anyone knows why??