is there a way to get the logged in user name (and group) from a Tomcat system. I read something about configuring Tomcat, so it is getting the user information out of a dat
You can try these two methods from the HttpServletRequest interface.
getUserPrincipal() returns a Principal from which you can get the logged used as getUserPrincipal().getName().
isUserInRole("Administrators") returns true if the current Principal is in the provided role.
Of course this only works if you are using tomcat realm authentication found here.
getUserPrincipal().getName()
There's a typo in above answer.