How to get Role and Password from JDBC Realm

[me...@twrichter.de]

Hello,

I want to use the provided user_pass and user_role in the
JDBCRealm-Database given in server.xml. What is the most elegant way to do
this? Of cource I would be able to get it via request.getRemoteUser() and
then make a select to the hardcoded database name with provided auth user
and pass like it is given in server.xml. But there must be a better way
since database name, username and driver url is already included in the
Realm section? How to use it? I read the JDBCRealm code but I did not find
out where it gets the connectionUrl a.s.o.

Best Regards
   Thomas