If you are interested in using FreeRadius on MySQL start at
http://www.frontios.com/freeradius.html
get more information plus a copy at
http://www.freeradius.org/development.html
OR if you want to ftp the server
ftp://ftp.freeradius.org/pub/radius/freeradius.tar.gz
For FreeRadius and Java, there's s really cool tool for developers (gives you APIs and stuff). Find out about the Open Source Java program JRadius at
http://jradius.sourceforge.net/ AND check out the developer's notes so U don't mess Urself up