http://www.onjava.com/pub/a/onjava/2004/07/21/insidebox2.html

and does not mention APT, unfortunately.

APT appears to be very similar to the bytecode instrumentation framework that I wrote as part of this article, but focuses entirely on source code instrumentation. This is a topic that I just glossed over in the article because of a lack of tools to help simplify this. This is exactly what I was looking for at the time. I've also since discovered Apache Velocity, which is a tool for the creation of files from templates. It may also be worth investigating the use of Velocity if you want to do this type of programming but feel a bit uneasy about bytecode instrumentation.