Spring AOP advice - conditional in debug mode

Question

I want to use the AOP advice/pointcuts, etc in debug mode only (as a master global config: e.g. when log4j is in DEBUG threshold).

How can I do this in the application.xml config or elsewhere?

I am using AOP annotations e.g.

@Around("PointCuts.anyCustomPublicMethod()")

public final Object logAdvice(final ProceedingJoinPoint pjp) throws Throwable {
...........
............

How to add to the advice something like,

debug.equals(TRUE)

I was told by someone to use Spring Expression Language, but I've no idea how to do it.