Using AspectJ to set the value of an annotated method parameter

Question

I imagine a method

public void fooMethod(Object param1, @SetupParam Object param2){
    // ... do stuff
}

That I want to call without the need of having to set param2

fooMethod("param1");

but having it magically setup in an advise. I am currently working with this code (simplified)

@Around("@annotation(com.example.SetupParam)")
public Object setupParam(ProceedingJoinPoint pjp) throws Throwable {
    Object[] args = pjp.getArgs();
    args[1] = "setup";
    return pjp.proceed(args);
}

but I need to call that method every time with

fooMethod("param1", null);

So I want to get rid of the null parameter. I am not using @Autowiring since the second parameter inside the method is always instantiated with different values.

Answer 1

I think Your pointcut definiition is wrong. What You need is @args definition with annotation inside. This matches methods whose arguments are annotated with defined annotation (as You described in question) your advice should look similar (haven't tested it) to

@Around("@args(.., com.example.SetupParam))")

note that .. means any number of arguments of any type.

Unfortunately, @args supports at most one .. wildcard , so as long as You decide on having those annotated arguments either at the start or at the end of your argument list, You should be fine.