Java Reflection: Find method usage in custom AbstractProcessor

Question

I'm newbie in reflection. Is there any way to detect where is an specific method invoked? For example:

public class MyClass {

   public static void method(){ 
       //DO SOMETHING
   }

}

public class Test {

    public test(){
       MyClass.method();
    }

}

public class MyProcessor extends AbstractProcessor {

   public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {

      Method method = MyClass.class.getDeclaredMethod("method");

      Class classWhereMethodIsInvoked = obtainClassWhereMethodIsInvoked(method); 

   }

   public Class obtainClassWhereMethodIsInvoked(Method method) {
      //here I want to search one class that invoke that method, in this case Test.class
   }

}

is something like this possible or I am going crazy?

Answer 1

As mentioned in the comments, Apache BCEL is suitable for your problem. Such libraries are often particularly used for determining compile-time information such as method usage and control flow analysis from the generated bytecode, and such information are difficult, if not impossible, to retrieve using reflection. If you use the BCEL solution, you probably no longer require a custom annotation processor.

But since you already seem to be using a custom annotation processor, the whole point of it is to be able to process annotations in the source files. So one way is to define a custom annotation that marks a method being called, and have the custom processor read these annotations to know which classes call which methods:

@CallerClass("MyClass.method")
public class Test {

    public test() {
       MyClass.method();
    }

} 

In the above (trivial) example, a custom CallerClass annotation marks that a class calls the method specified in the annotation's element inside parentheses. The annotation processor can read this annotation and construct the caller information.