Executing a method, when any other method in that class is called other then Aspect

Question

I am looking for java implementation where a method gets executed , when any other method in that class is called other then Aspect (Something like what @before does for Junits)

I prefer not using JAspect. (Just because i dont want to have a Spring config file, if its possible without a Spring XML config )

Simple Example

public class Reader {

    private void init(){}

    private void method1(){}

    private void method2(){}

}

Here every time method1 or method2 is called , it has to call init().

1. I am not interested to call init() inside that method.
2. I am not interested to use Aspect with XML config.

Thanks in advance

Answer 1

You can try to adapt your implementation using Javassist . You can find a good introduction here . The following code snippet is taken from the tutorial (slightly adapted) and shows how you can manipulate the bytecode to insert additional commands:

public class Hello {
    public void say() {
        System.out.println("Hello");
    }

    public void ask() {
        System.out.println("HM?");
    }
}

public class Test {
    public static void main(String[] args) throws Exception {
        ClassPool cp = ClassPool.getDefault();
        CtClass cc = cp.get("Hello");
        CtMethod m = cc.getDeclaredMethod("say");
        m.insertBefore("{ ask(); }");
        Class c = cc.toClass();
        Hello h = (Hello)c.newInstance();
        h.say();
    }
}

Answer 2

You should have a look at the Proxy-Pattern.

JAVA already provides this mechanism. It is called dynamic proxy.

Check out this: http://tutorials.jenkov.com/java-reflection/dynamic-proxies.html

Or search for "JAVA dynamic proxies". You will find tons of resources.

Some theory: There are three possibilities to do as you wish:

1. Aspect orientation (you do not want to)
2. Template method-Pattern (you do not want to)
3. Proxy pattern (the only one left)