Re: AspectJ modify property field content or add and/or change method body in a runtime instance

Jimmy wrote:


The method intercept should be doable using the around
technique in the previous example.

Accessing the private field requires reflection but it
can be facilitated by AspectJ.

Demo:

public class Dummy {
     public int v;
     public Dummy() {
         v = 123;
     }
     public String toString() {
         return "#" + v + "#";
     }
}

public interface Hack {
     public void setV(int v);
}

import java.lang.reflect.*;

public aspect HackImpl {
     declare parents: Dummy implements Hack;
     public void Hack.setV(int v) {
         try {
             Field field = getClass().getDeclaredField("v");
             field.setAccessible(true);
             field.setInt(this, v);
             } catch (NoSuchFieldException nsfe) {
                 nsfe.printStackTrace();
             } catch (IllegalAccessException iae) {
                 iae.printStackTrace();
             }
     }
}

public class Main {
     public static void main(String[] args) {
         Dummy o = new Dummy();
         System.out.println(o);
         ((Hack)o).setV(456);
         System.out.println(o);
     }
}

C:\>ajc Main.java Dummy.java Hack.java HackImpl.aj

C:\>java Main
#123#
#456#

Arne