Field writer interceptor

Question

I'am studying Byte Buddy and I am trying to replace CGLib by it. I want to know if there is a way to implement to intercept writing to any field. I do not know the field type and I do not want to change the assigned value. I only want to log field written! on any access.

Example: if I have this class:

public class Ex {
    public int i;
    public String s;
    public boolean b;
}

later when I do this:

Ex e = new Ex();
e.i=1;
System.out.println("Value of i:" + i);
e.s="hello";
System.out.println("Value of s:" + hello);

it should output:

field written!
Value of i: 1
field writed!
Value of s: hello

In the help page under Custom Instrumentation, there is an example but it's not clear.

score 0 · Accepted Answer · edited May 23 '17 at 12:07

0

No, that is not possible. Is this something you were doing using cglib? Because this is neither possible using Byte Buddy nor using cglib.

The problem is that a field is not dispatched dynamically. Rather than redefining the class containing the field, you would need to redefine any class accessing the field what is close to impossible.

edited May 23 '17 at 12:07

Community

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answered May 03 '16 at 10:22

Rafael Winterhalter

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No. I could not implement that with CGLib. Today I have read ASM and now I understand that what I want is impossible. Tomorrow will try to rewrite my library with BB and see what happens. – Marcelo D. Ré May 04 '16 at 00:08

Field writer interceptor

1 Answers1