[SOLVED] Byte Buddy Advice Custom Object

Byte Buddy Advice Custom Object

I'm trying to use byte buddy and I appreciate your help for the below: Given that I have the following class

public class MyAdvice {
    private String param1;
    private Object param2;

    public MyAdvice(String param1, Object param2) {
        this.param1 = param1;
        this.param2 = param2;
    }
}

I want to pass this to my interceptor, is this possible? I've read about binding the value to an annotation I think I am missing someting, as I was only able to make it work with String class

MyAdvice[] myAdvice = new MyAdvice[1];
myAdvice[0] = new MyAdvice("123", new Object());
builder.method(ElementMatchers.named(setterMethodName)
       .and(ElementMatchers.takesArguments(1)))
       .intercept(Advice.withCustomMapping()
       .bind(Custom.class, myAdvice)
       .to(SetterInterceptor.class))

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface Custom { }

public class SetterInterceptor {
    public static void intercept(@Argument(0) Object value @Custom MyAdvice[] myAdvice) {
        // custom code, do something with myAdvice
    }
}

Is something like this possible?

@Custom MyAdvice[] myAdvice

Solution

In theory, any serializable value can be assigned to an annotated parameter. However, values would loose identity, such as your new Object(). It is however rarely recommended to do this, I would rather create a custom StackManipulation that creates the relevant values.

If applicable, you can also add a field to the instrumented class and define a fixed value as the field's value. This would preserve the identity, but alter the field.

As a last option, you can define a carrier class where you store the values in some map that is globally available. The you could create some random string like a UUID value. This key can serve as a lookup key in this map which you then use in your advice to resolve the actual value.