在Spring中以编程方式解析AliasFor批注值

Question

I have an annotation

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface A {
    Class<?> value();
}

and another annotation that uses @AliasFor

@A (Void.class)
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface B {

    @AliasFor(annotation = A.class)
    Class<?> value();
}

which is used on class

@B(D.class)
public class C implements D {
}

If I have an instance of C , how can I programatically resolve A.value() to Class<D> ? I'm trying to synthesise the annotation with AnnotationUtils but when I retrieve the value I'm constantly getting Class<Void> .

Answer 1

After some digging around, the answer is that I've used the wrong class. Instead of AnnotationUtils it can be done with AnnotatedElementUtils :

@Test
public void shouldFindAliasedValue() {

    Class<?> actual = AnnotatedElementUtils.findMergedAnnotation(C.class, A.class).value();

    then(actual).isEqualTo(D.class);
}