AnnotationAwareOrderComparator getPriority does not work if bean is a proxy [SPR-13884]

[spring-projects-issues]

Martin Frey opened SPR-13884 and commented

Identified a bug in the AnnotationAwareOrderComparator during investigating a NonUniqueBeanException with beans using the @Order / @Priority annotation.

First finding = bug:
The method AnnotationAwareOrderComparator.getPriority calls directly getClass() on the given beanInstance. This leads to no priority at all as the Proxy class (JdkProxy) does not contain the annotation. The fix seems reasonably easy: Just use the AopUtils.getTargetClass(beanInstance) instead of getClass().

AnnotationAwareOrderComparator

    public Integer getPriority(Object obj) {
        if (obj instanceof Class) {
            return OrderUtils.getPriority((Class<?>) obj);
        } else if (obj != null) {
            return OrderUtils.getPriority(AopUtils.getTargetClass(obj));
        }
        return null;
    }

Second finding = just to clarify:
Not sure if both @Order and @Priority should be supported by this? Currently only @Priority or @Primary seems to be used to identify autowire candidates via the DefaultListableBeanFactory.determineAutowireCandidate. Is this the desired behavior or should also the @Order annotation be considered here? As far as i remember @Priority was first introduced to support @Order with the standard API, and later also used to identify Primary candidates?

---

Affects: 4.2.3

Issue Links:

• DefaultAdvisorAutoProxyCreator doesn't get the target class of existing proxy [SPR-13990] #18563 DefaultAdvisorAutoProxyCreator doesn't get the target class of existing proxy
• GenericConversionService.addConverter should be able to determine generic types from target class behind proxy [SPR-14822] #19388 GenericConversionService.addConverter should be able to determine generic types from target class behind proxy

Referenced from: commits 6e3fac8

[spring-projects-issues]

Juergen Hoeller commented

As of 4.3, AnnotationAwareOrderComparator checks for the new DecoratingProxy interface, introspecting the decorated class behind a proxy as well. Interface-based Spring AOP proxy automatically expose this now, even behind multiple nested proxies.

With respect to @Order versus @Priority: This is actually intended... An order is just that: a sort order, whereas a priority also implies primary characteristics for the first element in the list. So in Spring terms, the use of @Priority kind of combines @Order with an @Primary marker for the first element.

Juergen