Class annotations and weld proxies

[ron_sigal]

Hi,

I'm finding that calling getAnnotations() on the class of a weld proxy, e.g., org.jboss.resteasy.test.providers.priority.resource.ProviderPriorityFooParamConverterProviderAAA$Proxy$_$$_WeldClientProxy, doesn't return the annotations on the original class, in the case org.jboss.resteasy.test.providers.priority.resource.ProviderPriorityFooParamConverterProviderAAA. Is there a way to preserve the annotations?

-Ron

[ron_sigal]

By the way, this question arises on [RESTEASY-1739] Order ParamConverterProviders and ExceptionMappers by @Priority - JBoss Issue Tracker

[mkouba]

Hi Ron,

this is a known issue. See also WELD-1539 and WELD-2423. There are some technical problems which prevent from implementing this correctly. Also I'm not 100% sure but I believe annotations are preserved on methods of a proxy.

[ron_sigal]

Ah, thanks, Martin.

One thing I've tried is just editing "org.jboss.resteasy.test.providers.priority.resource.ProviderPriorityFooParamConverterProviderAAA$Proxy$_$$_WeldClientProxy" to "org.jboss.resteasy.test.providers.priority.resource.ProviderPriorityFooParamConverterProviderAAA" and loading:

   String o1Class = o1.getClass().getName();

   o1Class = o1Class.substring(0, o1Class.indexOf("$"));

   Class<?> o1Clazz = Thread.currentThread().getContextClassLoader().loadClass(o1Class);

   Annotation[] o1as = o1Clazz.getAnnotations();

It works, but it's not very nice. After several years, though, I'm guessing that the naming convention of adding "$Proxy$_$$_WeldClientProxy" is likely to be around for a while. What do you think?

-Ron

[mkouba]

Well, since Weld 2.3 all "proxy" constructs (i.e. client proxies and subclasses) are marked with SYNTHETIC modifier. So you use this check to be sure. And since Weld 3.0.1 special marker interfaces are part of the API (see also api/weld/src/main/java/org/jboss/weld/proxy at 3.0.SP1 · weld/api · GitHub ). Also it's not necessary to parse the name and load the class again. Instead, inspect the subclass via reflection (Weld is using subclassing for both client proxies and interception).

[ron_sigal]

Hey Martin,

The fact that the proxy class is a subclass of the original class - that's fantastically useful. I never knew that. I feel much better about the solution. It's so much simpler and prettier - just

   Class<?> clazz = o.getClass();

   clazz = clazz.isSynthetic() ? clazz.getSuperClass() : clazz;

   Priority priority = clazz.getAnnotation(Priority.class);

Fantastic!!

Thanks,

Ron