If I use Class.getAnnotations to discover all the annotations on a class,
and the class includes annotations that are unknown to the runtime (e.g.,
because the class was annotated with vendor-specific annotations for one
app server and is being deployed on another app server), I get an exception
and can't discover any of the annotations on the class.  According to the
JSR-175 spec lead, unknown annotations must be ignored by getAnnotations.
Posted Date : 2005-09-10 00:23:52.0

N/A

I've reproduced the reported symptoms with a simple test case.  The stack trace for my test is

Exception in thread "main" java.lang.TypeNotPresentException: Type b.Bar not present
        at sun.reflect.generics.factory.CoreReflectionFactory.makeNamedType(CoreReflectionFactory.java:98)
        at sun.reflect.generics.visitor.Reifier.visitClassTypeSignature(Reifier.java:107)
        at sun.reflect.generics.tree.ClassTypeSignature.accept(ClassTypeSignature.java:31)
        at sun.reflect.annotation.AnnotationParser.parseSig(AnnotationParser.java:351)
        at sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:175)
        at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:69)
        at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:52)
        at java.lang.Class.initAnnotationsIfNecessary(Class.java:3005)
        at java.lang.Class.getAnnotations(Class.java:2987)
        at Test.main(Test.java:10)
Caused by: java.lang.ClassNotFoundException: b.Bar
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:242)
        at sun.reflect.generics.factory.CoreReflectionFactory.makeNamedType(CoreReflectionFactory.java:95)

The proximal cause for this problem seems to be the method sun.reflect.annotation.AnnotationParser.parseAnnotation catching NoClassDefFoundError instead of TypeNotPresentException; the latter is thrown by the ParseSig.  At the bottom of the stack, sun.reflect.generics.factory.CoreReflectionFactory does a Class.forName on the name of the annotation in question, catches any ClassNotFoundException and throws a TypeNotPresentException instead.

Adding a catch block at least gets the simple test case to pass; with this change the core reflection and annotation regression tests still pass too.

More analysis will be needed to verify this fix is sufficient and correct.
Posted Date : 2005-09-10 05:11:58.0