util:map key-type="java.lang.Class"

[mcbain]

Hi experts,
Is there a working example-xml-snippet wich shows correct usage of a Map<java.util.Class,xxx> bean-definition?

<util:map id="myMap" key-type="java.lang.Class" value-type="java.lang.String">
	<entry key="java.lang.String" value="Hallo"></entry>
</util:map>

should be mapped to

@Autowired
@Qualifier("myMap")
Map<java.util.Class,java.lang.String>

I always get the Exception:

 org.springframework.beans.FatalBeanException: Key type [class java.lang.Class] of map [java.util.Map] must be assignable to [java.lang.String]
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:435)
	at org.springframework.beans.factory.annotation.InjectionMetadata.injectFields(InjectionMetadata.java:105)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessAfterInstantiation(AutowiredAnnotationBeanPostProcessor.java:240)
	... 27 more
Caused by: org.springframework.beans.FatalBeanException: Key type [class java.lang.Class] of map [java.util.Map] must be assignable to [java.lang.String]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:585)
	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:412)
	... 29 more

I checked the spring-source-code at DefaultListableBeanFactory.resolveDependency(Defau ltListableBeanFactory.java:585).

Class keyType = descriptor.getMapKeyType();
			if (keyType == null || !String.class.isAssignableFrom(keyType)) {

but it seams that mapping a key-type of java.util.Class will never work since

String.class.isAssignableFrom( Class.class )

evaluates to 'false'

[mcbain]

As a workaround the bean can be injected by 'name' instead.

@Resource(name="myMap")
Map<...> myMap;

[ziimen]

Also refer to this post: http://forum.springsource.org/showthread.php?t=36331