[Springframework-developer] Exception handling within the framework

[<jue...@we...>]

I've committed subtle changes to quite a few files, in an effort to =
generally refine our exception throwing and handling.

Most importantly, ApplicationContextException extends FatalBeanException =
now (analogous to BeanDefinitionStoreException). This finally clarifies =
how to propagate exceptions through bean lifecycle methods and bean post =
processors. For example, ApplicationContext.getBean throws =
BeansException but ApplicationContextAware's setApplicationContext =
method just threw ApplicationContextException. It now throws =
BeansException which covers both. Same for quite a few other points in =
the framework. My main goal was to make it clear that an =
ApplicationContextException should not get wrapped in a BeansException =
or vice versa, as the latter is just a specialization of the former.

Furthermore, BeanFactoryAware.setBeanFactory just throws BeansException =
instead of the former Exception, just like =
ApplicationContextAware.setApplicationContext already did before. The =
main rationale is consistency: Just =
InitializingBean.afterPropertiesSet/"init-method" and =
DisposableBean.destroy/"destroy-method" are allowed to throw any =
exception (the configurable reflection-based callbacks absolutely have =
to), every other callback encourages a certain kind of exception. =
Obviously, runtime exceptions like IllegalArgumentException and =
IllegalStateException can always be thrown.

The only additional try-catch block necessary was in =
AbstractPoolingInvokerInterceptor. Its setBeanFactory implementation now =
wraps exceptions from the underlying pooling tool in a =
BeanInitializationException. I consider it cleaner to have it the way it =
is now, for consistency within the framework. If there are strong =
objections, we can of course change setBeanFactory back to throw =
Exception. But I guess that BeanFactoryAware is hardly used in =
applications anyway; and if it is used, then mainly just for retrieving =
collaborating beans.

Juergen


DI J=FCrgen H=F6ller
Senior System Architect
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