Since the introduction of the AnnotationConfig(Web)ApplicationContext
types in Spring 3.0, it has been possible to specify a custom
bean name generation strategy via the #setBeanNameGenerator methods
available on each of these classes.
If specified, that BeanNameGenerator was delegated to the underlying
AnnotatedBeanDefinitionReader and ClassPathBeanDefinitionScanner. This
meant that any @Configuration classes registered or scanned directly
from the application context, e.g. via #register or #scan methods would
respect the custom name generation strategy as intended.
However, for @Configuration classes picked up via @Import or implicitly
registered due to being nested classes would not be aware of this
strategy, and would rather fall back to a hard-coded default
AnnotationBeanNameGenerator.
This change ensures consistent application of custom BeanNameGenerator
strategies in the following ways:
- Introduction of AnnotationConfigUtils#CONFIGURATION_BEAN_NAME_GENERATOR
singleton
If a custom BeanNameGenerator is specified via #setBeanNameGenerator
the AnnotationConfig* application contexts will, in addition to
delegating this object to the underlying reader and scanner, register
it as a singleton bean within the enclosing bean factory having the
constant name mentioned above.
ConfigurationClassPostProcessor now checks for the presence of this
singleton, falling back to a default AnnotationBeanNameGenerator if
not present. This singleton-based approach is necessary because it is
otherwise impossible to parameterize CCPP, given that it is
registered as a BeanDefinitionRegistryPostProcessor bean definition
in AnnotationConfigUtils#registerAnnotationConfigProcessors
- Introduction of ConfigurationClassPostProcessor#setBeanNameGenerator
As detailed in the Javadoc for this new method, this allows for
customizing the BeanNameGenerator via XML by dropping down to direct
registration of CCPP as a <bean> instead of using
<context:annotation-config> to enable @Configuration class
processing.
- Smarter defaulting for @ComponentScan#beanNameGenerator
Previously, @ComponentScan's #beanNameGenerator attribute had a
default value of AnnotationBeanNameGenerator. The value is now the
BeanNameGenerator interface itself, indicating that the scanner
dedicated to processing each @ComponentScan should fall back to an
inherited generator, i.e. the one originally specified against the
application context, or the original default provided by
ConfigurationClassPostProcessor. This means that name generation
strategies will be consistent with a single point of configuration,
but that individual @ComponentScan declarations may still customize
the strategy for the beans that are picked up by that particular
scanning.
Issue: SPR-9124
fc416bcb0b