Provide functionality similar to Spring Boot's BeanTypeRegistry

[philwebb]

Spring Boot currently has an internal class called BeanTypeRegistry that is used by @ConditionalOnBean and @ConditionalOnMissingBean. We've have a recent issue where we need something similar, but rather than make it public in Spring Boot it might be better if Spring Framework could offer methods that we could use.

What we specifically need is a way to predict the bean type in a way that's very fast to call during condition evaluation and doesn't cause any early initialization of any beans (including FactoryBeans).

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After some analysis, I'm going to split this issue up into a number of smaller parts:

• Add missing ResolvableType variants of getBeanNamesForType (Add missing ResolvableType variants of getBeanNamesForType #23335)
• Retain merged bean definition caches during post processing (Retain merged bean definition caches during post processing #23336)
• Cache isFactoryBean detection (Cache isFactoryBean detection #23337)
• Consider generics when predicting FactoryBean types (Consider generics when predicting FactoryBean types #23338)
• Add attribute support for FactoryBean bean definitions (Add attribute support for FactoryBean bean definitions #23339)
• Use static final constants for common zero length arrays (Use static final constants for common zero length arrays #23340)

[tkvangorder]

@philwebb Any movement on this issue? I could take a stab at PR for this, but I would need some guidance on which package to move the code and/or what to rename the BeanTypeRegistry such that it conforms to how things are organized in the core Spring framework.

[philwebb]

Thanks for the offer @tkvangorder but I'm already in the middle of trying various changes. We won't be able to migrate BeanTypeRegistry as it is, instead we need to look at changing some of the core BeanFactory implementations. Unfortunately that's quite a complex part of the codebase so it's taking some time.

[tkvangorder]

yep, not for the faint of heart. 8) Make sense, thank you!