Document method visibility rules for @Bean methods [SPR-12345]

[spring-projects-issues]

Bob Tiernay opened SPR-12345 and commented

There used to be documentation in the JavaConfig project that discussed the effect of method visibility on bean scope:

http://docs.spring.io/spring-javaconfig/docs/1.0-m2/reference/html/bean-visibility.html

This documentation does not appear to exist in:

http://docs.spring.io/spring-framework/docs/current/spring-framework-reference/html/beans.html#beans-factorybeans-annotations

However, there is an example in that section regarding a privateInstance but the semantics are still undefined. I am still unclear what effect marking an @Bean method private has. I was hoping it would make it private to the @Configuration as that could be very useful in certain circumstances.

Nevertheless, it would be extremely useful to document these semantics.

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Affects: 4.1.1

Referenced from: commits f58e1db

[spring-projects-issues]

Juergen Hoeller commented

I've added a note on @Bean method visibility to the reference documentation now.

In the end, the declared Java language visibility has no immediate impact on the resulting bean definition. A private @Bean method may still get obtained and autowired in other places.

Actually, the most important part is that @Bean methods must not be declared as private or final in regular @Configuration classes since those methods need to be overridable in order to redirect direct method calls back to the container. With @Bean methods on non-@Configuration classes and static @Bean methods anywhere, no such limitations apply.

Juergen