How does Spring @Configuration cache references to beans

Question

How does Spring prevent a second call to bar() when using Java based configurations?

I\'m wondering compile time annotation processing or by proxying the method?

Answer 1

Spring does not "prevent" a call to bar(). Instead, at startup, spring generates a list of @Bean marked methods then calls each method one time. If you want, you can call bar() a hundred times. Spring, however; will only call it one time.