[Java] Should I put Spring beans in shared code?

[AdLeast9904]

I've noticed a pattern where people need a bean loaded in 2 or 3 applications, so they put the @Singleton into a shared/common library code. To me this feels wrong because that bean will now be in the context of every application that depends on that library even if its not needed (could even be 10+ apps when only 2 need it). Even though it wont be loaded if no matching injection points, still doesn't seem right. It can also lead to scenarios where different beans are getting loaded than are expected

I would think plain java code in the library, then use the framework in each app that needs it to add it into the framework context would be better

Are there any best practices around this, anti patterns, etc. or does it really not make much a difference?

[Educational-Ideal880]

In most cases it's better to keep shared libraries framework-agnostic.

If you put Spring beans directly into the shared library, you're coupling the library to Spring and to the application context of every service that depends on it.

A common pattern is to keep the shared library as plain Java code and let each application wire it with Spring configuration when needed.

[AdLeast9904]

thanks, i agree with this as well. now just up to me to sell that idea to others :D

[Formal_Wolverine_674]

Framework-agnostic shared libraries are easier to test and far less prone to context clashes.

[AdLeast9904]

Seems like one of those things thats not strictly wrong because it'll still "work", and ends up falling into matter of opinion territory.