Spring @Import values are plain classes without @Configuration

Question

Refer to the code, the imported "SomeController.class" do not annotated with @Configuration,@Controller or @Component, but it is indeed worked.

Is it reasonable, any potential problems here?

@Import(SomeController.class)
@Configuration
public class MyConfiguration{
}


public class SomeController{
    @Inject SomeService someService;
    ....
}

Answer 1

I'm the asker. Here is my conclusion with my testing:

Using @Import(Any.class) and Any.class is not under Spring component scan scope:
1. If Any.class do not annotated with any annotations, Spring will create the bean named by full class: com.xxx.Any

2. If Any.class annotated with @Component and so on, Spring will create the bean named by full class: com.xxx.Any

3. If Any.class annotated with @Component("anyBean") and so on, Spring will create the bean named : anyBean

BTW, If Any.class is under Spring component scan scope, we do not need @Import it, and Spring will create the bean named : any

Answer 2

Scanning/importing etc is only required to find beans which otherwise will not be found. If Spring sees bean is required then it will load and initialize it anyway.

For example,

@Service
public class MyService {
  @Autowire MyComponent myComponent;
}

Even if MyComponent is not marked by any annotation and not imported by any @Import then it will be instantiated by Spring just because it is required for MyService .

You can think of @Import etc as entry points for Spring, ie where to start to look for beans and then it will pull whole hierarchy.