Usage of @Bean annotation

Question

Suppose I have the following Spring context configuration:

@Configuration
public class Configuration {

    @Bean
    public A a() {
        return new A(b());
    }

    public B b() {
        return new B();
    }
}

Should one annotate b() with @Bean if the only place where B instance needed is within a() for A instance construction?

Answer 1

If B is a plan Java class (no Spring annotations) then no, You can use current configuration. As this is a private member of A class.

But if you have methods that need to be managed by spring (inside B class), like @PostConstruct or @PreDestroy, than you should make a Bean out of B class:

@Bean
public A a(B b) {
    return new A(b);
}
@Bean
public B b() {
    return new B();
}

Such cases are:

• resource to be closed on shutdown/close
• executors to be closed on shutdown
• jdbc connections
• etc