How to pick a bean based on a condition?

Question

I have two implementations of an interface

@Component
public ClassA implements SomeInterface {
}

@Component
public classB implements SomeInterface {
}

And then a consumer that needs an implementation of the class depending on some condition. How do I pick a particular bean?

@Component
public class Consumer {
  @PickTheRightBean(if(condition) then pick SomeClassA else pick SomeClassB) \\ how do I do this?
  private final SomeInterface myBean;
}

I tried @Conditional annotation, but it still ends up picking the wrong bean.

have you checked this question? https://stackoverflow.com/questions/40105044/inject-spring-bean-dynamically — zawarudo, Dec 09 '21 at 18:12
`@Conditional` doesn't work for auto wiring, you can place it on `ClassA` and `ClassB` or define bean via `@Bean` using `@Conditional` — geobreze, Dec 09 '21 at 18:12
Must be by injection ? If not, @Autowired Context context; SomeInterface some = cond ? context.getBean(ClassA.class) : context.getBean(ClassB.class); — PeterMmm, Dec 09 '21 at 18:41
@PeterMmm Yea that's what I thought - Spring doesn't offer this out of the box. One has to implement the logic. Thanks! — ritratt, Dec 09 '21 at 19:14

score 1 · Answer 1 · answered Dec 09 '21 at 20:43

The only feasible way to achieve what you want IMO, is to get rid of the annotation @Component on Consumer class so that it becomes

public class Consumer {
  
  private final SomeInterface myBean;
}

and you register it using your custom logic in a configuration class

 @Configuration
 public class MyConfiguration{

 @Bean
 public Consumer consumer(ClassA classA, ClassB classB) {

   Consumer consumer = new Consumer();
   if (your condition here){
        consumer.setMyBean(classA);
   } else {
        consumer.setMyBean(classB);
   }
   return consumer;
 }

}

How to pick a bean based on a condition?

1 Answers1