Using @Qualifier and @Bean together in Java Config Spring

Question

I have follow code

   interface Drivable{

}

@Component
class Bmw implements Drivable {

}

@Component
class Mercedes implements Drivable {

}

class Driver         


        

Answer 1

You could define qualifiers for each specific implementations of interface Drivable. Once you did, now you could autowire them into CarConfig class and you have to be create Beans for each Drivers(Mercedz & Benz) along with qualifier names.

Find below Implementation:

 @Target({ElementType.FIELD, ElementType.PARAMETER})
 @Retention(RetentionPolicy.RUNTIME)
 @Qualifier
 public @interface Bmw {
 }

 @Target({ElementType.FIELD, ElementType.PARAMETER})
 @Retention(RetentionPolicy.RUNTIME)
 @Qualifier
 public @interface Mercedes {
 }

Now your Interface Implementations of Driver should be annotated with Qualifiers as below

@Compoenent
@Bmw
public interface Bmw implements Drivable{
}

@Component
@Mercedes
public interface Mercedes implements Drivable{
}

Your CarConfig class should be as below:

@Configuration
public class CarConfig{

@autowire
@Bmw
private Drivable bmwDriver;

@autowire
@Mercedes
private Drivable mercedesDriver;


@Bean
public Bean getBmwDriver(){
  return new Bmw(bmwDriver);
  }

 @Bean
public Bean getMercedesDriver(){
   return new Mercedes(mercedesDriver);
  }

 }

NOTE: if you are creating bean with @Bean, it will be injected byType if there is duplicates then it will injected byName. we no need to mention @Bean(name="bmwDriver") . so you can directly use qualifier("bmwDriver") wherever you need in classes.