ProxyMode: Prototype Dependency of a Singleton Bean

 

Default scope is singleton, what to do prototype?

@Component
@Scope("prototype")
public class Dependency {

What if a bean use this component as a dependency and we want this dependency prototype for every single instance of the bean?

Bean:

@Component
public class Service_Impl implements Service {

    @Autowired
    public Dependency dependency;

    @Override
    public void print() {
        System.out.println(dependency);
    }
}

Application contex

@SpringBootApplication
public class DemoApplication implements CommandLineRunner {

   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }

   @Autowired
   public Service service1;
   @Autowired
   public Service service2;

   @Override
   public void run(String... args) throws Exception {
      service1.print();
      service2.print();
   }
}

Even if the dependency scope set as prototype, output will be:

com.example.demo.Dependency@43e9e0b1

com.example.demo.Dependency@43e9e0b1

which means same hash code and dependency is still singleton.

If we define proxyMode in @Scope annotation, it will work:

@Component
@Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE, 
        proxyMode = ScopedProxyMode.TARGET_CLASS)
public class Dependency {

 

and output will be:

com.example.demo.Dependency@3eab8a9d

com.example.demo.Dependency@544b6c7c