How to integrate a factory method which accepts Class<T> and produces T into Spring

Question

I have a factory object which implements something like the following:

public interface MyFactory {

    <T> T getInstance(Class<T> clazz);
}

It can be used like this:

MyService s = factory.getInstance(MyService.class);

It can produce many kinds of instances based on clazz. If it gets a clazz which is not supported by the factory object, it returns null.

Now I'm writing a Spring application (Spring Boot 2.0.1) and want to use its injection mechanism with the factory object. For example, I want to do something like this:

@Controller
public class MyController {

    @Autowired
    private MyService s;
}

Is there any way to integrate the MyFactory object into Spring like this? I know I can create bindings for each class manually but I'm looking for an easier way.

Answer 1

I added the following method which returns a set of classes the factory object supports:

Set<Class<?>> getSupportedClasses();

Then I put the following class into my Spring app and it seems to be working fine:

@Component
@Scope(value = ConfigurableBeanFactory.SCOPE_SINGLETON)
public class SomeBean {

  private static final Logger log = LoggerFactory.getLogger(SomeBean.class);

  private final MyFactory factory;
  private final GenericApplicationContext context;

  @Autowired
  public SomeBean(GenericApplicationContext context, MyFactory factory) {
    this.context = context;
    this.factory = factory;
  }

  @PostConstruct
  public void init() {
    factory.getSupportedClasses().forEach(this::register);
  }

  private <T> void register(Class<T> clazz) {
    log.info("Registering {} as a bean into ApplicationContext", clazz);
    context.registerBean(clazz,
        () -> factory.getInstance(clazz),
        (beanDefinition -> beanDefinition.setScope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)));
  }
}