Spring FactoryBean and scopes working together

Question

I\'d like to use FactoryBeans and scopes together. Specifically, I\'d like the object created and returned by a FactoryBean to be placed into a specified (perhaps custom) scope.

Answer 1

You can't easily use a custom scope on a bean returned from a FactoryBean.

From Spring's Java documentation:

FactoryBeans can support singletons and prototypes

If you want the FactoryBean's returned bean to have the prototype scope, then you must implement the isSingleton() method like this:

public class TestFactoryBean implements FactoryBean<TestBean> {

  // the rest of the required methods are removed for simplicity reasons..

  public boolean isSingleton() {
        return false;
    }
}

To support a custom scope, you have to implement the logic yourself and it will not be very intuitive, since the FactoryBean only provides the isSingleton() method. I will rather recommend using another solution than FactoryBean for beans with custom scope.

Hope this helps!

Answer 2

I solved the same issue using custom holder bean.

Factory bean:

@Component
@Configurable()
public class EventBusFactory implements FactoryBean<EventBus> {
    @Override
    public EventBus getObject() throws Exception {
        return new SimpleEventBus();
    }

    @Override
    public Class<?> getObjectType() {
        return EventBus.class;
    }

    @Override
    public boolean isSingleton() {
        return false;
    }
}

Bean holder:

@Configurable
@Component
@Scope("session")
public class EventBusHolder {

    @Autowired
    private EventBus eventBus;

    public EventBus getEventBus() {
        return eventBus;
    }

    public void setEventBus(EventBus eventBus) {
        this.eventBus = eventBus;
    }
}

And then I use holder instead of the required entity.

@Component
@Configurable
@Scope("session")
public class UicPlaceController extends PlaceController {

    @Autowired
    public UicPlaceController(EventBusHolder eventBus) {
        super(eventBus.getEventBus());
    }
    ...
 }

The solution looks a little bit ugly, but still, it solves the issue.