使用Spring在工厂中使用具有相同接口的注入bean的最佳方法是什么？

Question

I created one factory to decide what best implementation should be returned, based in some conditional check.

// Factory
@Component
public class StoreServiceFactory {

    @Autowired
    private List<StoreService> storeServices;

    public StoreService getService(){

        if(isActiveSale){
            return storeServices.get("PublicStoreService")
        }

        return storeServices.get("PrivateStoreService")
    }
}

//Service Implementations
@Service
@Qualifier("PublicStoreService")
public class PublicStoreService implements StoreService {

    public getStoreBalanceScore(){
        Do Stuff....
    }
}

@Service
@Qualifier("PrivateStoreService")
public class PrivateStoreService implements StoreService {

    public getStoreBalanceScore(){
        Do Stuff....
    }
}


    // Controller
    @Autowired
    StoreServiceFactory storeServiceFactory;

    @Override
    public StoreData getStoreBalance(String storeId) {
        StoreService storeService = storeServiceFactory.getService();
        return simulationService.simulate(sellerId, simulation);
    }

Is this approach good? If yes, how can i get my service from an elegant way? I would like to use only annotations, without configurations.

Answer 1

You should use a map instead of a List and pass a string parameter to the getService method.

public class StoreServiceFactory {

    @Autowired
    private Map<String,StoreService> storeServices = new HashMap<>();

    public StoreService getService(String serviceName){

        if(some condition...){
            // want to return specific implementation on storeServices map, but using @Qualifier os something else
            storeServices.get(serviceName)
        }
    }
}

You can prepopulate the map with supported implementations. You can then get an appropriate service instance as follows :

    // Controller
    @Autowired
    StoreServiceFactory storeServiceFactory;

    @Override
    public StoreData getStoreBalance(String storeId) {
        StoreService storeService = storeServiceFactory.getService("private");//not sure but you could pass storeId as a parameter to getService
        return simulationService.simulate(sellerId, simulation);
    }

If you don't like using Strings, you can define an enum for the supported implementations and use that as the key for your map.

Answer 2

You don't need to create a list or map on your code. You can retrieve it directly from Spring context using GenericBeanFactoryAccessor . This has various method to retrieve a specific bean like based on name, annotation etc. You can take a look at javadoc here. This avoids unnecessary complexity.

http://docs.spring.io/spring-framework/docs/2.5.6/api/org/springframework/beans/factory/generic/GenericBeanFactoryAccessor.html