Spring 4-Autowire通用接口

Question

Starting with Spring (v4.3.8), I encounter a problem when Spring try to load dependency injections.

I want to call the "manage" method of the ManagerImpl1.java or ManagerImpl2.java implementation based on the type of T (Debit1 or Debit2). Here are the details:

Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'com.xxx.xxx.datacollection.infoprod.Manager' available: expected single matching bean but found 2: ManagerImpl1,ManagerImpl2

Business.java :

@Component
public class Business<T extends Debit> {

    @Autowired
    private Manager<T> manager;

    public void treatment(Context<T> context, FindServiceReturnMessage response) {

        manager.manage(response, context);
    }

Manager.java :

public interface Manager<T extends Debit> {

    void manage(final FindServiceReturnMessage response, Context<T> context);
}

ManagerImpl1.java :

@Component
public class ManagerImpl1 implements Manager<Debit1> {

    @Override
    public void manage(final FindServiceReturnMessage response, Context<Debit1> context) {

    }
}

ManagerImpl2.java :

@Component
public class ManagerImpl2 implements Manager<Debit2> {

    @Override
    public void manage(final FindServiceReturnMessage response, Context<Debit2> context) {

    }
}

Also, "Debit1" and "Debit2" implement the interface "Debit".

I tried several things but without success...

Answer 1

You need to add a qualifier on your Bean like the following:

@Component
@Qualifier("managerImpl2")
public class ManagerImpl2 implements Manager<Debit2> {

    @Override
    public void manage(final FindServiceReturnMessage response, Context<Debit2> context) 
    {

    }
}

Then, when you wanna use it, use once more your @Qualifier annotation:

@Component
public class Business<T extends Debit> {

    @Autowired
    @Qualifier("managerImpl2")
    private Manager<T> manager;

    public void treatment(Context<T> context, FindServiceReturnMessage response) {

        manager.manage(response, context);
    }
}

Yet, as @dvorog said in the comments, as Generics are not present at compile, you will probably have to make a Business interface like this:

public interface Business<T extends Debit> {

    public void treatment(Context<T> context, FindServiceReturnMessage response);
}

and implements BusinessImpl to specify it each time you have a new kind of Debit :

@Component
public class ManagerImpl2Business<Debit2> {

    @Autowired
    @Qualifier("managerImpl2")
    private Manager<Debit2> manager;

    public void treatment(Context<Debit2> context, FindServiceReturnMessage response) {

        manager.manage(response, context);
    }
}

This will repeat a step over and will probably end with some unmaintainable code, or some if (T instanceof Debit1) somewhere to make your genericity work.