How to choose what implementation get's injected in to an autowired constructor

Question

Say I have an interface

interface IPerson {...}

I have two implementations of this interface

@Component
class Programmer implements IPerson {...}

@Component
class LionTamer implements IPerson {...}

Say I have a class that uses Autowire injection

@Component
class SomethingThatDoesStuff { 

    @Autowired
    public SomethingThatDoesStuff (IPerson someone) {
        ...
    }

}

How does Spring know what implementation to inject? Is there a way to tell spring what implementation to inject? Can this be done via the annotation or do I have to define some sort of factory? If so how?

Answer 1

As @passion mentioned, you should use bean naming (standard Spring IoC feature):

@Component("programmer")
class Programmer implements IPerson {...}

@Component("lionTamer")
class LionTamer implements IPerson {...}

@Component
class SomethingThatDoesStuff { 

    @Autowired
    public SomethingThatDoesStuff (@Qualifier("programmer") IPerson someone) {
        ...
    }

}