How to specify which version of a concrete implementation for an abstract class to autowire in Spring?

Having the following class structure:

public abstract class A {
    String someProperty = "property"

    public abstract void doSomething();
}

@Service
public class Aa extends A {

    @Override
    public abstract void doSomething() {
        System.out.println("I did");
    }
}

@Service
public class Ab extends A {

    @Override
    public abstract void doSomething() {
        System.out.println("I did something else");
    }
}

I need a way to tell Spring which A concrete class to Autowire in my Foo service, based on a property in a properties file.

@Service
public class Foo {

    @Autowire
    private A assignMeAConcreteClass;
}

And in my properties file I have this:

should-Aa-be-used: {true, false}