Configure Implementation Class of Abstract Factory with Spring

Question

For my application, I have a Scale interface and multiple classes implementing this interface, for example NormalizedScale, LogScale,

Answer 1

As for spring 5.x there's a simpler and cleaner way of doing this. I have decided to use @ConditionalOnProperty annotation but you may choose any @Conditional* of your preference.

Here's the thing, I've have simplified to extreme:

public interface MyService {}

@Service
@ConditionalOnProperty(prefix = "myService", name = "Impl", havingValue = "Some")
public class SomeService implements MyService {}

@Service
@ConditionalOnProperty(prefix = "myService", name = "Impl", havingValue = "Foo")
public class FooService implements MyService {}

@Service
public class SimpleService {

  @Autowired
  SimpleService(MyService service) {
    // service instance will depend on configuration
  }
}

I'm using springboot so I've decided to use application.properties in order to set values via environment variables like this:

myService.Impl=${MY_SERVICE_IMPL}

Then, I have a fully dynamic injection based on environment variables that may be passed to a docker container for instance.