Spring @profile如何与继承一起使用？

Question

Currently in a project, I have parent abstract classes called page object classes which are subclassed typically by 2 or 3 child classes, each being used based on a specific configuration (For example: platform as Android, IOS, Web).

@Component
public abstract class MePage {}


@Profile("android")
@Component
public class AndroidMePage extends MePage {}


@Profile("ios")
@Component
public class IOSMePage extends MePage {}

Whenever an instance of one of the subclasses is needed, it's retrieved using

@Autowired
MePage mePage;

Question
How does Spring work in such cases where subclasses are annotated with @profile and the parent class is an abstract class and also a component?

Does Spring automatically assign instance of one of the subclasses to the @Autowired abstract class variable based on the profile configured?

Answer 1

You should not have @Component on top of an abstract class, since abstract classes are not meant to be instantiated (not event by Spring).

On top of that, Spring will inject the right bean based on your profile.

@Autowired
private MePage mePage; // AndroidMePage if android profile is active

@Autowired
private MePage mePage; // IOSMePage if ios profile is active

If your parent class is not abstract, you have to deal with multiple bean definitions as usual.

I think you have at least three options here.

1) Declare one of the beans as @Primary

@Component
public class MePage {}

@Profile("android")
@Component
@Primary
public class AndroidMePage extends MePage {}

@Profile("ios")
@Component
@Primary
public class IOSMePage extends MePage {}

@Autowired
private MePage mePage; // AndroidMePage if android profile is active

@Autowired
private MePage mePage; // IOSMePage if ios profile is active

2) Autowire a List of beans

@Component
public class MePage {}

@Profile("android")
@Component
public class AndroidMePage extends MePage {}

@Profile("ios")
@Component
public class IOSMePage extends MePage {}

@Autowired
private List<MePage> pages; // MePage and one of AndroidMePage or IOSMePage , based on active profile

3) Add @Qualifier to your bean definitions and use that when autowiring

@Component
@Qualifier("default")
public class MePage {}

@Profile("android")
@Component
@Qualifier("android")
public class AndroidMePage extends MePage {}

@Profile("ios")
@Component
@Qualifier("ios")
public class IOSMePage extends MePage {}

@Autowired
@Qualifier("default")
private MePage mePage; // MePage is injected, regardless of active profile

@Autowired
@Qualifier("ios")
private MePage mePage; // IOSMePage if ios profile is active

@Autowired
@Qualifier("android")
private MePage mePage; // AndroidMePage if android profile is active