Spring Boot Autowired对CrudRepository的支持

Question

The Spring Boot CrudRepository interface seems to help me well once JPA entities are all set up. I have a situation where I'd like to create these CrudRepository instances as needed and not always based on @ Autowired annotation. For example, in my use case, I have a GUI menu that will contain a list of domain (or reference) table names. Depending on what the user selects, the program will then instantiate one of these CrudRepository implementations.

If I use @Autowired , then don't I have to end up with all possible known implementation in my code?

One hypothetical use case:

public interface PublisherRepository extends CrudRepository<Publisher, Long> {
}

public interface AuthorRepository extends CrudRepository<Author, Long> {
}

(I just realized I still have to create these entities after all.)

In the GUI menu, there will be "Publisher", "Author", etc., and I like to create the GUI maintenance components based on the above repository interfaces. Would it be a good practice to put @Autowired as following or just create them dynamically?

@Autowired
PublisherRepository publisherRepo;

@Autowired
AuthorRepository authorRepo;

If there were a way to create these repo instances, would you please teach me how that is done in Spring Boot? Thanks so much for the expertise sharing in advance!

Sincerely,

Student_t

Answer 1

Normally, beans are created eagerly, so @Autowiring not used beans is not a problem. They will use memory and consume some startup time anyway.

If you really do not want to autowire, you may @Autowire org.springframework.beans.factory.BeanFactory and use getBean to get desired repository. But this is terrible idea. This ties your @Service to Spring, and (in case your repository is not found) you will get late (during access) runtime exception, rather than startup-exception.