java - 如何创建注入(inject)特定@Repository的通用@Service？

Question

我们的软件具有适用于所有功能的特定行为，大多数情况下更改的是操作中使用的实体，为此我们需要 @Repository 层的特定实现。

因此，我们开发了一个“简单”架构 @RestController -> @Service -> @Repository 以及一些泛型，以供使用所有功能。像这样:

@RestController
@RequestMapping("test")
// This is specific implementation
public class DiariasApi implements DefaultApiInterface<DiariasDTO, DiariasDTOFilter, Integer> {

    @Autowired
    private DefaultService<DiariasDTO, DiariasDTOFilter, Integer> defaultService;

    @Override
    @GetMapping("/page")
    public Page<DiariasDTO> pageSearch(final DiariasDTOFilter filter) {
        return this.defaultService.pageSearch(filter);
    }

    @Override
    @GetMapping("/detail")
    public DiariasDTO detail(@PathVariable("key") final Integer key) {
        return this.defaultService.detail(key);
    }

}

@Service
// This is generic implementation
public class DefaultService<D extends Serializable, F extends Serializable, C> {

    @Autowired
    // The Problem is here.
   // Here I want the call to be the specific @Repository.
    private DefaultRepositoryInterface<D, F, C> defaultRepository;

    @Transactional(readOnly = true)
    public Page<D> pageSearch(final F filter) {
        return this.defaultRepository.pageSearch(filter);
    }

    @Transactional(readOnly = true)
    public D detail(final C key) {
        return this.defaultRepository.detail(key);
    }

}

@Repository
// This is specific implementation
public class DiariasRepository implements DefaultRepositoryInterface<DiariasDTO, DiariasDTOFilter, Integer> {

    @Override
    public Page<DiariasDTO> pageSearch(final DiariasFiltro filtro) {
        //some specific code;
    }

    @Override
    public Optional<DiariasDTO> detail(final Integer key) {
        //some specific code;
    }

我们只想为每个功能实现@RestController和@Repository，并让@Service层只是一个通用层bean 知道如何调用特定的@Repository。但是，当我们这样做并且有多个实现时，我们会收到以下错误消息，它告诉我们 @Autowired 的问题:

Description:
Field defaultRepository in package.DefaultService required a single bean, but 2 were found:
    - conveniosRepository: defined in file ...
    - diariasRepository: defined in file ...

我们希望@Service层是唯一的，我们可以做到吗？

Answer 1

您需要使用@Qualifier来绑定(bind)特定的bean实例

@Service
// This is generic implementation
 public class DefaultService<D extends Serializable, F extends Serializable, C> {

@Autowired
// The Problem is here.
// Here I want the call to be the specific @Repository.
@Qualifier("YourBeanId")
private DefaultRepositoryInterface<D, F, C> defaultRepository;

编辑

所以你可以使用我过去在本地v/s测试环境中使用的另一种方法

类似工厂的类，将在运行时返回 bean 的特定实例

创建工厂类

@Component
public class RepositoryFactoryImpl implements RepositoryFactory{

@Autowired
private DefaultRepositoryInterface conveniosRepository;

@Autowired
private DefaultRepositoryInterface diariasRepository;

@Override
public DefaultRepositoryInterface getInstance() {
    if (some condition) {
        return conveniosRepository;
    }

    if (some condition) {
        return diariasRepository;
    }
    return null;
   }
}

然后在您的DefaultService

@Service
// This is generic implementation
public class DefaultService<D extends Serializable, F extends Serializable, C> {

    @Autowired
    private RepositoryFactory factory;

    @Transactional(readOnly = true)
    public Page<D> pageSearch(final F filter) {
        return this.factory.getInstance().pageSearch(filter);
    }

    @Transactional(readOnly = true)
    public D detail(final C key) {
        return this.factory.getInstance().detail(key);
    }
 }