java - 在通用父类(super class)中 Autowiring 通用组件

Question

我在Spring 4.0(使用Spring Boot)环境中遇到以下情况:

映射界面:

public interface EntityModelMapper<ENTITY extends AbstractEntity, MODEL extends AbstractModel>{ }

映射实现:

@Component
public class ProductEntityModelMapper implements EntityModelMapper<Product, ProductModel>{ }

服务:

public interface CrudService<MODEL extends AbstractModel>{ }

我想做一个像这样的抽象父类(super class)服务:

public abstract AbstractCrudService<ENTITY extends AbstractEntity, MODEL extends AbstractModel> implements CrudService<MODEL>{

@Autowired
private EntityModelMapper<ENTITY, MODEL> mapper;

  public EntityModelMapper<ENTITY, MODEL> getMapper(){ 
      return mapper; 
  }
}

所以我可以有这样的实现:

@Service
public ProductCrudService extends AbstractCrudService<Product, ProductModel>{

  public void someMethod(Product product){
    ProductModel model = getMapper().map(product);
  }

}

但是 Spring 告诉我它找不到 EntityModelMapper 的合格 bean 来注入(inject)服务类。这种情况是否可能，我做错了什么，或者我是否突破了 Spring 依赖注入(inject)的极限？

堆栈跟踪:

org.springframework.beans.factory.BeanCreationException:
 Error creating bean with name 'productCrudService':
 Injection of autowired dependencies failed;
 nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field:
 private com.flycatcher.seagull.mapper.EntityModelMapper 
com.flycatcher.seagull.facade.service.crud.AbstractCrudService.mapper;
 nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
 No qualifying bean of type [com.flycatcher.seagull.mapper.EntityModelMapper] found for dependency:
 expected at least 1 bean which qualifies as autowire candidate for this dependency.
 Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Answer 1

据此: https://spring.io/blog/2013/12/03/spring-framework-4-0-and-java-generics 从 Spring 4.0 版本开始就可以了。

这对我来说也不起作用。 (同样的异常，我使用 4.2.3)。 因此尝试升级到最新版本 - 4.2.6。

如果还是不行的话 您可以使用 @Qualifier 注释并 Autowiring EntityModelMapper 作为子类中的接口(interface)，并将 getMapper 定义为抽象:

  @Component
  @Qualifier("productEntityModelQualifier")
  public class ProductEntityModelMapper implements EntityModelMapper<Product, ProductModel>{ }

然后在 ProductCrudService 中:

@Service
public ProductCrudService extends AbstractCrudService<Product, ProductModel>{

  @Autowired
  @Qualifier("productEntityModelQualifier")
  EntityModelMapper<Product, ProductModel> mapper;

  @Override
  protected EntityModelMapper<Product, ProductModel> getMapper(){return mapper;}

  public void someMethod(Product product){
    ProductModel model = getMapper().map(product);
  }

}