我想为两个域对象创建一个通用存储库类: 产品和类别,并能够列出index.html 中的所有元素。
这是我的代码:
@Controller
public class IndexController {
private final ProdCatService<Category> categoryProdCatService;
public IndexController(ProdCatService<Category> categoryProdCatService) {
this.categoryProdCatService = categoryProdCatService;
}
@RequestMapping({"","/","index"})
public String getIndexPage(Model model)
{
model.addAttribute("cat", categoryProdCatService.getAll());
return "index";
}
}
存储库:
public interface ProdCatRepository<T> extends CrudRepository<T, Long> { }
服务:
public interface ProdCatService<T> {
Set<T> getAll();
T findById(Long id);
}
@Service
public class ProdCatServiceImpl<T> implements ProdCatService {
private final ProdCatRepository<T> prodCatRepository;
public ProdCatServiceImpl(ProdCatRepository<T> prodCatRepository) {
this.prodCatRepository = prodCatRepository;
}
@Override
public Set<T> getAll() {
Set<T> productsSet = new HashSet<>();
prodCatRepository.findAll().iterator().forEachRemaining(productsSet::add);
return productsSet;
}
@Override
public T findById(Long id) {
return prodCatRepository.findById(id).get();
}
}
所以问题是我遇到了一系列错误,例如:
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'indexController' defined in file [C:\Users\Michał\Documents\webstore-v-1\target\classes\info\mike\webstorev1\controllers\IndexController.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'prodCatServiceImpl' defined in file [C:\Users\Michał\Documents\webstore-v-1\target\classes\info\mike\webstorev1\service\ProdCatServiceImpl.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'prodCatRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object
和
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'prodCatRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class java.lang.Object
我正在寻求帮助。我查看了 S/O,但找不到答案。
编辑类别域类。
@Entity
public class Category {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String categoryName;
@ManyToMany(mappedBy = "categories")
private Set<Product> products;
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Category other = (Category) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
最佳答案
I want to create a generic repository class for two domain objects: Product and Category and be able to list all elements in index.html.
你的要求毫无意义。
为了实现它,您应该在 Product 和 Category 之间定义一个基类,并在通用存储库中指定这个基类。
类别是与产品不同的概念。
因此,如果扭曲层次结构,您将无法定义这个基类。
即使您定义了它,它也不会反射(reflect)类别和产品中所需的字段。
那么在这些情况下,您希望如何在客户端正确列出它们?
那么,为什么要重新发明轮子呢?
实际上,您使用 Spring Data 来减少样板代码:
public interface ProdCatRepository<T> extends CrudRepository<T, Long> { }
这已经足够清楚并且易于声明。
不要试图太聪明地关联不应该关联的事物,并为每个事物定义一个不同的存储库:
public interface ProductRepository extends CrudRepository<Product, Long> { }
public interface CategoryRepository extends CrudRepository<Category, Long> { }
关于Spring UnsatisfiedDependencyException 且不是托管类型 : class java. lang.Object,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48064471/