渴望多次取货

Question

我在使用JPA批注时遇到问题。 我创建了3个表：  -类别  -类别_产品  -产品  

我为类别，产品和数据透视表创建了3个不同的实体：

@Entity
@Table(name="categories")
@NamedQuery(name="Category.findAll", query="SELECT c FROM Category c")
public class Category implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id")
    private Long id;

    @Column(name="name")
    private String name;

    @ManyToOne(cascade={CascadeType.ALL})
    @JoinColumn(name="category_id")
    @JsonBackReference
    private Category parentCategory;

    @OneToMany(mappedBy="parentCategory", fetch = FetchType.EAGER)
    @JsonManagedReference
    private List<Category> childCategory;

    public Category() {
    }

    // Getters and setters
}

我的产品实体：

@Entity
@Table(name="products")
@NamedQuery(name="Product.findAll", query="SELECT p FROM Product p")
public class Product implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;
    private String name;
    @Lob
    private String description;
    private int instock;
    private BigDecimal unitprice;
    private int createdat;
    private int updatedat;

    @OneToMany(fetch = FetchType.EAGER)
    @JoinColumn(name = "product_id")
    private List<Image> images;

    public Product() {}

    // getters and setters
}

还有我的数据透视表：

@Entity
@Table(name="categories_products")
@NamedQuery(name="CategoriesProduct.findAll", query="SELECT c FROM CategoriesProduct c")
public class CategoriesProduct implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id")
    private Long id;

    @Column(name="category_id")
    private int categoryId;

    @Column(name="product_id")
    private int productId;

    // Getters and setters
}

实际上，我需要查看某个类别的产品和该产品的类别，我被困住了，因为似乎我们无法两次获得渴望的产品。对于类别，我已经有一个用于获取子类别的oneToMany，对于产品而言，已经具有用于获取产品照片的oneToMany