java - Hibernate - 将关系及其管理委托(delegate)给子类以保持整洁

Question

现在我有一个 User 实体，其中包含其特定字段，如 id、name、password。用户也是 Item 实体的所有者，它们是多对一关系，反之亦然:

@Entity
@Table(name="users")
public class User {
    /* Id, name, password etc - strictly User specified */



    private List<Item> ownedItems;
    private List<Bike> ownedConsumables;


    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Item> getOwnedItems() {
        return ownedItems;
    }

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Consumable> getOwnedConsumables() {
        return ownedConsumables;
    }




    // a lot of methods to manage collections to keep one-to-many consistency 
    // which are not related to strictly to User entity
}

由于与此类组织(双向)相关的许多一致性问题，我想通过正确实现 addItem、removeItem 等方法来自行管理它们。这些与 User 实体没有直接关系，我认为我应该将此责任移交给另一个类(class)。我想到了:

@Table(name="users")
public class User {
    /* Id, name, password etc - strictly User specified */

    private Inventory inventory;
}




public class Inventory {
    private User owner; // if needed - I think it will

    private List<Item> ownedItems;
    private List<Bike> ownedConsumables;


    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Item> getOwnedItems() {
        return ownedItems;
    }

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "owner")
    @Fetch(FetchMode.SELECT)
    public List<Consumable> getOwnedConsumables() {
        return ownedConsumables;
    }

    // a lot of methods to manage collections to keep one-to-many consistency 
}

这可能与 Hibernate 有关吗？如何映射所有内容以正确填充这些集合？

另一个想法是创建一个类来检索 User 对象并管理集合，但这需要通过 getter 公开ownedItems 和ownedConsumables 字段。看起来更糟糕。

Answer 1

您可以通过使用 @Embeddable 注释该类并使用 @Embedded 注释字段 inventory 来实现此目的。