JPA：是否有某种方法可以实现可嵌入的继承
以下是示例代码：
class Resource {
Long id;
@Embedded
GPU gpu;
CPU cpu;
}
abstract class GPU {
String name;
GpuType type;
}
class PhysicalGPU extends GPU {
}
class VirtualGPU extends GPU {
private int partition;
}
我有一个实体Resource，它有一个字段GPU，它是一个超类。它可以是VirtualGPU或PhysicalGPU。但 JPA 或 Hibernate 似乎不支持 @Embedded 字段的类继承。创建没有继承的单一 GPU 类型或创建PhysicalGPUResource 和VirtualGPUResource 来实现单个字段的继承是很丑陋的。
我认为作为 Resource 的描述符，使 GPU 成为单独表中的关联（并在 ManyToOne 关系中给出>Resource）也不是一个好的实践，但这将使继承可用。
我做了一些搜索，我想现在的答案是否定的。但我仍然认为这对于 Hibernate ORM 来说是一个相当大的要求，它可以在像 MyBatis 这样的框架中实现，很奇怪的是 Hibernate 不支持这种行为。那么也许还有其他方法可以做到这一点？
Here is the example code:
class Resource {
Long id;
@Embedded
GPU gpu;
CPU cpu;
}
abstract class GPU {
String name;
GpuType type;
}
class PhysicalGPU extends GPU {
}
class VirtualGPU extends GPU {
private int partition;
}
I have an Entity Resource and it has a field GPU which is a superclass. It can be a VirtualGPU or PhysicalGPU. But JPA or Hibernate seems not support class inheritance for @Embedded fields. And it is ugly to create a single GPU type with no inheritance or create PhysicalGPUResource and VirtualGPUResource to implement the inheritance for a single field.
And I think as a descriptor of a Resource, make the GPU be an association in a seperate table (and give a ManyToOne relation in Resource) is also not a good practice but this will make the Inheritance available.
I did some search and I think right now the answer is no. But I still think this is a quite big requirement for the Hibernate ORM and it can be implemented in some framework like MyBatis, it is quite weird that Hibernate do not support this behavior. So maybe there is some other way to make this done?
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我认为当前最好的方法是使用USERTYPE。遵循文章 hibernate中的自定义类型和@Type注释可以很有帮助。
但是我仍然不知道
CompositeUsertype的优势是什么。I think current the best way is using UserType. Follow the article Custom Types in Hibernate and the @Type Annotation can be very helpful.
But I still don't know what is the advantage of the
CompositeUserType.