java - JPA 继承 IdClass

Question

如何在多重继承实体组合键情况下使用IdClass？

    @IdClass(IdClassEntity1.class)
    class Entity1 {
    private long e1pk1;
    private long e1pk2;
    }
    @IdClass(IdClassEntity2.class)
    class Entity2 extends Entity1  {
    private long e2pk1;
    private long e2pk2;
    }
    class Entity3 extends Entity2 {
    private long e3pk1;
    private long e3pk2;
    }

IdClassEntity2 应该是什么:

class IdClassEntity2 {
        private long e1pk1;
        private long e1pk2;
        private long e2pk1;
        private long e2pk2;
}

或

class IdClassEntity2 {
        private IdClassEntity1 idClassEntity1;
        private long e2pk1;
        private long e2pk2;
}

Answer 1

您可以使用@MappedSuperClass或@Entity来声明@IdClass。 pk 通过继承传播。

例如，使用@MappedSuperClass，您可以执行以下操作:

@MappedSuperClass
@IdClass(IdClassEntity1.class)
public class Entity1 {
    @Id private long e1pk;    
    @Id private long e1pk;
    ...

 @Entity
 public class Entity2 extends Entity1 {
    ...

使用@Entity，遵循相同的范例