java - @SequenceGenerator 在用@MappedSuperclass 注释的类上

Question

我的实体结构如下:

@MappedSuperclass
public abstract class BaseEntity {
  @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seqGenerator")
  private Long id;
}

@MappedSuperclass
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@SequenceGenerator(name = "seqGenerator", sequenceName = "DICTIONARY_SEQ")
public abstract class Intermed extends BaseEntity {}

@Entity
public class MyEntity1 extends Intermed {}

@Entity
public class MyEntity2 extends Intermed {}

我得到以下异常:

    Caused by: org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'sessionFactory' defined in class path resource [context/applicationContext.xml]: 
Invocation of init method failed; nested exception is org.hibernate.AnnotationException: Unknown Id.generator: seqGenerator

当我在 Intermed 类上将 @MappedSuperclass 更改为 @Entity 时，一切正常。 使用@MappedSuperclass 和@SequenceGenerator 有什么问题吗？或者我错过了什么？

Answer 1

我在尝试实现应用程序范围的 ID 生成器时遇到了这个问题中描述的相同问题。

解决方案其实在第一个答案中:将序列生成器放在主键字段上。

像这样:

@MappedSuperclass
public abstract class BaseEntity {
  @Id
  @SequenceGenerator(name = "seqGenerator", sequenceName = "DICTIONARY_SEQ")
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seqGenerator")
  private Long id;
}

@MappedSuperclass
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public abstract class Intermed extends BaseEntity {}

@Entity
public class MyEntity1 extends Intermed {}

@Entity
public class MyEntity2 extends Intermed {}

虽然以这种方式做事似乎非常愚蠢(至少对我而言)，但它确实有效。