我有以下几种用于休眠实体层次结构的类。我试图有两个具体的子类Sub1Class
和Sub2Class
. 它们由field
中定义的鉴别器列 ( )分隔MappedSuperClass
。有一个抽象实体类EntitySuperClass
被其他实体引用。其他实体不应该关心它们是否实际引用Sub1Class
或Sub2Class
。
这实际上可能吗?目前我收到此错误(因为列定义在 Sub1Class 和 EntitySuperClass 中被继承了两次):
Repeated column in mapping for entity: my.package.Sub1Class column: field (should be mapped with insert="false" update="false")
如果我添加@MappedSuperClass
到EntitySuperClass
,那么我会从 hiberante 得到断言错误:它不喜欢一个类既是实体又是映射的超类。@Entity
如果我从中删除EntitySuperClass
,则该类不再是实体,并且无法从其他实体中引用:
MappedSuperClass
是外部包的一部分,所以如果可能的话,它不应该被改变。
我的课程:
@MappedSuperclass
public class MappedSuperClass {
private static final String ID_SEQ = "dummy_id_seq";
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = ID_SEQ)
@GenericGenerator(name=ID_SEQ, strategy="sequence")
@Column(name = "id", unique = true, nullable = false, insertable = true, updatable = false)
private Integer id;
@Column(name="field", nullable=false, length=8)
private String field;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getField() {
return field;
}
public void setField(String field) {
this.field = field;
}
}
@Entity
@Table(name = "ACTOR")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="field", discriminatorType=DiscriminatorType.STRING)
abstract public class EntitySuperClass extends MappedSuperClass {
@Column(name="description", nullable=false, length=8)
private String description;
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
@Entity
@DiscriminatorValue("sub1")
public class Sub1Class extends EntitySuperClass {
}
@Entity
@DiscriminatorValue("sub2")
public class Sub2Class extends EntitySuperClass {
}
@Entity
public class ReferencingEntity {
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE)
private Integer id;
@Column
private Integer value;
@ManyToOne
private EntitySuperClass entitySuperClass;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getValue() {
return value;
}
public void setValue(Integer value) {
this.value = value;
}
public EntitySuperClass getEntitySuperClass() {
return entitySuperClass;
}
public void setEntitySuperClass(EntitySuperClass entitySuperClass) {
this.entitySuperClass = entitySuperClass;
}
}