java - Hibernate继承，多态保存

Question

我有一个类Person有两个子类 Student和 Employee

@Entity(name="person")
@Inheritance(strategy = InheritanceType.JOINED)
public class Person implements Serializable {
    @Id
    @GeneratedValue
    private Integer id;
}

@Entity(name="student")
@PrimaryKeyJoinColumn(name="id")
public class Student extends Pessoa implements Serializable {
}

@Entity(name="employee")
@PrimaryKeyJoinColumn(name="id")
public class Employee extends Person implements Serializable {
}

学生也可以是雇员，但是当我尝试保存与雇员具有相同 id 的学生时，hibernate 会抛出重复的主键异常

org.hibernate.exception.ConstraintViolationException: Duplicate entry '142.855.267-71' for key 'PRIMARY'

hibernate 试图在数据库中插入一个新人，我不希望那样。

有没有办法让hibernate识别数据库中已经存在一个人并只保存对这个人的引用？

顺便说一句:当我手动插入一个学生和一个员工时，一切都像魅力一样。

Answer 1

您需要指定表和列映射。以下是每个子类映射的表。

@Entity(name="person")
@Table(name = "PERSON")
@Inheritance(strategy = InheritanceType.JOINED)
public class Person implements Serializable {
    @Id
    @GeneratedValue
    @Column(name = "ID")
    private Integer id;
}

@Entity(name="student")
@Table(name="STUDENT")
@PrimaryKeyJoinColumn(name="id")
public class Student extends Pessoa implements Serializable {
}

@Entity(name="employee")
@Table(name="EMPLOYEE")
@PrimaryKeyJoinColumn(name="id")
public class Employee extends Person implements Serializable {
}