java - x.person 上的@OneToOne 或@ManyToOne 引用未知实体 : y. Person - 继承问题

Question

我的 Hibernate 架构有问题:

我有一个 MappedSuperClass Person、一个 Employee 和一个 Customer。

--> Person.class
@MappedSuperclass
@Audited
public class Person extends PersistentObject {

    @Column(name="TITLE")
    @Enumerated(EnumType.STRING)
    private Title title;

    @Column(name="FIRST_NAME")
    private String  fname       = null;

    @Column(name="LAST_NAME")
    private String  lname       = null;

--> Employee.class
@Entity
@Table(name="TBL_EMPLOYEE")
@Audited
public class Employee extends Person {

--> Customer.class
@Entity
@Table(name="TBL_CUSTOMER")
@Audited
public class Customer extends Person {

这很有效，但现在我的问题是:我用一个项目列表扩展了“人”，例如地址/联系信息/等，并对同一类型的所有项目(所有地址)使用一个表.

仅将地址添加到客户时，这没有问题:

--> Customer.java
@OneToMany(cascade = {CascadeType.ALL}, mappedBy="customer")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Address> addresses = null;

--> Address.java
@Entity
@Table(name="TBL_ADDRESSES")
@Audited
public class Address extends PersistentObject {
    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="CUSTOMER_ID")
    private Customer customer;

现在我还想将地址扩展到 Employee。我想，我可以使用 Supertype 来保存地址，但这似乎不起作用:

--> Person.java
@OneToMany(cascade = {CascadeType.ALL}, mappedBy="person")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Address> addresses = null;

--> Address.java
@Entity
@Table(name="TBL_ADDRESSES")
@Audited
public class Address extends PersistentObject {
    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="PERSON_ID")
    private Person person;

运行时，出现以下错误:at.test.Address.person 上的@OneToOne 或@ManyToOne 引用了一个未知实体:at.test.Person

是否有可能让两个实体使用相同的地址表？ ID 不会冲突，因为 Employee 和 Customer 共享相同的序列。或者我应该换一种方式设计这个问题？

非常感谢您，并致以最诚挚的问候!

Answer 1

您必须将您的父类(super class)声明为@Entity 而不是@MappedSuperClass 和单表继承策略，以便您可以在多对一关系中引用它

@Entity
@Table(name="PERSON")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="discriminator",discriminatorType=DiscriminatorType.STRING)
@DiscriminatorValue(value="P")
public abstract class Person {

    @Id
    @GeneratedValue
    @Column(name = "PERSON_ID")
    private Long personId;

    private String firstname;

    private String lastname;

    @OneToMany(cascade = {CascadeType.ALL}, mappedBy="customer")
    @LazyCollection(LazyCollectionOption.FALSE)
    private List<Address> addresses = null;
}

@Entity
@Table(name="PERSON")
@DiscriminatorValue("E")
public class Employee extends Person {

}

@Entity
@Table(name="PERSON")
@DiscriminatorValue("C")
public class Customer extends Person {

}

@Entity
@Table(name="TBL_ADDRESSES")
@Audited
public class Address extends PersistentObject {
     @ManyToOne(fetch=FetchType.LAZY)
     @JoinColumn(name="PERSON_ID")
     private Person person;
}