拥有共享主键的Hibernate拥有实体端

Question

I was reading the following article :

http://websystique.com/hibernate/hibernate-one-to-one-bidirectional-with-shared-primary-key-annotation-example/

and I was confused with two things :

1- who is the owning side of the entity. from the article : "we should tell hibernate that it's the Student class which will manage the relationship."

However the student entity is annotated with mappedBy, and I know that any entity annotated with mappedBy is the inverse side. can anyone please explain this ?

@Entity
@Table(name = "STUDENT")

public class Student {


@Id
@GeneratedValue
@Column(name = "STUDENT_ID")
private long id;

@Column(name = "FIRST_NAME")
private String firstName;

@Column(name = "LAST_NAME")
private String lastName;

@Column(name = "SECTION")
private String section;

@OneToOne(mappedBy="student", cascade = CascadeType.ALL)
private Address address;

2- which ID is the foreign key? the @PrimaryKeyJoinColumn is used in Address entity , is that means the Address Id is the primary and foreign key ? in the following article they have the same example but its unidirectional :

http://websystique.com/hibernate/hibernate-one-to-one-unidirectional-with-shared-primary-key-annotation-example/

you can notice the location of @PrimaryKeyJoinColumn is changed and still the address is the foreign key. which Id will be the foreign key.

Answer 1

1. In this example, Address is indeed the owning side of the association. You're absoluetely right: the side that has the mappedBy attrobute is the inverse side.

2. Since Address is the owner side, and since its ID is also a join column, it should also be a foreign key (just like a join column of a ManyToOne association should also be a FK). Note that this choice means that an address can't exist without a student.