一对一关系
@Entity @Table(name="person_one") public class Person { private Integer id; private String name; private IDCard idcard; @OneToOne(cascade={CascadeType.ALL},optional=false) @JoinColumn(name="idcard_id") public IDCard getIdcard() { return idcard; } public void setIdcard(IDCard idcard) { this.idcard = idcard; } @Id @GeneratedValue public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } @Column(length=12,nullable=false) public String getName() { return name; } public void setName(String name) { this.name = name; } } @Entity @Table(name="idcard_one") public class IDCard { private Integer id; private String cardno; private Person person; @OneToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH} ,mappedBy="idcard") public Person getPerson() { return person; } public void setPerson(Person person) { this.person = person; } @Id @GeneratedValue public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } @Column(length=18,nullable=false) public String getCardno() { return cardno; } public void setCardno(String cardno) { this.cardno = cardno; } }