jpa双向一对一关联关系

1.1.  关系维护方

Person.java

package com.morris.entity; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToOne; import javax.persistence.Table; @Entity @Table(name="persons") public class Person { @Id @GeneratedValue private Integer personId; @Column(name="person_name",length=50,nullable=false) private String personName; /** * 一对一关联关系配置 * 没有配置mappedBy即为关系维护端 * 配置了optional说明外键不能为空,在另一方也同样不能为空,不需要再配置了 */ @OneToOne(cascade=CascadeType.ALL,fetch=FetchType.EAGER,optional=false) @JoinColumn(name="card_id") private IDCard idCard; public Integer getPersonId() { return personId; } public void setPersonId(Integer personId) { this.personId = personId; } public String getPersonName() { return personName; } public void setPersonName(String personName) { this.personName = personName; } public IDCard getIdCard() { return idCard; } public void setIdCard(IDCard idCard) { this.idCard = idCard; } public Person(Integer personId, String personName, IDCard idCard) { super(); this.personId = personId; this.personName = personName; this.idCard = idCard; } public Person() { super(); // TODO Auto-generated constructor stub } @Override public String toString() { return "Person [personId=" + personId + ", personName=" + personName + ", idCard=" + idCard + "]"; } public Person(String personName) { super(); this.personName = personName; } }

1.2.  关系被维护方

IDCard.java

package com.morris.entity; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.Table; @Entity @Table(name="ID_card") public class IDCard { @Id @GeneratedValue private Integer cardId; @Column(name="card_no",length=18,nullable=false) private String cardNo; /** * 指定了 mappedBy="idCard" 为关系被维护方 */ @OneToOne(cascade={CascadeType.PERSIST,CascadeType.MERGE},fetch=FetchType.EAGER,mappedBy="idCard") private Person person; public IDCard(String cardNo) { super(); this.cardNo = cardNo; } public IDCard() { super(); // TODO Auto-generated constructor stub } public IDCard(String cardNo, Person person) { super(); this.cardNo = cardNo; this.person = person; } @Override public String toString() { return "IDCard [cardId=" + cardId + ", cardNo=" + cardNo + ", person=" + person + "]"; } public Integer getCardId() { return cardId; } public void setCardId(Integer cardId) { this.cardId = cardId; } public String getCardNo() { return cardNo; } public void setCardNo(String cardNo) { this.cardNo = cardNo; } public Person getPerson() { return person; } public void setPerson(Person person) { this.person = person; } }

1.3.  测试

One2OneTest.java

package com.morris.test; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Persistence; import org.junit.AfterClass; import org.junit.BeforeClass; import org.junit.Test; import com.morris.entity.IDCard; import com.morris.entity.Person; public class One2OneTest { private static EntityManagerFactory factory; private static EntityManager manager; @BeforeClass public static void setUpBeforeClass() throws Exception { factory = Persistence.createEntityManagerFactory("jpaDemo"); manager = factory.createEntityManager(); manager.getTransaction().begin(); } @Test public void test() { Person person = new Person("Morris"); IDCard card = new IDCard("123456789"); person.setIdCard(card); manager.persist(person); } @AfterClass public static void setUpAfterClass() throws Exception { manager.getTransaction().commit(); manager.close(); factory.close(); } }