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JPA学习---第十节：JPA中的一对一双向关联
1、创建实体类，代码如下：
代码清单1：
package learn.jpa.entity;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.JoinColumn;import javax.persistence.OneToOne;@Entitypublic class Person { private int id; private String name; private IDCard idcard; public Person(){ } public Person(String name){ this.name = name; } @OneToOne(optional=false,cascade=CascadeType.ALL) @JoinColumn(name="idcard_id") public IDCard getIdcard() { return idcard; } public void setIdcard(IDCard idcard) { this.idcard = idcard; } @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } @Column(length=10,nullable=false) public String getName() { return name; } public void setName(String name) { this.name = name; }}
代码清单2：
package learn.jpa.entity;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.OneToOne;@Entitypublic class IDCard { private int id; private String cardno; private Person person; public IDCard(){ } public IDCard(String cardno){ this.cardno = cardno; } @OneToOne(mappedBy="idcard",cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH}, optional=false) public Person getPerson() { return person; } public void setPerson(Person person) { this.person = person; } @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } @Column(length=18, nullable=false) public String getCardno() { return cardno; } public void setCardno(String cardno) { this.cardno = cardno; } }
2、测试代码：
package learn.jpa.test;import static org.junit.Assert.*;import javax.persistence.EntityManager;import javax.persistence.EntityManagerFactory;import javax.persistence.Persistence;import learn.jpa.entity.IDCard;import learn.jpa.entity.Person;import org.junit.Test;public class OneToOneTest { /** * 测试数据库是否可以生成表 */ @Test public void test() { EntityManagerFactory factory = Persistence.createEntityManagerFactory("learn_jpa"); factory.close(); } @Test public void save(){ EntityManagerFactory factory = Persistence.createEntityManagerFactory("learn_jpa"); EntityManager em = factory.createEntityManager(); em.getTransaction().begin(); // 开启事务 Person person = new Person("hwl"); IDCard idcard = new IDCard("435034189809170123"); idcard.setPerson(person); person.setIdcard(idcard); em.persist(person); em.getTransaction().commit(); em.close(); factory.close(); }}
JPA学习---第十节：JPA中的一对一双向关联
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