07讲、JPA中的一对一双向关联

最新推荐文章于 2024-02-26 22:18:48 发布

转载最新推荐文章于 2024-02-26 22:18:48 发布 · 60 阅读

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原文链接：http://www.cnblogs.com/kaisheng0777/archive/2013/02/22/2921940.html

本文介绍了一对一关联映射的实现方式，通过Person和IDCard两个实体类展示了如何在Java环境下使用JPA进行实体间的一对一关联。文章包含完整的实体类定义及测试用例，有助于理解实体关系映射。

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package cn.itcast.bean;

import javax.persistence.CascadeType;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.OneToOne;

//关系被维护端，没有权利去修改外键

@Entity

public class IDCard {

private Long id;

private String cardno;

private Person person;

public IDCard(){}

public IDCard(String cardno) {

this.cardno = cardno;

}

@Id @GeneratedValue

public Long getId() {

return id;

}

public void setId(Long id) {

this.id = id;

}

@Column(length=18,nullable=false)

public String getCardno() {

return cardno;

}

public void setCardno(String cardno) {

this.cardno = cardno;

}

@OneToOne(mappedBy="idCard",cascade={CascadeType.PERSIST,CascadeType.MERGE,CascadeType.REFRESH})

public Person getPerson() {

return person;

}

public void setPerson(Person person) {

this.person = person;

}

package cn.itcast.bean;

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;

@Entity

public class Person {

private Long id;

private String name;

private IDCard idCard;

public Person(){}

public Person(String name) {

this.name = name;

}

@Id @GeneratedValue

public Long getId() {

return id;

}

public void setId(Long id) {

this.id = id;

}

@Column(length=10,nullable=false)

public String getName() {

return name;

}

public void setName(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;

}

package junit.test;

import javax.persistence.EntityManager;

import javax.persistence.EntityManagerFactory;

import javax.persistence.Persistence;

import org.junit.BeforeClass;

import org.junit.Test;

import cn.itcast.bean.IDCard;

import cn.itcast.bean.Person;

public class OneToOneTest {

@BeforeClass

public static void setUpBeforeClass() throws Exception {

}

@Test public void save(){

EntityManagerFactory factory = Persistence.createEntityManagerFactory("itcast");

EntityManager em = factory.createEntityManager();

em.getTransaction().begin();

Person person = new Person("老张");

person.setIdCard(new IDCard("111112222233333444"));

em.persist(person);

em.getTransaction().commit();

em.close();

factory.close();

}

转载于:https://www.cnblogs.com/kaisheng0777/archive/2013/02/22/2921940.html