JPA 菜鸟教程 9 双向一对一唯一外键

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双向一对一唯一外键的ddl语句

CREATE TABLE `t_person` (  `id` bigint(20) NOT NULL AUTO_INCREMENT,  `name` varchar(255) DEFAULT NULL,  PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;CREATE TABLE `t_idcard` (  `id` bigint(20) NOT NULL AUTO_INCREMENT,  `cardNo` varchar(18) DEFAULT NULL,  `person_id` bigint(20) NOT NULL,  PRIMARY KEY (`id`),  UNIQUE KEY `UK_f1wp2l5dnl1w6sprob8ocil2t` (`person_id`),  CONSTRAINT `FK_f1wp2l5dnl1w6sprob8ocil2t` FOREIGN KEY (`person_id`) REFERENCES `t_person` (`id`)) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;

Person

package com.jege.jpa.one2one;import javax.persistence.CascadeType;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.Id;import javax.persistence.OneToOne;import javax.persistence.Table;/** * @author JE哥 * @email [e-mail] * @description:关系维护端 */@Entity@Table(name = "t_person")public class Person {  @Id  @GeneratedValue  private Long id;  private String name;  // mappedBy配置映射关系:当前对象IdCard属于哪个person对象  @OneToOne(optional = false, mappedBy = "person", cascade = CascadeType.ALL, fetch = FetchType.LAZY)  private IdCard idCard;  public Long getId() {    return id;  }  public void setId(Long id) {    this.id = id;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public IdCard getIdCard() {    return idCard;  }  public void setIdCard(IdCard idCard) {    this.idCard = idCard;  }}

IdCard

package com.jege.jpa.one2one;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;/** * @author JE哥 * @email [e-mail] * @description:关系被维护端,多表(唯一unique = true) */@Entity@Table(name = "t_idcard")public class IdCard {  @Id  @GeneratedValue  private Long id;  @Column(length = 18)  private String cardNo;  // 默认值optional = true表示idcard_id可以为空;反之。。。  @OneToOne(optional = false, fetch = FetchType.LAZY)  @JoinColumn(name = "person_id", unique = true)  // unique=true确保了一对一关系  private Person person;  public Long getId() {    return id;  }  public void setId(Long id) {    this.id = id;  }  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;  }}

One2OneTest

package com.jege.jpa.one2one;import javax.persistence.EntityManager;import javax.persistence.EntityManagerFactory;import javax.persistence.Persistence;import org.junit.After;import org.junit.AfterClass;import org.junit.Before;import org.junit.BeforeClass;import org.junit.Test;/** * @author JE哥 * @email [e-mail] * @description:一对一CRUD Test */public class One2OneTest {  private static EntityManagerFactory entityManagerFactory = null;  private EntityManager entityManager = null;  @BeforeClass  public static void setUpBeforeClass() throws Exception {    entityManagerFactory = Persistence.createEntityManagerFactory("com.jege.jpa");  }  @Before  public void setUp() throws Exception {    entityManager = entityManagerFactory.createEntityManager();  }  // 级联保存  @Test  public void persist() throws Exception {    Person person = new Person();    person.setName("jege");    IdCard idCard = new IdCard();    idCard.setCardNo("123456789123456789");    person.setIdCard(idCard);    idCard.setPerson(person);    entityManager.getTransaction().begin();    entityManager.persist(person);    entityManager.getTransaction().commit();  }  @Test  public void find() throws Exception {    persist();    entityManager.clear();    Person person = entityManager.find(Person.class, 1L);    System.out.println(person.getName());    System.out.println("-----------------");    System.out.println(person.getIdCard().getCardNo());  }  @Test  public void find1() throws Exception {    persist();    entityManager.clear();    IdCard idCard = entityManager.find(IdCard.class, 1L);    System.out.println(idCard.getCardNo());    System.out.println("-----------------");    System.out.println(idCard.getPerson().getName());  }  @After  public void tearDown() throws Exception {    if (entityManager != null && entityManager.isOpen())      entityManager.close();  }  @AfterClass  public static void tearDownAfterClass() throws Exception {    if (entityManagerFactory != null && entityManagerFactory.isOpen())      entityManagerFactory.close();  }}

其他关联项目

• JPA 菜鸟教程 8 双向一对一共享主键
  http://blog.csdn.net/je_ge/article/details/53495313

源码地址

https://github.com/je-ge/jpa

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