JPA 系列教程8-双向一对一共享主键

双向一对一共享主键的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,

  `cardNo` varchar(18) DEFAULT NULL,

  PRIMARY KEY (`id`),

  CONSTRAINT `FK_kq6it0i1ktl2w8mc9hifq4ov3` FOREIGN KEY (`id`) REFERENCES `t_person` (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Person

package com.jege.jpa.one2one;

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 [email protected]

 * @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", 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.OneToOne;

import javax.persistence.PrimaryKeyJoinColumn;

import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

import org.hibernate.annotations.Parameter;

/**

 * @author JE哥

 * @email [email protected]

 * @description:关系被维护端,共享主键

 */

@Entity

@Table(name = "t_idcard")

public class IdCard {

  @Id

  @GeneratedValue(generator = "pkGenerator")

  @GenericGenerator(name = "pkGenerator", strategy = "foreign", parameters = @Parameter(name = "property", value = "person"))

  private Long id;

  @Column(length = 18)

  private String cardNo;

  @OneToOne(optional = false, fetch = FetchType.LAZY)

  // 如果不加这个注解，添加t_idcard信息时，就会自动在t_idcard表中增加了一个外键person_id

  @PrimaryKeyJoinColumn

  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 [email protected]

 * @description:一对一 共享主键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.persist(idCard);

    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();

  }

}

源码地址

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

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