惠州什么是JPA一对一主键连接列？_北大青鸟IT学校

相信学过Java的同学都知道JPA吧！那么，什么是JPA一对一主键连接列呢？下面我们一起跟着惠州北大青鸟老师来学习一下JPA一对一主键连接列。

实例

下面的代码来自Person.java。

package cn.w3cschool.common;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;

@Entitypublic class Person {
 @Id
 @GeneratedValue(strategy=GenerationType.IDENTITY)  private long id;  
 private String name;
 @OneToOne
 @PrimaryKeyJoinColumn  private Department department;  
 public Person() {}  public Person(String name) {
   this.name = name;
 }  public Department getDepartment() {
   return department;
 }  public void setDepartment(Department department) {
   this.department = department;
 }  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;
 }

 @Override  public String toString() {
   return "Person [id=" + id + ", name=" + name + "]";
 }

}

下面的代码来自Department.java。

package cn.w3cschool.common;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;

@Entitypublic class Department {
 @Id
 @GeneratedValue(strategy=GenerationType.IDENTITY)  private long id;  
 private String name;

 @OneToOne(mappedBy="department")
 private Person person;  
 public Person getPerson() {
   return person;
 }  public void setPerson(Person person) {
   this.person = person;
 }  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;
 }
}

下面的代码来自PersonDaoImpl.java。

package cn.w3cschool.common;


import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.springframework.transaction.annotation.Transactional;

@Transactionalpublic class PersonDaoImpl {  public void test(){
   Person p1 = new Person("Tom");
   
   p1.setName("Tom");
   
   Department d = new Department();
   d.setName("Design");
   p1.setDepartment(d);
   d.setPerson(p1);
   
   em.persist(p1);
   em.persist(d);
 }
 @PersistenceContext  private EntityManager em;
}
下载 OneToOne_MappedBy.zip

以下是数据库转储。

Table Name: DEPARTMENT
Row:
   Column Name: ID,
   Column Type: BIGINT:
   Column Value: 1

   Column Name: NAME,
   Column Type: VARCHAR:
   Column Value: Design





Table Name: PERSON
Row:
   Column Name: ID,
   Column Type: BIGINT:
   Column Value: 1

   Column Name: NAME,
   Column Type: VARCHAR:
   Column Value: Tom

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Java

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