Hibernate一对一主键关联（基于annotation注解方式)

hibernate中一对一的关联有两种方式：一种是采用外键关联，另外一种是采用主键关联。

  最近项目中用到一对一主键双向关联，并且是基于注解的方式。期间遇到一些问题，现在贴出来探讨探讨。

  一个丈夫(husband)对应一个妻子(wife)，主要目标是在存储丈夫或者妻子时，关联的对象也被存储。具体代码如下：

  husband类： 

package cn.edu.dlnu.resources.model.entity;

import javax.persistence.CascadeType;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.OneToOne;

import javax.persistence.PrimaryKeyJoinColumn;

@Entity

public class Husband {

 private int id;

 private String name;

 private Wife wife;

 @Id

 @GeneratedValue //主键生成器
 public int getId() {

  return id;

 }

 public String getName() {

  return name;

 }
 @OneToOne(cascade=CascadeType.ALL)

 @PrimaryKeyJoinColumn//这个注解只能写在主(生成ID)的一端
 public Wife getWife() {

  return wife;

 }

 public void setId(int id) {

  this.id = id;

 }

 public void setName(String name) {

  this.name = name;

 }

 public void setWife(Wife wife) {

  this.wife = wife;

 }

}

  wife类：

package cn.edu.dlnu.resources.model.entity;

import javax.persistence.CascadeType;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

import javax.persistence.OneToOne;

import org.hibernate.annotations.GenericGenerator;

import org.hibernate.annotations.Parameter;

@Entity

public class Wife {

 private int id;

 private String name;

 private Husband husband;

 
 @Id

 @GenericGenerator(name ="pkGenerator",strategy="foreign" ,parameters={@Parameter(name="property",value="husband")})

    @GeneratedValue(generator="pkGenerator")

//wife的ID是根据husband的ID来赋值的，这里需要设置ID生成器的策略为foreign，参数中指定wife的ID是使用husband对象中的ID
 public int getId() {

  return id;

 }

 public void setId(int id) {

  this.id = id;

 }

 public String getName() {

  return name;

 }

 public void setName(String name) {

  this.name = name;

 }

 public void setHusband(Husband husband) {

  this.husband = husband;

 }

 @OneToOne(cascade=CascadeType.ALL, mappedBy="wife")

 public Husband getHusband() {

  return husband;

 }

}

  OneToOnePKTest类：

package cn.edu.dlnu.resources.model.entity;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

import cn.edu.dlnu.resources.model.entity.Husband;

import cn.edu.dlnu.resources.model.entity.Wife;

public class OneToOnePKTest {

 private static SessionFactory sessionFactory;

 

 @BeforeClass

 public static void beforeClass() {

   sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();

 }

 @AfterClass

 public static void afterClass() {

  sessionFactory.close();

 }

 

 @Test

 public void testSave(){

  Session s = sessionFactory.getCurrentSession();

  s.beginTransaction();

  

  Husband h = new Husband();

  Wife w = new Wife();

  w.setName("w");

  h.setName("h");

  h.setWife(w);

  w.setHusband(h);
  s.save(w);

  s.getTransaction().commit();

 }

@Test

 public void testSchemaExport() {

  new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

 }

 public static void main(String[] args) {

  beforeClass();

  new OneToOnePKTest().testSave();

  afterClass();

 }

}

hibernate生成的数据库表：create table Husband (

        id integer not null auto_increment,

        name varchar(255),

        primary key (id)

    )；

create table Wife (

        id integer not null,

        name varchar(255),

        primary key (id)

    )

运行testSave()，方法后数据库中husband 与 wife表中记录的主键一致。

 转自：点击打开链接