Hibernate 一对一外键双向关联

 一对一外键关联是一对多外键关联的特例，只是在多的一方加了个唯一性约束。

 

一、模型

一个人对应一个地址。

 

/*==============================================================*/
/* DBMS name:      MySQL 5.0                                    */
/* Created on:     2008-12-9 0:12:54                            */
/*==============================================================*/

drop table if exists address;

drop table if exists person;

/*==============================================================*/
/* Table: address                                               */
/*==============================================================*/
create table address
(
   id                   bigint not null auto_increment comment 'ID',
   detail               varchar(120) not null comment '详细地址',
   personid             bigint comment '人的ID',
   primary key (id)
)
type = InnoDB;

alter table address comment '地址';

/*==============================================================*/
/* Table: person                                                */
/*==============================================================*/
create table person
(
   id                   bigint not null auto_increment comment 'ID',
   name                 varchar(24) not null comment '姓名',
   primary key (id)
)
type = InnoDB;

alter table person comment '人';

alter table address add constraint FK_Reference_4 foreign key (personid)
      references person (id) on delete restrict on update restrict;

 

 

二、对象模型

 

public class Person implements java.io.Serializable {

   private Long id;
   private String name;
   private Address address;

 

public class Address implements java.io.Serializable {
   private Long id;
   private Person person;
   private String detail;

 

三、映射文件

<? xml version ="1.0" encoding ="utf-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

< hibernate-mapping >
   < class name ="entity.Person" table ="person" >
     < id name ="id" type ="java.lang.Long" >
       < column name ="id" />
       < generator class ="identity" />
     </ id >
     < property name ="name" type ="java.lang.String" >
       < column name ="name" length ="24" not-null ="true" >
         < comment >姓名 </ comment >
       </ column >
     </ property >
     < one-to-one name ="address" cascade ="all" />
   </ class >
</ hibernate-mapping >

 

<? xml version ="1.0" encoding ="utf-8" ?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

< hibernate-mapping >
   < class name ="entity.Address" table ="address" catalog ="testdb" >
     < id name ="id" type ="java.lang.Long" >
       < column name ="id" />
       < generator class ="identity" />
     </ id >
     < property name ="detail" type ="java.lang.String" >
       < column name ="detail" length ="120" not-null ="true" >
         < comment >详细地址 </ comment >
       </ column >
     </ property >
     < many-to-one name ="person" class ="entity.Person"
       fetch ="select" unique ="true" >
       < column name ="personid" >
         < comment >人的ID </ comment >
       </ column >
     </ many-to-one >
   </ class >
</ hibernate-mapping >

 

<? xml version ='1.0' encoding ='UTF-8' ?>
<!DOCTYPE hibernate-configuration PUBLIC
                    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                                     -->
< hibernate-configuration >

   < session-factory >
     < property name ="connection.username" >root </ property >
     < property name ="connection.url" >
      jdbc:mysql://localhost:3306/testdb
     </ property >
     < property name ="dialect" >
      org.hibernate.dialect.MySQLDialect
     </ property >
     < property name ="connection.password" >xiaohui </ property >
     < property name ="connection.driver_class" >
      com.mysql.jdbc.Driver
     </ property >
     < property name ="show_sql" >true </ property >
     < property name ="format_sql" >true </ property >
     < mapping resource ="entity/Person.hbm.xml" />
     < mapping resource ="entity/Address.hbm.xml" />

   </ session-factory >

</ hibernate-configuration >

 

四、测试

import org.hibernate.Transaction;

import entity.Address;
import entity.Person;

import utils.HibernateSessionFactory;

public class Test {
   public static void main(String[] args) {
    savePerson();
  }

   public static void savePerson() {
    Person person = new Person( "张三");
    Address address = new Address( "XX街X号");
    person.setAddress(address);
    address.setPerson(person);

    Session session = HibernateSessionFactory.getSession();
    Transaction tx = session.beginTransaction();
    session.save(person);
    tx.commit();
  }
}

 

运行日志：

Hibernate:    
         insert    
         into
                person
                ( name)    
         values
                (?)
Hibernate:    
         insert    
         into
                testdb.address
                (detail, personid)    
         values
                (?, ?)