Hibernate 一对一主键双向关联

Hibernate 一对一主键双向关联

一对一主键映射在一对一映射中还算是最为常用的。

一、模型

一个人Person 对应一个地址Address。

二、数据模型和对象模型图



导出建表SQL如下：

/*==============================================================*/
/* DBMS name:            MySQL 5.0                                                                        */
/* Created on:         2008-12-8 23:05:32                                                     */
/*==============================================================*/


drop table if exists address;

drop table if exists person;

/*==============================================================*/
/* Table: address                                                                                             */
/*==============================================================*/
create table address
(
     id                                     bigint not null comment 'ID',
     detail                             varchar(120) not null comment '详细地址',
     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_2 foreign key (id)
            references person (id) on delete restrict on update restrict;

三、对象模型代码

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;

四、映射代码
<?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>
    <!-- cascade="all"：在保存person对象的时候，级联保存person对象关联的address对象    -->
    <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="mydb">
    <id name="id" type="java.lang.Long">
      <column name="id" />
      <!-- class="foreign": 一对一主键映射中，使用另外一个相关联的对象的标识符 -->
      <generator class="foreign">
        <param name="property">person</param>
      </generator>
    </id>
    <property name="detail" type="java.lang.String">
      <column name="detail" length="120" not-null="true">
        <comment>详细地址</comment>
      </column>
    </property>
    <!-- 表示在address表存在一个外键约束，外键参考相关联的表person -->
    <one-to-one name="person" constrained="true" />
  </class>
</hibernate-mapping>

五、Hibernate配置
<?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/mydb
  </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>

测试很简单就不写了。

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