[小知识]Hibernate映射关系小述

Hibernate的映射关系很多，也比较复杂，基本上Hibernate的主要部分就是映射，这里把几个常用的映射介绍一下，以备自己查看。

一、首先是一对多，多对一关联映射，表模型就用公司表和员工表，它们的结构是公司表两个字段：公司编号（自增长），公司名称；员工表三个字段：员工编号（自增长），员工姓名，所属公司编号。

Company.java里面的代码，省略了get和set方法

1 public class Company {
2
3     Company() {
4     }
5
6     private Integer companyId;
7     private String companyName;
8     private Set<User> user;
9
10 ...
11 }

User.java里面的代码，省略get和set方法

1 public class User {
2
3     User() {
4     }
5
6     private Integer UserId;
7     private String userName;
8     private Company company;
9
10 ...
11 }

相关的Hibernate配置文件，Company.hbm.xml

1 <?xml version="1.0" encoding="utf-8"?>
2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
4 <hibernate-mapping package="cn.dy.bean">
5     <class name="Company" table="tb_company" catalog="learn">
6         <id name="companyId" type="integer">
7             <column name="companyId" />
8             <generator class="identity" />
9         </id>
10         <property name="companyName" type="string">
11             <column name="companyName" length="200" not-null="true">
12                 <comment>公司名称</comment>
13             </column>
14         </property>
15         <set name="user">
16             <key column="companyId" />
17             <one-to-many class="User" />
18         </set>
19     </class>
20 </hibernate-mapping>

User.hbm.xml代码为：

1 <?xml version="1.0" encoding="utf-8"?>
2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
4 <hibernate-mapping>
5     <class name="cn.dy.bean.User" table="tb_user" catalog="learn">
6         <id name="userId" type="integer">
7             <column name="userId" />
8             <generator class="identity" />
9         </id>
10         <property name="userName" type="string">
11             <column name="userName" length="16" not-null="true">
12                 <comment>帐号</comment>
13             </column>
14         </property>
15
16         
17         <many-to-one name="company" column="companyId" not-null="true" />
18           </class>
19 </hibernate-mapping>

对应这4段代码，需要注意的是：

一对多配置
1.Company.java里面加入属性Set<User>；
2.Company.hbm.xml文件里面加上set配置，详细见上面代码；
多对一配置

3.User.java里面要加入复杂属性Company；
4.User.java里面不能出现属性companyId；

5.User.hbm.xml文件加上<many-to-one>配置，column为多的那一方表的一个字段，这里是companyId，默认对应公司表的主键。

二、一对一映射，员工表和身份证号码表（编号字段，和员工表员工编号一致；身份证号码字段）

1 public class User {
2
3     User() {
4     }
5
6     private Integer userId;
7     private String userName;
8     private IdCard idCard;
9
10   ...
11 }

IdCard.java代码：

1 public class IdCard{
2
3     IdCard() {
4     }
5
6     private Integer id;
7     private String cardNum;
8     private User user;
9
10   ...
11 }

User.hbm.xml代码

1 <?xml version="1.0" encoding="utf-8"?>
2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
4 <hibernate-mapping>
5     <class name="cn.dy.bean.User" table="tb_user" catalog="learn">
6         <id name="userId" type="integer">
7             <column name="userId" />
8             <generator class="identity" />
9         </id>
10         <property name="userName" type="string">
11             <column name="userName" length="16" not-null="true">
12                 <comment>帐号</comment>
13             </column>
14         </property>
15       <one-to-one name="idCard" />
16           </class>
17 </hibernate-mapping>

IdCard.hbm.xml代码

1 <?xml version="1.0" encoding="utf-8"?>
2 <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
4 <hibernate-mapping>
5     <class name="cn.dy.bean.IdCard" table="tb_idCard" catalog="learn">
6         <id name="id">
7             <generator class="foreign">
8                 <param name="property">user</param>
9             </generator>
10         </id>
11         <property name="cardNum" type="string">
12             <column name="cardName" length="18" not-null="true">
13                 <comment>身份证号码</comment>
14             </column>
15         </property>
16        <one-to-one name="user" />
17     </class>
18 </hibernate-mapping>

三、摘编的其他网站信息：（技术是让使用的，而不是一种桎梏，所以要灵活利用，不能说我使用Hibernate就必须用映射，有时候还要考虑效率问题，具体自己把握吧）

Hibernate 一对一"连接表"双向关联
<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
        <join table="join" optional="true">
         <key column="personId"  unique="true"/>
         <many-to-one name="address" column="addressId" not-null="true" unique="true"/>
        </join>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
        <join table="join" optional="true" inverse="true">
          <key column="addressId" unique="true"/>
          <many-to-one name="person" column="personId" not-null="true" unique="true"/>
        </join>
    </class>
</hibernate-mapping>

Hibernate 一对一"主键"双向关联
<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
        <one-to-one name="address" cascade="all"/>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="foreign">
                <param name="property">person</param>
            </generator>
        </id>
        <property name="addressDetail"/>
        
        <one-to-one name="person" cascade="all" constrained="true"/>
    </class>
</hibernate-mapping>
Hibernate 一对一"外键"双向关联
<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
        <one-to-one name="address" cascade="all" property-ref="person"/>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
        <many-to-one name="person" unique="true"/>
    </class>
</hibernate-mapping>

Hibernate 多对多单向关联

<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
        
        <set name="addresses" table="join" >
           <key column="personId"/>
             <many-to-many  column="addressId" class="cn.dy.Address"/>
        </set>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
    </class>
</hibernate-mapping>
Hibernate 多对一"连接表"单向关联

<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
            <join table="join">
             <key column="personId"/>
            <many-to-one name="address"/>
        </join>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
    </class>
</hibernate-mapping>

Hibernate 多对一外键单向关联

<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
        <many-to-one name="address" column="addressId"/>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
    </class>
</hibernate-mapping>

Hibernate 一对多连接表单向关联

<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
           <set name="addresses" table="join" >
            <key column="personId"/>
            <many-to-many column="addressId" unique="true" class="cn.dy.Address"/>
        </set>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
    </class>
</hibernate-mapping>
Hibernate 一对一主键单向关联

<id name="personId">
<generator class="foreign">
<param name="property">address</param>
</generator>
</id>
<one-to-one name="address" constrained="true"/>
<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId" column="presonid">
         <generator class="foreign">
<param name="property">address</param>
            </generator>
        </id>
        <property name="name"/>
        <property name="age"/>
<one-to-one name="address" constrained="true"/>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
    </class>
</hibernate-mapping>

Hibernate 一对一外键单向关联

<many-to-one name="address" column="addressId" unique="true"/>
<hibernate-mapping>
    <class name="cn.dy.Address" table="ADDRESS">
        <id name="addressId">
            <generator class="identity"/>
        </id>
        <property name="addressDetail"/>
    </class>
</hibernate-mapping>
<hibernate-mapping>
    <class name="cn.dy.Person" table="PERSON">
        <id name="personId">
            <generator class="identity"/>
        </id>
        <property name="name"/>
        <property name="age"/>
        <many-to-one name="address" column="addressId" unique="true"/>
    </class>
</hibernate-mapping>

Hibernate 一对多外键单向关联

Hibernate 一对一连接表单向关联

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发表于 2011-05-30 14:42 DyEnigma 阅读(267) 评论(0) 编辑收藏所属分类: Hibernate

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