hibernate关联关系

hibernate关联映射处理的设计问题

    1：关联方向 Directionality

    2：阶数 Multiplicity

    3：集合 Collection

A:一对一主键单向关联(Person/IdCard)配置文件

    <hibernate-mapping package="com.xyh.hibernate">
        <class name="Person" table="cyy_person">
            <id name="id">
                 <generator class="foreign">
                     <param name="property">card</param>
                 </generator>
            </id>
            <property name="username"></property>

            <!--

                   one-to-one 指示hibernate怎么加载它的关联对象，默认的是根据主键关联加载
                   constrained="true"表明当前主键存在一个约束，person的主键作为外键参照了idCard的主键

                   默认了Casade=“True”属性

            -->
            <one-to-one name="card" constrained="true"></one-to-one>
        </class>
    </hibernate-mapping>

    <hibernate-mapping package="com.xyh.hibernate">
       <class name="IdCard" table="cyy_idcard">
         <id name="id">
               <generator class="native"/>

         </id>
         <property name="cardNo"></property>
     </class>
    </hibernate-mapping>

B:一对一主键双向关联(Person/IdCard)配置文件

    <hibernate-mapping package="com.xyh.hibernate">
        <class name="Person" table="cyy_person">
            <id name="id">
                 <generator class="foreign">
                     <param name="property">card</param>
                 </generator>
            </id>
            <property name="username"></property>

            <!--

                   one-to-one 指示hibernate怎么加载它的关联对象，默认的是根据主键关联加载
                   constrained="true"表明当前主键存在一个约束，person的主键作为外键参照了idCard的主键

                   默认了Casade=“True”属性

            -->
            <one-to-one name="card" constrained="true"></one-to-one>
        </class>
    </hibernate-mapping>

    <hibernate-mapping package="com.xyh.hibernate">
       <class name="IdCard" table="cyy_idcard">
         <id name="id">
               <generator class="native"/>

         </id>
         <property name="cardNo"></property>

         <one-to-one name="person"></one-to-one>
     </class>
    </hibernate-mapping>

C:一对一外键单向关联(Person/IdCard)配置文件

    <hibernate-mapping package="com.xyh.hibernate">
        <class name="Person" table="cyy_person">
          <id name="id">
           <generator class="native"></generator>
          </id>
          <property name="username"></property>
          <many-to-one name="card" unique="true" ></many-to-one>
        </class>
</hibernate-mapping>

<hibernate-mapping package="com.xyh.hibernate">
       <class name="IdCard" table="cyy_idcard">
            <id name="id">
                 <generator class="native"></generator>
            </id>
            <property name="cardNo"></property>
 </class>
</hibernate-mapping>

D:一对一外键双向关联(Person/IdCard)配置文件

 <hibernate-mapping package="com.xyh.hibernate">
         <class name="Person" table="cyy_person">
             <id name="id">
                 <generator class="native"></generator>
              </id>
              <property name="username"></property>

               <!--unique="true"指定唯一参考属性-->
              <many-to-one name="card" unique="true"></many-to-one>
           </class>
</hibernate-mapping>

<hibernate-mapping package="com.xyh.hibernate">
           <class name="IdCard" table="cyy_idcard">
                 <id name="id">
                      <generator class="native"></generator>
                  </id>
                   <property name="cardNo"></property>

                    <!--property-ref 指定外键参考属性-->
                    <one-to-one name="person" property-ref="card"></one-to-one>
             </class>
</hibernate-mapping>

E:多对一关联(Company/Employee)配置文件

   <hibernate-mapping package="com.xyh.hibernate">
        <class name="Company" table="cyy_company">
            <id name="id">
                  <generator class="native"></generator>
            </id>
            <property name="name"></property>
         </class>
   </hibernate-mapping>

   <hibernate-mapping package="com.xyh.hibernate">
          <class name="Employee" table="cyy_employee">
                <id name="id">
                     <generator class="native"></generator>
                </id>
                <property name="name"></property>
                 <many-to-one name="company" column="companyId"></many-to-one>
           </class>
</hibernate-mapping>

 

 

只要处理好对象之间的关系就OK了.