java - Hibernate映射文件中discriminator-value的含义是什么？

Question

<class name="admin.model.OrganizationUnit" table="ORGANIZATION_UNIT" discriminator-value="admin.model.OrganizationUnit" dynamic-update="true">

    <id name="ObjectId" type="string" column="object_id">
        <generator class="assigned"/>
    </id>
    <discriminator column="discriminator"/>
    <property name="ObjectType" type="string">
        <column name="ObjectType" sql-type="varchar2(255)" not-null="true"/>
    </property>

    <subclass name="admin.model.DmSystem" discriminator-value="admin.model.DmSystem" dynamic-update="true">

        <set name="ChildOrgs" lazy="true" table="ORGANIZATION_UNIT" where="ou_type_code='CWORG'">
            <key column="system_org_id"/>
            <one-to-many class="Dm.bizcomponent.admin.model.OrganizationUnit"/>
        </set>

        <set name="SystemAdminAccessGroup" lazy="true" inverse="true" table="CWGROUP" where="group_type_code='SYSTEM_ADMINACCESS'">
            <key column="owner_id"/>
            <one-to-many class="admin.model.Group"/>
        </set>
    </subclass>
</class>

这是映射代码在上面的代码中有一个父类OrganizationUnit和两个子类

Answer 1

鉴别器值用于确定与基类数据库表中给定数据库行条目相关联的实体子类类型的类类型。