关于Hibernate的关联关系及其操作

<hibernate-mapping>
        <class name="hibernate.Customer" table="customer" schema="dbo" catalog="test">
        <id name="id" type="java.lang.Long">
            <column name="id" />
            <generator class="uuid.hex" />
        </id>
        <!--映射对应的身份对象-->
        <one-to-one name="Certificate" class="hibernate.Certificate" 
       update="true" insert="true" fetch="select" cascade="all"/>
        <property name="name" type="java.lang.String">
        <column name="name" length="50" not-null="true" />
        </property>
        </class>
</hibernate-mapping>

<hibernate-mapping>
<class name="hibernate.Certificate" table="certificate" schema="dbo" catalog="test">
<id name="id" type="java.lang.Long">
<column name="id" />
<!—引用Customer的主键作为Certificate的主键和外键-->
<generator class="foreign" />
<param name="property">Customer</param>
</generator>
</id>
<property name="information" type="java.lang.String">
<column name="information" length="50" not-null="true" />
</property>
<one-to-one name="Customer" class="hibernate.Customer"
constrained="true"<!—表示Certificate引用了Customer主键作外键-->
</class>
</hibernate-mapping>