you see,in Hibernate,we can set a pojo to have an one-to-one relationship with the other entity by share their primary key,for example:
<class name="TUser" table="user" ...... <one-to-one name="passport" class="TPassport" cascade="all" outer-join="all" /> </class>
<class name="TPassport" table="user" > <id name="id" column="id"> <generator class="foreign"> <param name="property>user</param> </generator> </id> <one-to-one name="user" class="TUser" contrained="true" />