one to one 主键关联

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.bjsxt.hibernate.Person" table="t_person">
		<id name="id">
			<generator class="foreign">
				<param name="property">idCard</param>
			</generator>
		</id>
		<property name="name"/>
		<one-to-one name="idCard" constrained="true"/>
	</class>
</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.bjsxt.hibernate.IdCard" table="t_idcard">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="cardNo"/>
		<one-to-one name="person"/>
	</class>
</hibernate-mapping>

单向

hibernate一对一主键关联映射（单向关联Person---->IdCard）

一对一主键关联映射:让两个实体对象的id保持相同，这样可以避免多余的字段被创建

具体映射：

 <id name="id">
  <!-- person的主键来源idCard，也就是共享idCard的主键 -->
  <generator class="foreign">
   <param name="property">idCard</param>
  </generator>
 </id>
 <property name="name"/>
 <!-- one-to-one标签的含义，指示hibernate怎么加载它的关联对象，默认根据主键加载，
 constrained="true"， 表明当前主键上存在一个约束，person的主键作为外键参照了idCard 
  -->
 <one-to-one name="idCard" constrained="true"/>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.yelang.hibernate.IdCard" table="t_idcard">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="cardNo"/>
	</class>
</hibernate-mapping>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC 
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.bjsxt.hibernate.Person" table="t_person">
		<id name="id">
			<generator class="foreign">
				<param name="property">idCard</param>
			</generator>
		</id>
		<property name="name"/>
		<one-to-one name="idCard" constrained="true"/>
	</class>
</hibernate-mapping>