hibernate中一对一关系，互存对方主键为外键的映射文件

card.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    
    <hibernate-mapping package="com.kaishengit.pojo">
    	<class name="Card" table="t_card">
    		<id name="id" column="id">
    			<generator class="native"></generator>
    		</id>
    		<property name="cardnum" column="cardnum"></property>
                <!-- 
			name : 在类中一这一端的对象的属性名
			class : name的类型(要和package拼成一个类的完全限定名)
			column : 外键
		 -->
			
	        <many-to-one name="user" class="User" column="user_id" unique="true"></many-to-one>    		
    	</class>
    </hibernate-mapping>

user.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
    
    <hibernate-mapping package="com.kaishengit.pojo">
    	<class name="User" table="t_user">
    		<id name="id" column="user_id">
    			<generator class="native"></generator>
    		</id>
    		<property name="name" column="user_name"></property>
    		<property name="password" column="user_password"></property>
			<many-to-one name="card" class="Card" column="card_id" unique="true"></many-to-one>
    	</class>
    </hibernate-mapping>