使用连接表的单向关联【一对多（one-to-many）】

基于连接表的单向一对多关联 应该优先被采用。请注意，通过指定unique="true"，我们可以把多样性从多对多改变为一对多。

 

 

person.hbm.xml

<?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.lixueli.business.model.Person" table="person">
    <id name="id" column="PERSON_ID">
    	<generator class="native"></generator>
    </id>
    <property name="age"></property>
    <property name="firstName"></property>
    <property name="lastName"></property>
     <set name="events" table="PERSON_EVENT" lazy="false">
     	<key column="PERSON_ID"></key>
     	<many-to-many column="EVENT_ID" class="com.lixueli.business.model.Event" unique="true"></many-to-many>
     </set>
  </class>
  
</hibernate-mapping>

 Event.hbm.xml

<?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.lixueli.business.model.Event" table="event">
  	 <id name="id" column="EVENT_ID">
  	 	<generator class="native" />
  	 </id>
  	 <property name="date" type="timestamp" column="EVENT_DATE"/>
     <property name="title" />
  </class>
  
</hibernate-mapping>

 这样便实现单向一对多关联：一个person可以对应多个Event，但一个Event只能对应一个Person.