Hibernate学习笔记-------继承关系映射

继承关系映射配置实例------------>

<?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 package="com.xx.domain">

	<!-- 继承关系之映射成一张表 -->
	<!-- 父类的也必须加上discriminator-value属性 -->
	<class name="Animal" table="t_animal" discriminator-value="0">
		<id name="id">
			<generator class="native" />
		</id>
		<discriminator column="type" type="int"/>
		<property name="name"/>
		<subclass name="Pepole" discriminator-value="1">
			<property name="sex" ></property>
		</subclass>
		<subclass name="Dog" discriminator-value="2">
			<property name="age" ></property>
		</subclass>
	</class>
	 <!-- 继承关系之每个子类映射成一张表 -->
	 <!-- 
	<class name="Animal" table="t_animal">
		<id name="id">
			<generator class="native" />
		</id>
		<property name="name"/>
		<joined-subclass name="Pepole">
			<key column="animalid"/>
			<property name="sex"></property>
		</joined-subclass>
		<joined-subclass name="Dog">
			<key column="animalid"/>
			<property name="age"></property>
		</joined-subclass>
	</class>
	 -->
	<!-- 继承关系之鉴别器与内连接相结合 -->
	<!--  
	<class name="Animal" table="t_animal" discriminator-value="0">
		<id name="id">
			<generator class="native" />
		</id>
		<discriminator column="type" type="int"/>
		<property name="name"/>
		<subclass name="Pepole" discriminator-value="1">
			<property name="sex" ></property>
		</subclass>
		
		<subclass name="Dog" discriminator-value="2">
			<join table="dog">
				<key column="anmimalid"/>
				<property name="age" ></property>
			</join>
		</subclass>
	</class>
	-->
	<!-- 每个具体类映射一张独立表 -->
	<!-- 子类的表和父类的表的id不能重复，所以不能用自增 -->
	<!-- 
	<class name="Animal" table="t_animal">
		<id name="id">
			<generator class="hilo" />
		</id>
		<property name="name"/>
		<union-subclass name="Pepole">
			<property name="sex"/>		
		</union-subclass>
		<union-subclass name="Dog">
			<property name="age"/>		
		</union-subclass>
	</class>
	 -->
</hibernate-mapping>