hibernate继承映射之每个分层结构一张表

Person
private int id;
private String name;
private int age;
private String sex;
private String type;

Student extends Person
private String school;

Worker extends Person
private String factory;

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.skuedu.bean">
<class name="Person" table="person">
<id name="id" >
<generator class="native"></generator>
</id>
<discriminator column="type" type="string" not-null="true"></discriminator>
<property name="name"  length="30"></property>
<property name="age"   ></property>
<property name="sex"  length="10"></property>
<subclass name="Student" discriminator-value="STUDENT">
<property name="school"></property>
</subclass>
<subclass name="Worker" discriminator-value="WORKER">
<property name="factory"></property>
</subclass>
</class>
</hibernate-mapping>