hibernate：继承关系_整个继承树映射到一张表

domain类：
Employee.java

package com.zhaosoft.domain;

public class Employee {

private int id;
private String name;
private Department depart;

public int getId() {
return id;

}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public Department getDepart() {
return depart;
}

public void setDepart(Department depart) {
this.depart = depart;
}

}
两个子类：
sales.java

package com.zhaosoft.domain;

public class Sales extends Employee{

private int sell;//销售额

public int getSell() {
return sell;
}

public void setSell(int sell) {
this.sell = sell;
}
}
Skiller.java

package com.zhaosoft.domain;

public class Skiller extends Employee{
private String skill;

public String getSkill() {
return skill;
}

public void setSkill(String skill) {
this.skill = skill;
}

}
映射文件：
<?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.zhaosoft.domain">
<!-- 当discriminator-value值为0时，为普通员工 -->
<class name="Employee" discriminator-value="0">
<id name="id">
<!-- 表示主键为自动增长 -->
<generator class="native"/>
</id>
<!-- 鉴别器，区分是那一种子类 -->
<discriminator column="type" type="int"/>
<property name="name" type="string"/>
<many-to-one name="depart" class="Department" column="depart_id"></many-to-one>
<!-- 当为1时，为技术人员 -->
<subclass name="Skiller" discriminator-value="1">
<property name="skill"></property>
</subclass>
<!-- 当为2时为销售人员 -->
<subclass name="Sales" discriminator-value="2">
<property name="sell"></property>
</subclass>
</class>
</hibernate-mapping>
测试：

package com.zhaosoft.test;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.hibernate.Hibernate;
import org.hibernate.Session;
import org.hibernate.Transaction;

import com.zhaosoft.domain.Department;
import com.zhaosoft.domain.Employee;
import com.zhaosoft.domain.Sales;
import com.zhaosoft.domain.Skiller;
import com.zhaosoft.hibernate.HibernateUtil;

public class Many2One {
public static void main(String[] args) {
add();
//queryDepartment(1);
//queryEmployee(1);
}

public static void queryDepartment(int id) {
Session s = HibernateUtil.getSession();
try {
Transaction t = s.beginTransaction();
t.begin();
Department de = (Department) s.get(Department.class, 1);

t.commit();
Hibernate.initialize(de.getEmps());
System.out.println(de.getName());
Set<Employee> set=de.getEmps(); //加载数据
Iterator<Employee> it=set.iterator();
while(it.hasNext()){
Employee employee= it.next();
System.out.println(employee.getName());
}

} catch (Exception e) {

} finally {
if (s != null) {
s.close();
}
}

}

public static Employee queryEmployee(int id) {

Session s = null;
Transaction tx=null;
try {

s=HibernateUtil.getSession();
tx=s.beginTransaction();
Employee emp=(Employee)s.get(Employee.class,id);
//Hibernate.initialize(emp.getDepart());
tx.commit();
return emp;
} finally {
if (s != null) {
s.close();
}
}

}

public static void add() {
Session s = null;
Transaction t=null;
try {
s=HibernateUtil.getSession();
t = s.beginTransaction();
t.begin();
Department d = new Department();
d.setName("销售部");

Employee employee1 = new Employee();
employee1.setName("小三");
employee1.setDepart(d);

Skiller employee2 = new Skiller();
employee2.setName("李斯");
employee2.setSkill("skill");
employee2.setDepart(d);

Sales employee3 = new Sales();
employee3.setName("王五");
employee3.setSell(100);
employee3.setDepart(d);

Set<Employee> set=new HashSet<Employee>();
set.add(employee1);
set.add(employee2);
set.add(employee3);
d.setEmps(set);
s.save(d);
s.save(employee1);
s.save(employee2);
s.save(employee3);

t.commit();
} catch (Exception e) {

} finally {
if (s != null) {
s.close();
}
}
}
}