继承关系（一张表）

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本文介绍了一种使用Java Hibernate框架实现的员工类别与部门管理方案，包括员工技能、销售等不同类型的员工及其与部门之间的关联关系。通过继承方式定义了不同类型的员工，并详细展示了如何在Hibernate中配置这些关系。

employee
字段名	主键	类型	描述
id	pk	int	员工编号
name		varchar(50)	员工姓名
department_id	fk	int	所属部门编号
type		int	所属员工类型
skill		varchar(50)	技能员工（type=1）
sell		int	销售员工（type=2）

package domain;

import java.util.Set;

public class Department {
	private int id;
	private String name;
	private Set<Employee> emps;
	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 Set<Employee> getEmps() {
		return emps;
	}
	public void setEmps(Set<Employee> emps) {
		this.emps = emps;
	}
	
	
	
}

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
  
<hibernate-mapping package="domain">
	<class name="Department" table="`department`">
	  	<id name="id" column="`id`">
	  	  <generator class="native"></generator>
	  	</id>
	  	<properties name="name"></properties>
	  	<set name="emps">
	  		<key column="depart_id"></key>
	  		<one-to-many class="Employee"/>
	  	</set>
	  	</class>
</hibernate-mapping>

package domain;

public class Employee {
	private int id;
	private String name;
	private Department department;
	
	public Department getDepartment() {
		return department;
	}
	public void setDepartment(Department department) {
		this.department = department;
	}
	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;
	}
	

}

package domain;

public class Sales extends Employee {
	private int sell;

	public int getSell() {
		return sell;
	}

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

}

package domain;

public class Skiller extends Employee {

	private String skill;

	public String getSkill() {
		return skill;
	}

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

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping SYSTEM
  "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
  
<hibernate-mapping package="domain">
	<class name="Employee" table="`employee`" discriminator-value="0">
	  	<id name="id" column="`id`">
	  	  <generator class="native"></generator>
	  	</id>
	  	<discriminator column="type" type="int"></discriminator>
	  	<properties name="name"></properties>
	  	<many-to-one name="department" column="depart_id"></many-to-one>
	  	<subclass name="Skiller" discriminator-value="1">
	  		<property name="skill"></property>
	  	</subclass>
	  	<subclass name="Sales" discriminator-value="2">
	  		<property name="sell"></property>
	  	</subclass>
	  	</class>
</hibernate-mapping>

测试：

package test;

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

import org.hibernate.Transaction;
import org.hibernate.classic.Session;

import dao.HibernateUtil;
import domain.Department;
import domain.Employee;
import domain.Sales;
import domain.Skiller;

public class Extends {
	public static void main(String[] args) {
		add();
	}
	static void  add(){
	Session session = null;
	Transaction tx = null;
	try {
		Department depart = new Department();
		depart.setName("depart name 1");
		
		Employee emp1 = new Employee();
		emp1.setName("emp1");
		emp1.setDepartment(depart);
		
		
		Skiller emp2 = new Skiller();
		emp2.setName("emp2");
		emp2.setSkill("skill");
		emp2.setDepartment(depart);
		
	    Sales emp3 = new Sales();
		emp3.setName("emp3");
		emp3.setDepartment(depart);
		emp3.setSell(100);
		
		Set<Employee> emps = new HashSet<Employee>();
		emps.add(emp1);
		emps.add(emp2);
		emps.add(emp3);
		
		depart.setEmps(emps);
		session = (Session) HibernateUtil.getSession();
		tx = session.beginTransaction();
		session.save(depart);
		session.save(emps);
		tx.commit();
		
	} catch (Exception e) {
		// TODO: handle exception
	}finally{
		if(session != null){
			session.close();
		}
	}
}
}