一对多关联映射-优快云博客

本文介绍了一种通过Java实体类实现部门与员工之间的一对多关系映射的方法，并提供了具体的部门和员工类定义及相应的Hibernate XML映射文件示例。

例如：部门与员工的关系（部门中存在一个员工集合的引用）

部门

package com.chris.entity;

import java.util.Set;

/**
 * 部门
 * @author Administrator
 *
 */
public class Department {

	private int id;
	private String name;
	private Set<Employee> employees;
	
	public Set<Employee> getEmployees() {
		return employees;
	}
	public void setEmployees(Set<Employee> employees) {
		this.employees = employees;
	}
	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;
	}
}

员工

package com.chris.entity;

/**
 * 员工
 * @author Administrator
 *
 */
public class Employee {

	private int id;
	private String name;

	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;
	}
}

员工映射文件：

<?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.chris.entity">
	
	<class name="Employee">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
	</class>
</hibernate-mappin

部门映射文件：

<?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.chris.entity">
	
	<class name="Department">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name" unique="true"/>
		<set name="employees">
			<!-- key指定了在Employee表中插入一个外键来进行关联 -->
			<key column="department_id"/>
			<!-- class属性中指定集合中的类型 -->
			<one-to-many class="Employee"/>
		</set>
	</class>
</hibernate-mapping>