10.Hibernate的多对多双向关联映射

hibernate多对多关联映射(双向User<---->Role)

映射方法：
        <set name="roles" table="t_user_role">
            <key column="userid"/>
            <many-to-many class="com.bjsxt.hibernate.Role" column="roleid"/>
        </set>
table属性值必须和单向关联中的table属性值一致
<key>中column属性值要与单向关联中的<many-to-many>标签中的column属性值一致
在<many-to-many>中的column属性值要与单向关联中<key>标签的column属性值一致

 

一：实体类：

package com.tao.hibernate.many2many2;

import java.util.Set;

public class Role {
	private Integer id;
	private String name;
	private Set<User> users;

	public Role() {
		super();
	}

	public Integer getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

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

	public Set<User> getUsers() {
		return users;
	}

	public void setUsers(Set<User> users) {
		this.users = users;
	}

}

 

package com.tao.hibernate.many2many2;

import java.util.Set;

public class User {
	private Integer id;
	private String name;
	private Set<Role> roles;

	public User() {
		super();
	}

	public Integer getId() {
		return id;
	}

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

	public String getName() {
		return name;
	}

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

	public Set<Role> getRoles() {
		return roles;
	}

	public void setRoles(Set<Role> roles) {
		this.roles = roles;
	}
}

 

二：映射文件：

<?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.tao.hibernate.many2many2"
	auto-import="false">
	<class name="Role" table="t_role">
		<id name="id" column="id" type="integer">
			<generator class="native">
			</generator>
		</id>
		<property name="name" column="name" />
		<set name="users" table="t_user_role" order-by="userId">
			<key column="roleId" />
			<many-to-many class="User" column="userId" />
		</set>
	</class>
</hibernate-mapping>

 

<?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.tao.hibernate.many2many2"
	auto-import="false">
	<class name="User" table="t_user">
		<id name="id" column="id" type="integer">
			<generator class="native">
			</generator>
		</id>
		<property name="name" column="name" />
		<set name="roles" table="t_user_role" cascade="all">
			<key column="userId" />
			<many-to-many class="Role" column="roleId" />
		</set>
	</class>
</hibernate-mapping>

 

三：测试类：

package com.tao.hibernate.many2many2;

import java.util.Iterator;

import org.hibernate.Session;
import org.junit.Test;

import com.tao.hibernate.HibernateUtils;

public class TestMain {
	Session session = HibernateUtils.getFactory().openSession();

	@Test
	public void testLoad() {
		Session session = HibernateUtils.getFactory().openSession();
		Role r1 = (Role) session.load(Role.class, 1);
		System.out.println(r1.getName());
		for (Iterator<User> iter = r1.getUsers().iterator(); iter.hasNext();) {
			System.out.println(iter.next().getName());
		}
	}

}