hibernate学习7之many-to-many双向关联

Hibernate.cfg.xml配置同前一节。

import java.util.Set;
public class User {
	private int id;
	private String name;
	private Set roles; 
	//setter，getter
}

import java.util.Set;
public class Role {	
	private int id;	
	private String name;	
	private Set users;
	//setter，getter
}

User.hbm.xml中这样配置：

<?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>
	<class name="com.bjsxt.hibernate.User" table="t_user">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
		<set name="roles" table="t_user_role">
			<key column="userid"/>
			<many-to-many class="com.bjsxt.hibernate.Role" column="roleid"/>
		</set>
	</class>
</hibernate-mapping>

Role.hbm.xml中这样配置：

<?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>
	<class name="com.bjsxt.hibernate.Role" table="t_role">
		<id name="id">
			<generator class="native"/>
		</id>
		<property name="name"/>
		<set name="users" table="t_user_role" order-by="userid">
			<key column="roleid"/>
			<many-to-many class="com.bjsxt.hibernate.User" column="userid"/>
		</set>
	</class>
</hibernate-mapping>

比较上面2个配置，其实userid和roleid互换位置而已；
这里order-by="userid"是查出来的数据根据userid排序，去掉也没关系。
测试一下：

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

import org.hibernate.Session;

import junit.framework.TestCase;

public class Many2Many extends TestCase {

	public void testSave2() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			Role r1 = new Role();
			r1.setName("数据录入人员");
			session.save(r1);
			
			Role r2 = new Role();
			r2.setName("商务主管");
			session.save(r2);
			
			Role r3 = new Role();
			r3.setName("大区经理");
			session.save(r3);
			
			User u1 = new User();
			u1.setName("10");
			Set u1Roles = new HashSet();
			u1Roles.add(r1);
			u1Roles.add(r2);
			u1.setRoles(u1Roles);
			
			User u2 = new User();
			u2.setName("祖儿");
			Set u2Roles = new HashSet();
			u2Roles.add(r2);
			u2Roles.add(r3);
			u2.setRoles(u2Roles);
			
			User u3 = new User();
			u3.setName("杰伦");
			Set u3Roles = new HashSet();
			u3Roles.add(r1);
			u3Roles.add(r2);
			u3Roles.add(r3);
			u3.setRoles(u3Roles);
			
			session.save(u1);
			session.save(u2);
			session.save(u3);
			
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}		
	
	public void testLoad1() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			User user = (User)session.load(User.class, 1);
			System.out.println(user.getName());
			for (Iterator iter=user.getRoles().iterator(); iter.hasNext();) {
				Role role = (Role)iter.next();
				System.out.println(role.getName());
			}
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}		
	
	public void testLoad2() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			Role role = (Role)session.load(Role.class, 1);
			System.out.println(role.getName());
			for (Iterator iter=role.getUsers().iterator(); iter.hasNext();) {
				User user = (User)iter.next();
				System.out.println(user.getName());
			}
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}		
	
}