hibernate笔记（四) 一对一 （唯一外键关联）

Room.hbm.xml

<?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.goby.Hibernate.bean">

	<class name="Room" table="t_room">

		<id name="id">
			<generator class="native"></generator>
		</id>

		<property name="address"></property>
		<!--
			constrained(约束) (可选)
			表明该类对应的表对应的数据库表，和被关联的对象所对应的数据库表之间，通过一个外键引用对主键进行约束。
			这个选项影响save()和delete()在级联执行时的先后顺序以及 决定该关联能否被委托(也在schema export
			tool中被使用). 
			
		-->
		<one-to-one name="users" class="User" constrained="true" />
	</class>

</hibernate-mapping>

 

 

User.hbm.xml

<?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.goby.Hibernate.bean">

	<class name="User" table="t_user">

		<id name="id">
			<generator class="native"/>
			
		</id>

		<property name="name"/>
		<!-- 
		cascade(级联) (可选) 表明操作是否从父对象级联到被关联的对象。
		 -->
		<many-to-one name="room" class="Room" column="room_id" cascade="all"/>
	</class>

</hibernate-mapping>

 

Test.java

package test;

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



import junit.framework.TestCase;

import org.hibernate.Session;

import com.goby.Hibernate.bean.HibernateUtils;
import com.goby.Hibernate.bean.Role;
import com.goby.Hibernate.bean.User;

public class test extends TestCase {
	
	public void testSave(){
		Session session = null;
		try{
			
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			Role role1 = new Role();
			role1.setName("manager");
			
			Role role2 = new Role();
			role2.setName("officer");
			
			Role role3 = new Role();
			role3.setName("normal");
			
			Set roles1 = new HashSet();
			roles1.add(role1);
			roles1.add(role2);
			
			Set roles2 = new HashSet();
			roles2.add(role1);
			roles2.add(role3);
			
			User user1 = new User();
			user1.setName("goby");
			user1.setRoles(roles1);
			
			User user2 = new User();
			user2.setName("qq");
			user2.setRoles(roles2);
			
			session.save(user1);
			session.save(user2);
			
			session.getTransaction().commit();
			
		}catch(Exception ex){
			ex.printStackTrace();
			session.getTransaction().rollback();
		}finally{
			HibernateUtils.closeSession(session);
		}
	}
	
	/*
	 * 从User类中获取数据
	 */
	public void testload(){
		Session session = null;
		try{
			
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			User user = (User)session.load(User.class, 3);
			System.out.println("user.name="+user.getName());
			Set roles = user.getRoles();
			for(Iterator iter = roles.iterator();iter.hasNext();){
				Role role = (Role)iter.next();
				System.out.println("role.name="+role.getName());
			}
			
			session.getTransaction().commit();
			
		}catch(Exception ex){
			ex.printStackTrace();
			session.getTransaction().rollback();
		}finally{
			HibernateUtils.closeSession(session);
		}
	}
	
	/*
	 * 从Role类中获取数据
	 */
	public void testload2(){
		Session session = null;
		try{
			
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			Role role = (Role)session.load(Role.class, 1);
			System.out.println("role.name="+role.getName());
			Set users = role.getUsers();
			for(Iterator iter = users.iterator();iter.hasNext();){
				User user = (User)iter.next();
				System.out.println("user.name="+user.getName());
			}
			
			session.getTransaction().commit();
			
		}catch(Exception ex){
			ex.printStackTrace();
			session.getTransaction().rollback();
		}finally{
			HibernateUtils.closeSession(session);
		}
	}
}