many2onetest.java

hibernate 关联实例包括（一对一关联）一对多关联(单向

package com.bjsxt.hibernate;

import org.hibernate.Session;

import junit.framework.TestCase;

public class Many2OneTest extends TestCase {
	
	public void testSaveMany2one1() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			Group group = new Group();
			group.setName("java开发组");
			
			for (int i = 0; i < 10 ; i++) {
				User user = new User();
				user.setName("User_" + i);
				
				//建立对象之间的关系
				user.setGroup(group);
				
				//因为user引用了Transient对象（group），所以抛出了TransientObjectException
			    //持久对象不能直接引用瞬时对象	
				session.save(user);
				
			}
			
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}
	
	public void testSaveMany2one2() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			Group group = new Group();
			group.setName("java开发组");
			
			//将group转换为持久对对象 
			session.save(group);
			
			for (int i = 0; i < 10 ; i++) {
				User user = new User();
				user.setName("User_" + i);
				
				//建立对象之间的关系
				user.setGroup(group);
				
				//因为group为持久对象，所以可以成功保存
				session.save(user);
			}
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}
	
	public void testSaveMany2one3() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			Group group = new Group();
			group.setName("java开发组");
			
			for (int i = 0; i < 10 ; i++) {
				User user = new User();
				user.setName("User_" + i);
				
				//建立对象之间的关系
				user.setGroup(group);
				
				//通过级联，是解决TransientObjectException异常的一种手段
				session.save(user);
			}
			
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}
	
	/**
	 * 转载User对象
	 *
	 */
	public void testLoadUser() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			User user = (User)session.load(User.class, 20);
			System.out.println("user name=" + user.getName());
			System.out.println("related group=" + user.getGroup().getName());
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			
		}
	}
	
}