one2manytest.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 java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.hibernate.Session;

import junit.framework.TestCase;

public class One2ManyTest extends TestCase {
	
	public void testSaveOne2Many1() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			Set students = new HashSet();
			for (int i = 0; i < 10; i++) {
				Student student = new Student();
				student.setName("student_" + i);
				students.add(student);
			}
			
			Classes classes = new Classes();
			classes.setName("class_1");
			
			//建立对象引用关系
			classes.setStudents(students);
				
			//不能成功保存，因为Student是瞬时对象
			session.save(classes);
			session.getTransaction().commit();
			
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}
	
	public void testSaveOne2Many2() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			session.beginTransaction();
			
			Set students = new HashSet();
			for (int i = 0; i < 10; i++) {
				Student student = new Student();
				student.setName("student_" + i);
				
				//将student持久化
				session.save(student);
				students.add(student);
			}
			
			Classes classes = new Classes();
			classes.setName("class_1");
			
			//建立对象引用关系
			classes.setStudents(students);
				
			//不会抛出异常，因为Student是持久对象
			session.save(classes);
			session.getTransaction().commit();
		}catch(Exception e) {
			e.printStackTrace();
			session.getTransaction().rollback();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}
	
	public void testLoadOne2Many() {
		Session session = null;
		try {
			session = HibernateUtils.getSession();
			Classes classes = (Classes)session.load(Classes.class, 1);
			System.out.println("班级名称：" + classes.getName() + "拥有学生：");
			Set students = classes.getStudents();
			for (Iterator iter=students.iterator();iter.hasNext();) {
				Student student = (Student)iter.next();
				System.out.println(student.getName());
			}
		}catch(Exception e) {
			e.printStackTrace();
		}finally {
			HibernateUtils.closeSession(session);
		}
	}	
}