initdata.java

实现一些hibernate底层的东西

package com.bjsxt.hibernate;

import java.text.SimpleDateFormat;
import java.util.Date;

import org.hibernate.Session;

public class InitData {

	public static void main(String[] args) {
			Session session = HibernateUtils.getSession();

			try {
				session.beginTransaction();

				for(int i=0; i<10; i++){
				
					Classes classes = new Classes();
					classes.setName("班级"+i);
					session.save(classes);
					
					for(int j=0; j<10; j++){
						Student student = new Student();
						student.setName("班级"+i+"的学生"+j);
						student.setCreateTime(randomDate("2008-01-01","2008-03-01"));
						
						//在内存中建立由student指向classes的引用
						student.setClasses(classes);
						session.save(student);
					}
				}
				
				for(int i=0; i<5; i++){
					Classes classes = new Classes();
					classes.setName("无学生班级"+i);
					session.save(classes);
				}
				
				for(int i=0; i<10; i++){
					Student student = new Student();
					student.setName("无业游民"+i);
					session.save(student);
				}
				
				session.getTransaction().commit();
			} catch (Exception e) {
				e.printStackTrace();
				session.getTransaction().rollback();
			} finally{
				HibernateUtils.closeSession(session);
			}
		}	
		
		/**
		 * 获取随机日期
		 * @param beginDate 起始日期，格式为：yyyy-MM-dd
		 * @param endDate 结束日期，格式为：yyyy-MM-dd
		 * @return
		 */
		private static Date randomDate(String beginDate,String endDate){
			try {
				SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
				Date start = format.parse(beginDate);
				Date end = format.parse(endDate);
				
				if(start.getTime() >= end.getTime()){
					return null;
				}
				
				long date = random(start.getTime(),end.getTime());
				
				return new Date(date);
			} catch (Exception e) {
				e.printStackTrace();
			}
			return null;
		}
		
		private static long random(long begin,long end){
			long rtn = begin + (long)(Math.random() * (end - begin));
			if(rtn == begin || rtn == end){
				return random(begin,end);
			}
			return rtn;
		}
}