用hibernate实现数据库底层分页 (转自ejunnet)

2023-10-11 21:45

1、创建SessionFactory,为了减轻服务器负担,保证一个应用中仅生成一个SessionFactory即可.

package dao;

import org.hibernate.cfg. * ;

import org.hibernate. * ;

public class MySessionFactory ... {

private static Configuration config=null;

private static SessionFactory sf=null;

private MySessionFactory()...{

config=new Configuration().configure();

sf=config.buildSessionFactory();

}

public static SessionFactory getSessionFactory()...{

if(sf==null)...{

new MySessionFactory();

}

return sf;

}

}

2、实现分页过程
方法getTotalPage()得到总页数, getObject()将所查询的数据封装到list里！

package dao;

import java.util.List;

import org.hibernate.Query;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

public class pageList ... {

// 分页实现代码:

// 得到总页数 pagesize为一个页面显示的记录数

public int getTotalPage(String hql, int pagesize) ...{

SessionFactory sf = MySessionFactory.getSessionFactory();

Session session = sf.openSession();

Transaction ts = session.beginTransaction();

Query query = session.createQuery(hql);

List list = query.list();

int totalrs = list.size();

int totalpage = 0;

if (totalrs % pagesize > 0) ...{

totalpage = totalrs / pagesize + 1;

} else ...{

totalpage = totalrs / pagesize;

}

ts.commit();

session.close();

return totalpage;

}

// 分页list

public List getObject(String hql, int page, int pagesize) ...{

if (page < 1)page = 1;

SessionFactory sf = MySessionFactory.getSessionFactory();

Session session = sf.openSession();

Transaction ts = session.beginTransaction();

Query query = session.createQuery(hql);

query.setFirstResult(page * pagesize - pagesize);

query.setMaxResults(pagesize);

List list = query.list();

ts.commit();

// session.close();

return list;

}

// 分页代码完

}

代码中page为请求的页面，pagesize为一个页面显示的记录数。

3、应用实例：

<% ... @ page language="java" contentType="text/html; charset=GBK"

pageEncoding="GBK" %>

<% ... @ page import="dao.*,po.*,java.util.*" %>

<% ... @ taglib uri="http://www.gavelz.com/struts/tags-bean"

prefix="bean" %>

<% ... @ taglib uri="http://www.gavelz.com/struts/tags-html"

prefix="html" %>

<% ...

String nowpage = request.getParameter("page");

//如果请求业面为空或第一次访问时，页面设为1

if (nowpage == null || nowpage.equals(""))nowpage = "1";

//将nowpage转为整型

int mypage = Integer.parseInt(nowpage);

if (mypage <= 0)mypage = 1;

//页面记录数设为10

int pagesize = 10;

String hql = "from ExamStudent";

pageList pl = new pageList();

int totalpage = pl.getTotalPage(hql, pagesize);

//当请求页面大于总页数，则将当前请求页面设为最大页数

if (mypage > totalpage)mypage = totalpage;

ArrayList list = (ArrayList) pl.getObject(hql, mypage,pagesize);

Iterator it = list.iterator();

%>

< html >

< head >

< title > JSP for AddStudentForm form title >

head >

< body >

< table border ="1" >

< tr >

< td > 学号 td >

< td > 姓名 td >

< td > 性别 td >

< td > 电话 td >

< td colspan ="2" > 操作 td >

tr >

<% ...

while (it.hasNext()) {

ExamStudent es = (ExamStudent) www.gavelz.com();

%>

< tr >

< td > <% = es.getStudentClassid() %> td >

< td > <% = es.getStudentName() %> td >

< td > <% = es.getStudentSex() %> td >

< td > <% = es.getStudentTel() %> td >

< td >< a href ="updateStudent.jsp?id=<%=es.getStudentId()%>" > 修改 a > td >

< td >< a href ="/exam/deleteStudent?id=<%=es.getStudentId()%>" > 删除 a > td >

tr >

<% ...

}

list.clear();

%>

< tr >

< td colspan ="6" >< a href ="addStudent.jsp?page=1" > 首页 a > || < a

href ="addStudent.jsp?page=<%=mypage-1%>" > 上一页 a > || < a

href ="addStudent.jsp?page=<%=mypage+1%>" > 下一页 a > || < a

href ="addStudent.jsp?page=<%=totalpage%>" > 末页 a > td >

tr >

table >

body >

html >

页面中page ,nowpage,mypage均为当前请求页面，只是数据类型不同。

//完第一次用hibernate做分页，如有错误或不好的地方请多多指教！！