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实现Javawb分页技术

2011-11-15 21:15 288 查看

分页技术解析：

第一步：查询出总记录数

select count(*) as c from news; countrecord(总记录数)

第二步：定义出每页的记录数

pagesize=10;

第三步：计算总页数

当前页：nowpage=1;

查询出第一页的记录；

select * from news limit 1,10;//第一页

select * from news limit 10,10；//第二页

//当前页应该从第几条记录开始

(当前页-1)*10

第n页应该是：(nowpage-1)*pagesize

select * from new slimit (nowpage-1)*pagesize,pagesize;

代码实现：

1、首先创建一个 index.jsp页面，实现页面。

代码：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<base href="<%=basePath%>">

<title>My JSP 'index.jsp' starting page</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">



</head>

<body>

<div align="center">

<div>

<table border="1px" cellpadding="0" cellspacing="0">

<thead>

<tr>

<th>序号</th>

<th>标题</th>

<th>内容</th>

<th>操作</th>

</tr>

</thead>

<tbody>

<c:forEach items ="${entities}" var="entity">

<tr>

<td>${entity.id}</td>

<td>${entity.title}</td>

<td>${entity.content}</td>

<td>

<a href="#">修改</a>

<a href="#">删除</a>

</td>

</tr>

</c:forEach>

</tbody>

</table>

</div>

<br/>

<div>

<span><a href="${pageContext.request.contextPath }/news.do">首页</a></span>

<span><a href="${pageContext.request.contextPath }/news.do?nowpage=${countPage-1}">上一页</a></span>

<span><a href="${pageContext.request.contextPath }/news.do?nowpage=${countPage+1}">下一页</a></span>

<span><a href="${pageContext.request.contextPath }/news.do?nowpage=${countPage}">末页</a></span>

<span>总记录数：${countRecord},总页数：${countPage},当前页：${nowpage}</span>

</div>

</div>

</body>

</html>

2、创建一个 servlet实现页面程序：

package cn.csdn.web.servlet;

import java.io.IOException;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import cn.csdn.web.domin.News;

import cn.csdn.web.service.NewsService;

import cn.csdn.web.service.NewsServiceImpl;

public class NewsListServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// 获取当前页

NewsService nService = new NewsServiceImpl();

// 记录数

Integer countRecord = nService.findCountRecord();

// 页数

Integer countPage = nService.findCountPage();

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

int nowpage = 1;

if ("".equals(npage) || npage == null) {

nowpage = 1;

} else {

nowpage = Integer.parseInt(npage);

}

if(nowpage<=1){

nowpage=1;

}

if(nowpage >= countPage){

nowpage = countPage;

}

// 当前页面

List<News> entities = nService.findNowPageInfo(nowpage);

// 转发

request.setAttribute("entities", entities);

request.setAttribute("countRecord", countRecord);

request.setAttribute("countPage", countPage);

request.setAttribute("nowpage", nowpage);

request.getRequestDispatcher("./index.jsp").forward(request, response);

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

this.doGet(request, response);

}

}

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