实现Javawb分页技术

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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);
}
}