大数据显示时分页

以下封装了，只要传递给servlet一个字段第几页，就可以实现10页为单位的分页效果了。

MySQL:select * from customer limit m,n;
m:每页开始的记录的索引号。（从0开始）
n:每页显示的条数

每页显示10条
第1页的数据：select * from customer limit 0,10;
第2页的数据：select * from customer limit 10,10;
第3页的数据：select * from customer limit 20,10;

每页开始记录的索引=(当前页码-1)*每页显示的条数

总共多少页=总条数%每页显示的条数==0？总条数/每页显示的条数:总条数/每页显示的条数+1；

domain的改造

增加分页类

  1 package cn.itcast.domain;
  2 
  3 import java.util.List;
  4 
  5 //界面上所有与分页有关的都找此类要
  6 public class Page {
  7     private List records;
  8     private int pagesize = 10;//每页显示的记录条数
  9     private int pagenum;//用户要看的页码即当前页码
 10     private int totalpage;//总页数
 11     private int startIndex;//每页开始记录的索引
 12     private int totalrecords;//总记录条数
 13     
 14     //显示的页码
 15     private int startPage;
 16     private int endPage;
 17     
 18     //查询数据时的Servlet的URL
 19     private String servletUrl;
 20     
 21     public Page(int pagenum,int totalrecords){
 22         this.pagenum = pagenum;
 23         this.totalrecords = totalrecords;
 24         
 25         //计算每页开始记录的索引
 26         startIndex = (pagenum-1)*pagesize;
 27         //计算总页数
 28         totalpage = totalrecords%pagesize==0?totalrecords/pagesize:(totalrecords/pagesize+1);
 29         
 30         //显示的页码
 31         if(totalpage<=9){
 32             startPage = 1;
 33             endPage = totalpage;
 34         }else{
 35             startPage = pagenum-4;
 36             endPage = pagenum+4;
 37             if(startPage<1){
 38                 startPage = 1;
 39                 endPage = 9;
 40             }
 41             if(endPage>totalpage){
 42                 endPage = totalpage;
 43                 startPage = totalpage-8;
 44             }
 45         }
 46     }
 47     
 48     
 49     public List getRecords() {
 50         return records;
 51     }
 52     public void setRecords(List records) {
 53         this.records = records;
 54     }
 55     public int getPagesize() {
 56         return pagesize;
 57     }
 58     public void setPagesize(int pagesize) {
 59         this.pagesize = pagesize;
 60     }
 61     public int getPagenum() {
 62         return pagenum;
 63     }
 64     public void setPagenum(int pagenum) {
 65         this.pagenum = pagenum;
 66     }
 67     public int getTotalpage() {
 68         return totalpage;
 69     }
 70     public void setTotalpage(int totalpage) {
 71         this.totalpage = totalpage;
 72     }
 73     public int getStartIndex() {
 74         return startIndex;
 75     }
 76     public void setStartIndex(int startIndex) {
 77         this.startIndex = startIndex;
 78     }
 79     public int getTotalrecords() {
 80         return totalrecords;
 81     }
 82     public void setTotalrecords(int totalrecords) {
 83         this.totalrecords = totalrecords;
 84     }
 85 
 86 
 87     public int getStartPage() {
 88         return startPage;
 89     }
 90 
 91 
 92     public void setStartPage(int startPage) {
 93         this.startPage = startPage;
 94     }
 95 
 96 
 97     public int getEndPage() {
 98         return endPage;
 99     }
100 
101 
102     public void setEndPage(int endPage) {
103         this.endPage = endPage;
104     }
105 
106 
107     public String getServletUrl() {
108         return servletUrl;
109     }
110 
111 
112     public void setServletUrl(String servletUrl) {
113         this.servletUrl = servletUrl;
114     }
115     
116 }

View Code

封装分页的 page.jsp页面

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
 2 <!-- 分页的东东 -->
 3                   第${page.pagenum}页/共${page.totalpage}页&nbsp;&nbsp;
 4                   <a href="${pageContext.request.contextPath}${page.servletUrl}">首页</a>&nbsp;&nbsp;
 5                   <a href="${pageContext.request.contextPath}${page.servletUrl}?pagenum=${page.pagenum-1==0?1:page.pagenum-1}">上一页</a>&nbsp;&nbsp;
 6                   <c:forEach begin="${page.startPage}" end="${page.endPage}" var="num">
 7                       <a href="${pageContext.request.contextPath}${page.servletUrl}?pagenum=${num}">${num }</a>
 8                   </c:forEach>
 9                   &nbsp;&nbsp;
10                   <a href="${pageContext.request.contextPath}${page.servletUrl}?pagenum=${page.pagenum+1>page.totalpage?page.totalpage:page.pagenum+1}">下一页</a>&nbsp;&nbsp;
11                   <a href="${pageContext.request.contextPath}${page.servletUrl}?pagenum=${page.totalpage}">尾页</a>
12                   <select id="s1">
13                       <c:forEach begin="1" end="${page.totalpage}" var="num">
14                           <option value="${num}" ${page.pagenum==num?'selected="selected"':''}>${num}</option>
15                       </c:forEach>
16                   </select>
17                   <a href="javascript:jump()">跳转</a>
18                   <script type="text/javascript">
19                       function jump(){
20                         var num = document.getElementById("s1").value;
21                         window.location.href="${pageContext.request.contextPath}${page.servletUrl}?pagenum="+num;
22                       }
23                   </script>

View Code

显示页面中增加

<%@include file="/WEB-INF/commons/page.jsp" %>

并在foreach标签中指定 requestScope.page.records字段

参考

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
 4 <%@taglib uri="http://www.WFReduceContent.com" prefix="reduce"%>
 5 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 6 <html>
 7 <head>
 8 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 9 <title>Insert title here</title>
10 </head>
11 <body>
12     <form action="${pageContext.request.contextPath }/DelCustomerServlet?method=delMultiple" id="form" method="post">
13     <table >
14         <tr>
15             <th><a href="${pageContext.request.contextPath}/HandleDispatchServlet?method=toAddCustomer">添加</a></th>
16             <th><a href="javascript:delMultiple()">删除</a></th>
17         </tr>
18     </table>
19     <table align ="center" cellpadding="5" border="4" >
20     <tr>
21         <th>选择</th>
22         <th>姓名</th>
23         <th>性别</th>
24         <th>生日</th>
25         <th>电话</th>
26         <th>email</th>
27         <th>爱好</th>
28         <th>类型</th>
29         <th>描述</th>
30         <th>操作</th>
31     </tr>
32         <c:forEach var="customer" items="${requestScope.page.records }" varStatus="status">
33         <tr bgcolor="${status.index%2==0?'red':'gray' }">
34                 <td><input type="checkbox" name="ids" value="${customer.id}"/></td>
35                 <td>${customer.name}</td>
36                 <td>${customer.gender=="1"?"男":"女"}</td>
37                 <td>${customer.birthday}</td>
38                 <td>${customer.cellphone}</td>
39                 <td>${customer.email}</td>
40                 <td>${customer.hobby}</td>
41                 <td>${customer.type}</td>
42                 <td><reduce:reduceContent value="${customer.description}"/> </td>
43                 <td><a href="${pageContext.request.contextPath}/HandleDispatchServlet?method=editCustomer&customerId=${customer.id}">编辑</a>
44                 <a href="javascript:delOne('${customer.id}')">删除</a></td>
45         </tr>
46         </c:forEach>
47     </table>
48     <script type="text/javascript">
49     function delOne(customerId)
50     {
51         var sure=window.confirm("确定删除么?");
52         if(sure)
53         {
54             window.location.href="${pageContext.request.contextPath}/DelCustomerServlet?customerId="+customerId;
55         }
56     }
57     function delMultiple()
58     {
59         var ids=document.getElementsByName("ids");
60         var selected=false;
61         for(var i=0;i<ids.length;i++)
62         {
63             if(ids[i].checked)
64             {
65                 selected=true;
66                 break;
67             }
68         }
69         if(selected)
70         {
71             var sure=window.confirm("确定删除所选记录么?");
72             if(sure)
73             {
74                 document.getElementById("form").submit();
75             }
76         }
77         else
78             {
79                 alert("请先选择要删除的记录");
80             }
81         
82     }
83     </script>
84     </form>
85     <%@include file="/WEB-INF/commons/page.jsp" %>
86 </body>
87 
88 </html>

View Code

DAO层改造：
/**
* 查询记录的总条数
*/
int getTotalRecords();
/**
* 查询分页数据
* @param startIndex 每页开始记录的索引编号
* @param pagesize 每页显示的记录条数
* @return
*/
List<Customer> findPageRecords(int startIndex,int pagesize);

DAO.Impl改造，增加

 1     @Override
 2     public int getTotalRecords() {
 3         int records=0;
 4         try {
 5             QueryRunner runner=new QueryRunner(JdbcUtil.getDataSource());
 6             String sql="select count(*) from customer";
 7              records=(int) (long)runner.query(sql,new ScalarHandler());
 8         } catch (SQLException e) {
 9             e.printStackTrace();
10         }
11         return records;
12         
13     }
14 
15     @Override
16     public List<Customer> findPageRecords(int startIndex, int pagesize) {
17         List<Customer> list=null;
18         try {
19             QueryRunner runner=new QueryRunner(JdbcUtil.getDataSource());
20             String sql="select * from customer limit ? ,?";
21             Object params[]={startIndex,pagesize};
22             list=runner.query(sql,new BeanListHandler<Customer>(Customer.class),params);
23         } catch (SQLException e) {
24             e.printStackTrace();
25         }
26         return list;
27     }

Service改造：
/**
* 根据用户要看的页码返回封装了分页有关数据的Page对象
*/
Page findPageReocrds(String pagenum);

Service.Impl改造增加

 1     @Override
 2     public Page findPageRecords(String pagenum) {
 3         int num = 1;//默认值
 4         if(pagenum!=null&&!"".equals(pagenum.trim()))//如果用户传进来的是null或者是空字符串，则说明第一次访问，默认显示的页码是第1页
 5             num = Integer.parseInt(pagenum);
 6         int totalrecords = dao.getTotalRecords();
 7         Page page = new Page(num, totalrecords);//构造Page对象，因为需要当前页码和总记录条数，所以先通过DAO查出总记录条数
 8                                                 //Page对象一旦构建出来，那么每页开始记录的索引、总页数等都计算出来了
 9                                                 //但是Page对象中的分页记录还木有，所以又通过Dao查询的分页记录
10                                                 //DAO查询分页记录需要每页开始记录的索引和每页显示的条数，这两个参数Page对象中已经计算完毕了
11         List records = dao.findPageRecords(page.getStartIndex(), page.getPagesize());//查询出记录，并设置到Page对象中。这样，任何与分页有关的信息都在Page对象中了
12         page.setRecords(records);
13         return page;
14         //return dao.findPageRecords(startIndex, pagesize);
15     }

Servlet改造：在page.jsp中传递了 pagenum参数，进行查找数据库返回一定的数据。

1 String pagenum = request.getParameter("pagenum");//用户要看的页码
2 Page page = s.findPageReocrds(pagenum);　　　　　　
3 page.setServletUrl("/servlet/ShowAllCustomersServlet");　　//显示数据的Servlet，和servlet相关的地址映射
4 request.setAttribute("page", page);　　　　　　　　　　　　　//存放的对象
5 request.getRequestDispatcher("/listCustomers.jsp").forward(request, response);

posted on 2014-05-22 13:05 wf110 阅读(711) 评论(0) 编辑收藏举报