微软提供了PagedList分页，相信大家在网上也能搜索一大堆关于pagedList用法的博客，论坛。但是，在使用的过程中一不小心，就会掉入pagedList某种常规用法的陷阱。
我所说的某种常规用法是指如下方法(也可以参考我的博客：PagedList 分页用法)：
代码如下：
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.Mvc;
using System.Linq;
using EF_Test.DAL;
using System.Data;
using PagedList;
namespace EF_Test.Controllers
{
public class HomeController : Controller
{
private StudentContext db = new StudentContext();
/// <summary>
/// 简单分页演示
/// </summary>
/// <param name="page">页码</param>
/// <returns></returns>
public ActionResult Index2(int page = 1)//查询所有学生数据
{
return View(db.Students.OrderBy(item => item.Id).ToPagedList(page, 9));
}
}
}
前端HTML
@model PagedList.IPagedList<EF_Test.DAL.Student>
@using PagedList.Mvc
@{
ViewBag.Title = "Index";
Layout = "~/Views/Shared/_Layout.cshtml";
}
@section css{
<link href="~/Content/PagedList.css" rel="stylesheet" />
<style type="text/css">
body {
font-size: 12px;
font-family: "微软雅黑";
color: #555;
position: relative;
background: #fff;
}
a {
text-decoration: none;
color: #555;
}
#tbList {
border: 1px solid none;
800px;
margin: 10px auto;
border-collapse: collapse;
}
#tbList th, td {
border: 1px solid #ccc;
padding: 5px;
text-align: center;
}
tfoot tr td {
border: none;
}
</style>
}
@using (Html.BeginForm("Index", "Home", FormMethod.Get))
{
<div style="text-align: center;">
<h1>Mvc分页例子</h1>
<table id="tbList">
<tbody>
@if (Model.Count() != 0)
{
<tr>
<th>姓名
</th>
<th>性别
</th>
<th>学号
</th>
</tr>
foreach (var item in Model)
{
<tr style="text-align: center;">
<td>
@Html.DisplayFor(modelItem => item.Name)
</td>
<td>
@Html.DisplayFor(modelItem => item.Sex)
</td>
<td>
@Html.DisplayFor(modelItem => item.StudentNum)
</td>
</tr>
}
}
</tbody>
<tfoot>
<tr>
<td colspan="5">
<div class="">
@if (Model != null)
{
<span style="height: 20px; line-height: 20px;">共 @Model.TotalItemCount.ToString() 条记录，当前第 @Model.PageNumber 页/共 @Model.PageCount 页 </span>
@Html.PagedListPager(Model, page => Url.Action("Index", new { page }), new PagedListRenderOptions() { LinkToFirstPageFormat = "首页", LinkToNextPageFormat = "下一页", LinkToPreviousPageFormat = "上一页", LinkToLastPageFormat = "末页", DisplayItemSliceAndTotal = false, MaximumPageNumbersToDisplay = 3 })
}
</div>
</td>
</tr>
</tfoot>
</table>
</div>
}
上述的用法很简单，直接查询所有数据，然后利用pagedList提供的HTML helper 进行分页。
其效果图也不错，如下：
上述中红色字体提到：该用法需要一次性查询表中所有数据，试问：如果您的数据表中有百万甚至千万条数据，那么这种用法效率是不是将会很低？
说来也惭愧，当初用的时候，我也想到了这个弊端，但是一直没去想办法解决这个问题。
还好，pagedList还提供了另外一种方法：StaticPagedList 方法
StaticPagedList 方法需要提供四个参数，分别为：数据源 当前页码 每页条数 以及总记录数
如上述所言，我们在查询的过程中不能一次性查询所有数据，因为这样做效率很低。而现在我们要做的就是查询当前页码的 10 条数据(假设每页展示十条数据)及返回数据表中的总记录数。
那么我们该怎么做呢？
方法其实很多，在我的项目中，我用到一个存储过程<不管你用什么，你现在要做的就是返回：当前页码的 10 条数据，及数据表总记录条数>
我用到的存储过程为：请参考我的上篇博客
有了存储过程，我们就要用EF执行这个存储过程，怎么执行呢？
接口层：
IEnumerable<StudentModel> GetPagePro(string tableName, string fields, string orderField, string sqlWhere, int pageSize, int pageIndex, out int totalPage, out int RecordCount);
执行层：继承接口
/// <summary>
/// EF执行存储过程
/// </summary>
/// <param name="tableName">表名</param>
/// <param name="fields">所要查询的字段</param>
/// <param name="orderField">排序字段</param>
/// <param name="sqlWhere">条件语句 where</param>
/// <param name="pageSize">页容量</param>
/// <param name="pageIndex">页码</param>
/// <param name="totalPage">out参数 总分页数量</param>
/// <param name="RecordCount">out 参数 总记录数</param>
/// <returns></returns>
public IEnumerable<StudentModel> GetPagePro(string tableName, string fields, string orderField, string sqlWhere, int pageSize, int pageIndex, out int totalPage, out int RecordCount)
{
using (StudentEntities context = new StudentEntities())
{
SqlParameter[] parameters = {
new SqlParameter("@TableName", SqlDbType.NText),
new SqlParameter("@Fields", SqlDbType.NText),
new SqlParameter("@OrderField", SqlDbType.NText),
new SqlParameter("@sqlWhere", SqlDbType.NText),
new SqlParameter("@pageSize", SqlDbType.Int),
new SqlParameter("@pageIndex", SqlDbType.Int),
new SqlParameter("@TotalPage", SqlDbType.Int),
new SqlParameter("@RecordCount", SqlDbType.Int)
};
parameters[0].Value = tableName;
parameters[1].Value = fields;
parameters[2].Value = orderField;
parameters[3].Value = sqlWhere;
parameters[4].Value = pageSize;
parameters[5].Value = pageIndex;
parameters[6].Direction = ParameterDirection.Output;
parameters[7].Direction = ParameterDirection.Output;
var data = context.Database.SqlQuery<StudentModel>("exec [ZXL_GetPageData] @TableName,@Fields,@OrderField,@sqlWhere,@pageSize,@pageIndex,@TotalPage out,@RecordCount out", parameters).ToList();
int count = data.Count;
//
string n6 = parameters[6].Value.ToString();
string n7 = parameters[7].Value.ToString();
//
totalPage = !string.IsNullOrEmpty(n6) ? int.Parse(n6) : 0;
RecordCount = !string.IsNullOrEmpty(n7) ? int.Parse(n7) : 0;
return data;
}
}
实体Model层：
public class StudentModel
{
public int Id { get; set; }
public string StuNum { get; set; }
public string deptNum { get; set; }
public string StuName { get; set; }
public string StuSex { get; set; }
public Nullable<System.DateTime> AddTime { get; set; }
}
控制器代码：
public ActionResult Index(int page=1)//查询所有学生数据
{
int totalPage=0;
int recordCount=0;
var data = studentdb.GetPagePro("Student", "*", "Id", "", 10, page, out totalPage, out recordCount);
var studentList = new StaticPagedList<StudentModel>(data,page,10,recordCount);
return View(studentList);//
}
UI/View层
@model PagedList.StaticPagedList<Test.Model.StudentModel>
@using PagedList.Mvc
@using PagedList
@{
ViewBag.Title = "Index";
Layout = null;
}
<link href="~/Content/PagedList.css" rel="stylesheet" />
<style type="text/css">
body {
font-size: 12px;
font-family: "微软雅黑";
color: #555;
position: relative;
background: #fff;
}
a {
text-decoration: none;
color: #555;
}
#tbList {
border: 1px solid none;
800px;
margin: 10px auto;
border-collapse: collapse;
}
#tbList th, td {
border: 1px solid #ccc;
padding: 5px;
text-align: center;
}
tfoot tr td {
border: none;
}
</style>
@using (Html.BeginForm("Index", "Home", FormMethod.Get))
{
<div style="text-align: center;">
<h1>Mvc分页例子</h1>
<table id="tbList">
@* <thead>
<tr>
<th>
<input id="StuName" name="StuName" type="text" placeholder="请输入姓名" />
</th>
<th>
<input id="StuNum" name="StuNum" type="text" placeholder="请输入学号" />
</th>
<th>
<input id="Submit1" type="submit" value="submit" />
</th>
</tr>
</thead>*@
<tbody>
@if (Model.Count() != 0)
{
<tr>
<th>姓名
</th>
<th>性别
</th>
<th>学号
</th>
</tr>
foreach (var item in Model)
{
<tr style="text-align: center;">
<td>
@Html.DisplayFor(modelItem => item.StuName)
</td>
<td>
@Html.DisplayFor(modelItem => item.StuSex)
</td>
<td>
@Html.DisplayFor(modelItem => item.StuNum)
</td>
</tr>
}
}
</tbody>
<tfoot>
<tr>
<td colspan="5">
<div class="">
@if (Model != null)
{
<span style="height: 20px; line-height: 20px;">共 @Model.TotalItemCount.ToString() 条记录，当前第 @Model.PageNumber 页/共 @Model.PageCount 页 </span>
@Html.PagedListPager(Model, page => Url.Action("Index", new { page }), new PagedListRenderOptions() { LinkToFirstPageFormat = "首页", LinkToNextPageFormat = "下一页", LinkToPreviousPageFormat = "上一页", LinkToLastPageFormat = "末页", DisplayItemSliceAndTotal = false, MaximumPageNumbersToDisplay = 3 })
}
</div>
</td>
</tr>
</tfoot>
</table>
</div>
}
上述代码已经很齐全了，大家可以自行尝试，需要说明两点：
控制器代码：
view层HTML代码：
至此，整个pagedList分页就完毕了。
这样查询提升了效率。
我的分页效果图如下：
由图可知，我的数据表共有：151303条记录，如果采用每次都加载所有数据，效率是何其低可想而知。
呵呵，截止到这儿，pagedlist分页也就讲完了！
现在，我们提出新的要求：结合查询，根据学生姓名和学号进行模糊查询
其后端变更如下：
public ActionResult Index(int page = 1, string StuName = "", string StuNum = "",string sortOrder="")//查询所有学生数据
{
string where = string.Empty;
if (!string.IsNullOrEmpty(StuName))
{
ViewBag.StuName = StuName;
where += " and StuName like '%" + StuName + "%'";
}
if (!string.IsNullOrEmpty(StuNum))
{
ViewBag.StuNum = StuNum;
where += " and StuNum like '%" + StuNum + "%'";
}
int totalPage = 0;
int recordCount = 0;
var data = model.GetPagePro("Student", "*", "Id", " 1=1 " + where, 10, page, out totalPage, out recordCount);
var studentList = new StaticPagedList<StudentModel>(data, page, 10, recordCount);
return View(studentList);//
}
前端如下：
@model PagedList.StaticPagedList<Test.Model.StudentModel>
@using PagedList.Mvc
@using PagedList
@{
ViewBag.Title = "Index";
Layout = null;
}
<link href="~/Content/PagedList.css" rel="stylesheet" />
<style type="text/css">
body {
font-size: 12px;
font-family: "微软雅黑";
color: #555;
position: relative;
background: #fff;
}
a {
text-decoration: none;
color: #555;
}
#tbList {
border: 1px solid none;
800px;
margin: 10px auto;
border-collapse: collapse;
}
#tbList th, td {
border: 1px solid #ccc;
padding: 5px;
text-align: center;
}
tfoot tr td {
border: none;
}
</style>
@using (Html.BeginForm("Index", "Home", FormMethod.Get))
{
<div style="text-align: center;">
<h1>Mvc分页例子</h1>
<table id="tbList">
<thead>
<tr>
<th>
<input id="StuName" name="StuName" type="text" placeholder="请输入姓名" value="@ViewBag.StuName" />
</th>
<th>
<input id="StuNum" name="StuNum" type="text" placeholder="请输入学号" value="@ViewBag.StuNum" />
</th>
<th>
<input id="Submit1" type="submit" value="submit" />
</th>
</tr>
</thead>
<tbody>
@if (Model.Count() != 0)
{
<tr>
<th>姓名
</th>
<th>性别
</th>
<th>学号
</th>
</tr>
foreach (var item in Model)
{
<tr style="text-align: center;">
<td>
@Html.DisplayFor(modelItem => item.StuName)
</td>
<td>
@Html.DisplayFor(modelItem => item.StuSex)
</td>
<td>
@Html.DisplayFor(modelItem => item.StuNum)
</td>
</tr>
}
}
</tbody>
<tfoot>
<tr>
<td colspan="5">
<div class="">
@if (Model != null)
{
<span style="height: 20px; line-height: 20px;">共 @Model.TotalItemCount.ToString() 条记录，当前第 @Model.PageNumber 页/共 @Model.PageCount 页 </span>
@Html.PagedListPager(Model, page => Url.Action("Index", new { page,StuName=ViewBag.StuName,StuNum=ViewBag.StuNum }), new PagedListRenderOptions() { LinkToFirstPageFormat = "首页", LinkToNextPageFormat = "下一页", LinkToPreviousPageFormat = "上一页", LinkToLastPageFormat = "末页", DisplayItemSliceAndTotal = false, MaximumPageNumbersToDisplay = 3 })
}
</div>
</td>
</tr>
</tfoot>
</table>
</div>
}
上图为变更处、
运行效果：
