在 asp.net mvc中的简单分页算法

//第一步：建立如下分页实体类:
namespace MVCPager.Helpers
{
    /// <summary>
    /// 简单分页算法类
    /// </summary>
    public class Pager
    {
        public int RecordCount { get; set; }

        public int PageIndex { get; set; }

        public int PageSize { get; set; }

        public int PageCount
        {
            get
            {
                return (RecordCount - 1) / PageSize + 1;
            }
        }

        const int SHOW_COUNT = 6; //这个常量表示两边都有省略号时，中间的分页链接的个数,如 1..4 5 6 7 8 9 .. 100
        private List<int> CalcPages()
        {
            List<int> pages = new List<int>();

            int start = (PageIndex - 1) / SHOW_COUNT * SHOW_COUNT + 1;
            int end = Math.Min(PageCount, start + SHOW_COUNT - 1);

            if (start == 1)
            {
                end = Math.Min(PageCount, end + 1);
            }
            else if (end == PageCount)
            {
                start = Math.Max(1, end - SHOW_COUNT);
            }
            pages.AddRange(Enumerable.Range(start, end - start + 1));

            if (start == PageIndex && start > 2)
            {
                pages.Insert(0, start - 1);
                pages.RemoveAt(pages.Count - 1);//保持显示页号个数统一
            }
            if (end == PageIndex && end + 1 < PageCount)
            {
                pages.Add(end + 1);
                pages.RemoveAt(0);  //保持显示页号个数统一
            }
            if (PageCount > 1)
            {
                if (pages[0] > 1)
                {
                    pages.Insert(0, 1); //如果页列表第一项不是第一页，则在队头添加第一页
                }
                if (pages[1] == 3)
                {
                    pages.Insert(1, 2); //如果是1..3这种情况，则把..换成2
                }
                else if (pages[1] > 3)
                {
                    pages.Insert(1, -1); //插入左侧省略号
                }

                if (pages.Last() == PageCount - 2)
                {
                    pages.Add(PageCount - 1); //如果是 98..100这种情况，则..换成99
                }
                else if (pages.Last() < PageCount - 2)
                {
                    pages.Add(-1); //插入右侧省略号
                }

                if (pages.Last() < PageCount)
                {
                    pages.Add(PageCount); //最后一页
                }
            }

            return pages;
        }

        /// <summary>
        /// 用于显示的页号数组，如果中间有小于0的页号，则表示是省略号
        /// </summary>
        public List<int> Pages
        {
            get
            {
                return CalcPages();
            }
        }
    }
}

@using MVCPager.Helpers;
@{
    Layout = null;
    var _id = ViewContext.RouteData.Values["id"];
    var _action = ViewContext.RouteData.Values["action"].ToString();

    Pager _pager = ViewBag.Pager as Pager;
}

<div style="text-align:right">
    <ul class="pagination">
        @if (_pager.PageIndex == 1)
        {

            <li><a href="###">&laquo;</a></li>
        }
        else
        {
            <li>
                @Html.ActionLink("?", _action, new { id = _id, page = _pager.PageIndex - 1 })
            </li>
        }
        @foreach (int p in _pager.Pages)
        {
            if (p < 0)
            {
                <li><a>- - -</a></li>
            }
            else if (p == _pager.PageIndex)
            {
                <li class="active">
                    <a href="#">@p</a>
                </li>
            }
            else
            {
                <li>@Html.ActionLink(p.ToString(), _action, new { id = _id, page = p })</li>
            }
        }
        @if (_pager.PageIndex == _pager.PageCount)
        {
            <li><a href="###">&raquo;</a></li>
        }
        else
        {
            <li>
                @Html.ActionLink("?", _action, new { id = _id, page = _pager.PageIndex + 1 })
            </li>
        }
    </ul>
</div>

<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.Title)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Editor.UserName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.EditTime)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Catalog.Name)
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.Title)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Editor.UserName)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.EditTime)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Catalog.Name)
        </td>
        <td>
            @Html.ActionLink("编辑", "Edit", new { id=item.Id }) |
            @Html.ActionLink("查看", "Details", new { id=item.Id }) |
            @Html.ActionLink("删除", "Delete", new { id=item.Id })
        </td>
    </tr>
}

</table>
@Html.Partial("Pager")