【ASP.NET MVC 回顾】HtmlHepler应用-分页组件

以前在ASP.NET WebForm开发中会用到许多控件，像DropDownList等。同样ASP.NET MVC中也有类似的控件-HtmlHelper。

HtmlHelper和服务器控件相比，HtmlHelper更灵活一些，而且扩展起来也更方便。实际开发中“分页”功能是必不可少的，于是我自定义了一个HtmlHelper的分页控件，总结出来，希望能帮助到大家。

HtmlHelper扩展方式有两种：

1.@helper

这种方式是使用Razor语法扩展。直接在cshtml中编写即可，非常直观。它有两种实现形式：

• 直接在当前cshtml中编写，然后直接调用：

<h2>Demo</h2>
@helper MyButton(string name,string style){
	//todo: 实现

}
<div>
@MyButton("呵呵","margin:3px 3px;")

</div>

• 在单独的cshtml中编写，在其他文件中调用，这个cshtml文件必须放在App_Code里面：

<h2>Demo1</h2>
<div>
@hHelpers.MyButton("哈哈","Color:red;")
</div>

2.扩展方法利用C#特性-扩展方法来实现扩展，本文将采用这种方式。废话不多说直接上代码。首先先定义一个PageViewData类，用于存储分页的相关信息

public class PageViewData<T>
    {
        /// <summary>
        /// 当前页
        /// </summary>
        public int CurrentPage { get; set; }

        private readonly int _totalPageount;
        /// <summary>
        /// 总页数
        /// </summary>
        public int TotalPageCount
        {
            get
            {
                return _totalPageount;
            }
        }

        private int _totalDataCount;
        /// <summary>
        /// 数据源总量
        /// </summary>
        public int TotalDataCount
        {
            get { return _totalDataCount; }
            set { _totalDataCount = value; }
        }

        private int _pageSize;
        /// <summary>
        /// 每页显示数据大小
        /// </summary>
        public int PageSize
        {
            get { return _pageSize; }
            set { _pageSize = value; }
        }

        /// <summary>
        /// 当前页数据列表
        /// </summary>
        public IList<T> Items { get; set; }

        public PageViewData()
        {
        }

        public PageViewData(int currentPage, int pageSize, int totalDataCount)
        {
            CurrentPage = currentPage;
            _pageSize = pageSize;
            _totalDataCount = totalDataCount;
            _totalPageount = (int)Math.Ceiling(_totalDataCount * 1.0 / _pageSize);
        }

    }

然后开始编写分页组件代码。

public static MvcHtmlString PagePanel<T>(this HtmlHelper html, PageViewData<T> pageViewData,
            Func<int, string> action,
            int showMaxPageCount = 10,
            PagingMode mode = PagingMode.Plain)
        {
            if (showMaxPageCount <= 0)
            {
                return MvcHtmlString.Empty;
            }

            StringBuilder sb = new StringBuilder();

            sb.AppendFormat("<div id=\"kPaging\">");
            if (pageViewData.TotalPageCount > 1)
            {
                if (mode == PagingMode.Detail)
                {
                    sb.AppendFormat("<span style=\"margin:0px 5px;\">第 {0} 页，共{1}页，共{2}条</span>", pageViewData.TotalPageCount < pageViewData.CurrentPage ? 1 : pageViewData.CurrentPage,
                    pageViewData.TotalPageCount, pageViewData.TotalDataCount);
                }

                int startPageNum, endPageNum;

                sb.AppendFormat(PageLinkTemplete, action(1), "首页");
                if (pageViewData.CurrentPage > 1)
                {
                    sb.AppendFormat(PageLinkTemplete, action(pageViewData.CurrentPage - 1), "上一页");
                }

                //第一页
                if (pageViewData.CurrentPage <= 1)
                {
                    startPageNum = 1;
                    endPageNum = showMaxPageCount;
                    if (endPageNum > pageViewData.TotalPageCount)
                    {
                        endPageNum = pageViewData.TotalPageCount;
                    }
                    pageViewData.CurrentPage = 1;
                }
                else if (pageViewData.CurrentPage >= pageViewData.TotalPageCount)//最后一页
                {
                    startPageNum = pageViewData.TotalPageCount - showMaxPageCount + 1;
                    endPageNum = pageViewData.TotalPageCount;
                    if (startPageNum <= 0)
                    {
                        startPageNum = 1;
                    }
                    pageViewData.CurrentPage = pageViewData.TotalPageCount;
                }
                else
                {
                    //当前页区域
                    int regionIndex = 1;
                    regionIndex = (int)Math.Ceiling(pageViewData.CurrentPage * 1.0 / showMaxPageCount);

                    startPageNum = (regionIndex - 1) * showMaxPageCount + 1;
                    endPageNum = regionIndex * showMaxPageCount;

                    //TotalPageCount是否小于endPageNum
                    if (endPageNum > pageViewData.TotalPageCount)
                    {
                        endPageNum = pageViewData.TotalPageCount;
                    }
                }

                for (int i = startPageNum; i <= endPageNum; i++)
                {
                    if (i == pageViewData.CurrentPage)
                    {
                        sb.AppendFormat(CurrentPageLinkTemplete, i);
                    }
                    else
                    {
                        sb.AppendFormat(PageLinkTemplete, action(i), i);
                    }
                }

                if (pageViewData.CurrentPage < pageViewData.TotalPageCount)
                {
                    sb.AppendFormat(PageLinkTemplete, action(pageViewData.CurrentPage + 1), "下一页");
                }

                sb.AppendFormat(PageLinkTemplete, action(pageViewData.TotalPageCount), "末页");
            }

            sb.AppendFormat("</div>");

            return MvcHtmlString.Create(sb.ToString());
        }

最后调用

<style type="text/css">
    #kPaging {
        PADDING-RIGHT: 3px;
        PADDING-LEFT: 3px;
        FONT-SIZE: 0.85em;
        PADDING-BOTTOM: 3px;
        MARGIN: 3px;
        PADDING-TOP: 3px;
        FONT-FAMILY: Tahoma,Helvetica,sans-serif;
        TEXT-ALIGN: center;
    }

        #kPaging .currentPage {
            PADDING-RIGHT: 6px;
            PADDING-LEFT: 6px;
            FONT-WEIGHT: bold;
            PADDING-BOTTOM: 2px;
            COLOR: #000;
            MARGIN-RIGHT: 3px;
            PADDING-TOP: 2px;
        }

        #kPaging .pageLink {
            BORDER-RIGHT: #ccdbe4 1px solid;
            PADDING-RIGHT: 8px;
            BACKGROUND-POSITION: 50% bottom;
            BORDER-TOP: #ccdbe4 1px solid;
            PADDING-LEFT: 8px;
            PADDING-BOTTOM: 2px;
            BORDER-LEFT: #ccdbe4 1px solid;
            COLOR: #0061de;
            MARGIN-RIGHT: 3px;
            PADDING-TOP: 2px;
            BORDER-BOTTOM: #ccdbe4 1px solid;
            TEXT-DECORATION: none;
        }
</style>

<h2>title</h2>
@Html.PagePanel(new PageViewData<Student>(6, 10, 58), i => string.Format("#?page={0}", i), 10)

展示效果：

它的样式我们可以自定义，只要重写#kPaging、.pageLink、.currentPage选择器内容即可。