长文章自动分页

  ArticlePaing articlePaging = new ArticlePaing();

  LiteralHtml.Text = articlePaging.CoustomPaging("未分页的文章");

#region "Using"



using System;

using System.Text;

using System.Web;

using System.Web.Caching;



#endregion



namespace Teleware.Modules.Articles {



    /// <summary>

    /// 文章内容分页类

    /// </summary>

    public class ArticlePaing {



        #region "Constructor"



        /// <summary>

        /// 构造函数初始一些默认值

        /// </summary>

        public ArticlePaing() {

            ResetCache();

            PageNumber = 1;

            SelectPageStyle = "style='color:red'";

            PageSize = 10;



        }

        #endregion



        #region "Properties"



        /// <summary>

        /// 分页分隔标记

        /// </summary>

        public const string SpiltPageTag = "#Page#";

        /// <summary>

        /// 分页后连接和内容部分模板

        /// </summary>

        public const string PagingTemplate = @"<table width='100%' >



                                            <tr><td style='height:300px' valign='top'>#Content#</td></tr>



                                            <tr><td align='center'>#NavigatorUrl#</td></tr>



                                            </table>";



        /// <summary>

        /// 文章内容缓存Key

        /// </summary>

        private const string ContentCacheKey = "ContentCacheKey";

        /// <summary>

        /// 页面大小|自动分页时指每页字符数

        /// </summary>

        public int PageSize { get; set; }

        /// <summary>

        /// 总记录数

        /// </summary>

        public int TotalCount { get; set; }

        /// <summary>

        /// 页号

        /// </summary>

        public int PageNumber { get; set; }

        /// <summary>

        /// 页数

        /// </summary>

        public int PageCount { get; set; }

        /// <summary>

        /// 选择页面样式

        /// </summary>

        public string SelectPageStyle { get; set; }



        #endregion



        #region "Public Method"



        public string CoustomPaging(string content) {



            TotalCount = GetPages(content).Length;

            //计算出总页数

            PageCount = TotalCount % PageSize == 0 ? TotalCount / PageSize : TotalCount / PageSize + 1;



            string articlePage = HttpContext.Current.Request["ArticlePage"];



            string isLeave = HttpContext.Current.Request["IsLeft"];



            //分页模板,主要是用于分页内容和分页链接的布局



            string template = PagingTemplate;



            if (!string.IsNullOrEmpty(articlePage)) {

                PageNumber = int.Parse(articlePage);

            }

            if (PageNumber > TotalCount) {

                PageNumber = TotalCount;

            }

            if (PageNumber != -1 && PageNumber < 1) {

                PageNumber = 1;

            }

            //如果余下参数不为空直接返回当前页余下的所有文章内容

            if (isLeave != null) {

                return template.Replace("#Content#", GetLeavePage(content)).Replace("#NavigatorUrl#", "");

            }

            return template.Replace("#Content#", GetPages(content)[PageNumber - 1]).Replace("#NavigatorUrl#", CreateNavigatorUrl(content));

        }



        #endregion



        #region "Private Method"



        /// <summary>

        /// 获取所有页面数据(并将数据缓存)

        /// </summary>

        /// <param name="content"></param>

        /// <returns></returns>

        private string[] GetPages(string content) {



            Cache cache = HttpContext.Current.Cache;

            if (cache[ContentCacheKey] == null) {

                string[] Pages = content.Split(new string[] { SpiltPageTag }, StringSplitOptions.RemoveEmptyEntries);

                cache[ContentCacheKey] = Pages;

                return Pages;

            } else {

                return cache[ContentCacheKey] as string[];

            }

        }



        /// <summary>

        /// 获取页面跳转的Url

        /// </summary>

        /// <param name="content">文章内容</param>

        /// <returns></returns>

        private string CreateNavigatorUrl(string content) {

            StringBuilder sb = new StringBuilder();



            //计算出当前文章所在页,已经取出所在组开始索引和结束索引

            int start = 0, end = 0;

            for (int j = 0; j < PageCount; j++) {

                //判断文章所在页区间

                if (PageNumber > j * PageSize && PageNumber <= (j + 1) * PageSize) {



                    start = j * PageSize;

                    //如果是最后一页,结束索引则等于总记录数

                    if (j == PageCount - 1) {

                        end = TotalCount;

                    } else {

                        end = (j + 1) * PageSize;

                    }

                }

            }



            //上一页

            if (PageNumber > 1) {

                sb.Append(GetPreviousUrl());

            }

            //中间部分

            for (; start < end; start++) {



                //设置选中样式    

                if (PageNumber == start + 1) {



                    sb.Append(GetAppointUrl(start + 1, SelectPageStyle));

                } else {



                    sb.Append(GetAppointUrl(start + 1, string.Empty));

                }

            }

            if (PageNumber < TotalCount) {

                //下一页

                sb.Append(GetNextUrl());

                //剩下所有页

                sb.Append(GetLeaveUrl());

            }



            return sb.ToString();

        }



        /// <summary>

        /// 生成链接Url

        /// </summary>

        /// <param name="arg1">参数</param>

        /// <param name="strShow">链接显示的文字</param>

        private string CreateLink(object url, string style, string strShow) {

            return string.Format(" <a href='{0}' {1} > {2} </a>", url, style, strShow);

        }



        /// <summary>

        /// 获取下页链接

        /// </summary>

        private string GetNextUrl() {

            return CreateLink(string.Format("{0}&ArticlePage={1}", GetFirstRequestUrl(), PageNumber + 1), string.Empty, "下一页");

        }



        /// <summary>

        /// 获取上页链接

        /// </summary>

        private string GetPreviousUrl() {

            return CreateLink(string.Format("{0}&ArticlePage={1}", GetFirstRequestUrl(), PageNumber - 1), string.Empty, "上一页");

        }



        /// <summary>

        /// 获取余下页链接

        /// </summary>

        private string GetLeaveUrl() {

            return CreateLink(string.Format("{0}&ArticlePage={1}&IsLeft=true", GetFirstRequestUrl(), PageNumber), string.Empty, "余下页");

        }



        /// <summary>

        /// 获取指定页链接

        /// </summary>

        /// <param name="PageNumber">页号</param>

        /// <param name="selectStyle">链接样式</param>

        private string GetAppointUrl(int PageNumber, string selectStyle) {

            return CreateLink(string.Format("{0}&ArticlePage={1}", GetFirstRequestUrl(), PageNumber), selectStyle, "[" + PageNumber + "]");

        }



        /// <summary>

        /// 获取从当前页开始剩下的所有页面

        /// </summary>

        /// <param name="content"></param>

        /// <param name="PageNumer"></param>

        /// <returns></returns>

        private string GetLeavePage(string content) {



            StringBuilder sb = new StringBuilder();

            for (int i = PageNumber; i < GetPages(content).Length; i++) {

                sb.Append(GetPages(content)[i]);

            }

            return sb.ToString();

        }



        /// <summary>

        /// 如果请求地址无页分页参数,则清空缓存

        /// </summary>

        private void ResetCache() {

            if (HttpContext.Current.Request.Url.ToString().IndexOf("&ArticlePage=") == -1) {

                Cache cache = HttpContext.Current.Cache;

                if (cache[ContentCacheKey] != null) {

                    cache.Remove(ContentCacheKey);

                }

            }

        }

        /// <summary>

        /// 获取第一请求连接

        /// </summary>

        /// <returns></returns>

        private string GetFirstRequestUrl() {

            string url = HttpContext.Current.Request.Url.ToString();

            if (url.IndexOf("&ArticlePage=") != -1) {

                url = url.Substring(0, url.IndexOf("&ArticlePage="));

            }

            return url;

        }



        #endregion

    }

}