一段手动分页代码

最近在参考Discuz.nt的源码，虽说他们的这种模式比较另类，或者不容易接受(个人感觉)，不过还是有蛮多实用的代码，就像这段手工分页代码，参考了下下。

/**//// <summary>
        /// 获得页码显示链接
        /// </summary>
        /// <param name="curPage">当前页数</param>
        /// <param name="countPage">总页数</param>
        /// <param name="url">超级链接地址</param>
        /// <param name="extendPage">周边页码显示个数上限</param>
        /// <returns>页码html</returns>
        public static string GetPageNumbers(int curPage, int countPage, string url, int extendPage)
        {
            int startPage = 1;
            int endPage = 1;

            if(url.IndexOf("?") > 0)
            {
                url = url + "&";
            }
            else
            {
                url = url + "?";
            }

            string t1 = "<a href=\"" + url + "&page=1" + "\">&laquo;</a>&nbsp;";
            string t2 = "<a href=\"" + url + "&page=" + countPage + "\">&raquo;</a>&nbsp;";

            if(countPage < 1) countPage = 1;
            if(extendPage < 3) extendPage = 2;
            
            if(countPage > extendPage)
            {
                if(curPage - (extendPage / 2) > 0)
                {
                    if(curPage + (extendPage / 2) < countPage)
                    {
                        startPage = curPage - (extendPage / 2);
                        endPage = startPage + extendPage - 1;
                    }
                    else
                    {
                        endPage = countPage;
                        startPage = endPage - extendPage + 1;
                        t2 = "";
                    }
                }
                else
                {
                    endPage = extendPage;
                    t1 = "";
                }
            }
            else
            {
                startPage = 1;
                endPage = countPage;
                t1 = "";
                t2 = "";
            }
            
            StringBuilder s = new StringBuilder("");
            
            s.Append(t1);
            for (int i = startPage; i <= endPage; i++)
            {
                if (i == curPage)
                {
                    s.Append("&nbsp;");
                    s.Append(i);
                    s.Append("&nbsp;");
                }
                else
                {
                    s.Append("&nbsp;<a href=\"");
                    s.Append(url);
                    s.Append("page=");
                    s.Append(i);
                    s.Append("\">");
                    s.Append(i);
                    s.Append("</a>&nbsp;");
                }
            }
            s.Append(t2);

            return s.ToString();
        }

注：源代码出自Discuz.NET 1.0