.NET常用工具类（Utils.cs）

        /**//// <summary>
        /// MD5函数
        /// </summary>
        /// <param name="str">原始字符串</param>
        /// <returns>MD5结果</returns>
        public static string MD5(string str)
        {
            byte[] b = Encoding.Default.GetBytes(str);
            b = new MD5CryptoServiceProvider().ComputeHash(b);
            string ret = "";
            for(int i = 0; i < b.Length; i++)
                ret += b[i].ToString("x").PadLeft(2,'0');
            return ret;
        }

        /**//// <summary>
        /// SHA256函数
        /// </summary>
        /// /// <param name="str">原始字符串</param>
        /// <returns>SHA256结果</returns>
        public static string SHA256(string str)
        {
            byte[] SHA256Data = Encoding.UTF8.GetBytes(str);
            SHA256Managed Sha256 = new SHA256Managed();
            byte[] Result = Sha256.ComputeHash(SHA256Data);
            return Convert.ToBase64String(Result);  //返回长度为44字节的字符串
        }

        /**//// <summary>
        /// 检测是否符合email格式
        /// </summary>
        /// <param name="strEmail">要判断的email字符串</param>
        /// <returns>判断结果</returns>
        public static bool IsValidEmail(string strEmail)
        {
            return Regex.IsMatch(strEmail, @"^([/w-/.]+)@((/[[0-9]{1,3}/.[0-9]{1,3}/.[0-9]{1,3}/.)|(([/w-]+/.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(/]?)$");
        }

        public static bool IsValidDoEmail(string strEmail)
        {
            return Regex.IsMatch(strEmail, @"^@((/[[0-9]{1,3}/.[0-9]{1,3}/.[0-9]{1,3}/.)|(([/w-]+/.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(/]?)$");
        }

        /**//// <summary>
        /// 检测是否是正确的Url
        /// </summary>
        /// <param name="strUrl">要验证的Url</param>
        /// <returns>判断结果</returns>
        public static bool IsURL(string strUrl)
        {
            return Regex.IsMatch(strUrl, @"^(http|https)/://([a-zA-Z0-9/./-]+(/:[a-zA-Z0-9/.&%/$/-]+)*@)*((25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])/.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)/.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)/.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])|localhost|([a-zA-Z0-9/-]+/.)*[a-zA-Z0-9/-]+/.(com|edu|gov|int|mil|net|org|biz|arpa|info|name|pro|aero|coop|museum|[a-zA-Z]{1,10}))(/:[0-9]+)*(/($|[a-zA-Z0-9/./,/?/'///+&%/$#/=~_/-]+))*$");
        }

        public static string GetEmailHostName(string strEmail)
        {
            if (strEmail.IndexOf("@") < 0)
            {
                return "";
            }
            return strEmail.Substring(strEmail.LastIndexOf("@")).ToLower();
        }

        /**//// <summary>
        /// 检测是否有Sql危险字符
        /// </summary>
        /// <param name="str">要判断字符串</param>
        /// <returns>判断结果</returns>
        public static bool IsSafeSqlString(string str)
        {

            return !Regex.IsMatch(str, @"[-|;|,|//|/(|/)|/[|/]|/}|/{|%|@|/*|!|/']"); 
        }

        /**//// <summary>
        /// 转换为简体中文
        /// </summary>
        public static string ToSChinese(string str)
        {
            return Strings.StrConv(str, VbStrConv.SimplifiedChinese, 0) ;
        }

        /**//// <summary>
        /// 转换为繁体中文
        /// </summary>
        public static string ToTChinese(string str)
        {
            return Strings.StrConv(str, VbStrConv.TraditionalChinese, 0);
        }

        /**//// <summary>
        /// 返回 HTML 字符串的编码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>编码结果</returns>
        public static string HtmlEncode(string str)
        {
            return HttpUtility.HtmlEncode(str);
        }

        /**//// <summary>
        /// 返回 HTML 字符串的解码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>解码结果</returns>
        public static string HtmlDecode(string str)
        {
            return HttpUtility.HtmlDecode(str);
        }

        /**//// <summary>
        /// 返回 URL 字符串的编码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>编码结果</returns>
        public static string UrlEncode(string str)
        {
            return HttpUtility.UrlEncode(str);
        }

        /**//// <summary>
        /// 返回 URL 字符串的编码结果
        /// </summary>
        /// <param name="str">字符串</param>
        /// <returns>解码结果</returns>
        public static string UrlDecode(string str)
        {
            return HttpUtility.UrlDecode(str);
        }

        /**//// <summary>
        /// 写cookie值
        /// </summary>
        /// <param name="strName">名称</param>
        /// <param name="strValue">值</param>
        /// <param name="strValue">过期时间(分钟)</param>
        public static void WriteCookie(string strName, string strValue, int expires)
        {
            HttpCookie cookie = HttpContext.Current.Request.Cookies[strName];
            if (cookie == null)
            {
                cookie = new HttpCookie(strName);
            }
            cookie.Value = strValue;
            cookie.Expires = DateTime.Now.AddMinutes(expires);
            HttpContext.Current.Response.AppendCookie(cookie);

        }

        /**//// <summary>
        /// 读cookie值
        /// </summary>
        /// <param name="strName">名称</param>
        /// <returns>cookie值</returns>
        public static string GetCookie(string strName)
        {
            if (HttpContext.Current.Request.Cookies != null && HttpContext.Current.Request.Cookies[strName] != null)
            {
                return HttpContext.Current.Request.Cookies[strName].Value.ToString();
            }

            return "";
        }