/// <summary>
        /// 获取大写的MD5签名结果
        /// </summary>
        /// <param name="encypStr"></param>
        /// <param name="charset"></param>
        /// <returns></returns>
        public static string GetMD5(string encypStr, string charset)
        {
            string retStr;
            MD5CryptoServiceProvider m5 = new MD5CryptoServiceProvider();

            //创建md5对象
            byte[] inputBye;
            byte[] outputBye;

            //使用GB2312编码方式把字符串转化为字节数组．
            try
            {
                inputBye = Encoding.GetEncoding(charset).GetBytes(encypStr);
            }
            catch (Exception ex)
            {
                inputBye = Encoding.GetEncoding("GB2312").GetBytes(encypStr);
            }       
            outputBye = m5.ComputeHash(inputBye);
            m5.Clear();
            retStr = System.BitConverter.ToString(outputBye);
            retStr = retStr.Replace("-", "").ToLower();
            return retStr;
        }

        public static string md5(string str)
        {
            try
            {
                MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
                byte[] bytValue, bytHash;
                bytValue = System.Text.Encoding.UTF8.GetBytes(str);
                bytHash = md5.ComputeHash(bytValue);
                md5.Clear();
                string sTemp = "";
                for (int i = 0; i < bytHash.Length; i++)
                {
                    sTemp += bytHash[i].ToString("X").PadLeft(2, ‘0‘);
                }
                str = sTemp.ToLower();
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }

            return str;
        }