public string GetMD5(string myString)
        {
            //return BitConverter.ToString(MD5.Create().ComputeHash(Encoding.Default.GetBytes(myString))).Replace("-", ""); 错的错的错的！！！
            MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
            byte[] data = md5Hasher.ComputeHash(Encoding.UTF8.GetBytes(myString));

            StringBuilder sBuilder = new StringBuilder();
            for (int i = 0; i < data.Length; i++)
            {
                sBuilder.Append(data[i].ToString("x2"));
            }
            return sBuilder.ToString();
        }