//传入文件路径
        private string getMD5(string path)
        {
            MD5CryptoServiceProvider get_md5 = new MD5CryptoServiceProvider();
            FileStream get_file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
            byte[] hash_byte = get_md5.ComputeHash(get_file);
            string result = BitConverter.ToString(hash_byte);
            result = result.Replace("-", "");
            get_file.Close();
            return result;
        }