根据对方提供的URL获取返回的数据流并保存为XML

        /// <summary>
        /// 请求连接，响应得到数据流，生成XML
        /// </summary>
        /// <param name="url">请求url</param>
        /// <param name="path">存放生成XML的路径</param>
        /// <returns></returns>
        public bool DownLoadAndCreateXML(string url, string path)
        {
            try
            {
                WebRequest request = WebRequest.Create(url);
                request.ContentType = "text/xml";
                WebResponse response = request.GetResponse();
                using (StreamWriter write = new StreamWriter(new FileStream(path, FileMode.Create)))
                {
                    using (StreamReader reader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.UTF8))
                    {
                        write.WriteLine(reader.ReadToEnd());
                    }
                }
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }

        /// <summary>
        /// 根据访问URL来返回XML文档流
        /// </summary>
        /// <param name="Url">访问URL</param>
        /// <returns>XML文档流</returns>
        public Stream WriteCardToStream(string Url)
        {
            try
            {
                WebRequest request = WebRequest.Create(Url);
                request.ContentType = "text/xml";
                WebResponse response = request.GetResponse();
                Stream stream = response.GetResponseStream();
                return stream;
            }
            catch (Exception ex)
            {
                return null;
            }
        }

   /// <summary>
        /// MD5加密方式加密
        /// ggh
        /// </summary>
        /// <param name="s">需要加密的字符串</param>
        /// <returns>经过md5加密过的字符串</returns>
        public string MD5(string s)
        {
            byte[] b = Encoding.Default.GetBytes(s);
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] result = md5.ComputeHash(b);
            s = "";
            for (int i = 0; i < result.Length; i++)
            {
                s += result[i].ToString("x").PadLeft(2, '0');
            }
            return s;
        }