将流保存成文件

private static void downfile(string filepath)
        {
            int count = 0;
            HttpWebRequest request;
            HttpWebResponse response;
            string name = filepath.Substring(filepath.IndexOf("interface/")+10);
            string filename = Application.StartupPath + "\\" + name;
            if (File.Exists(filename))
            {
                File.Delete(filename);
            }
            request = (HttpWebRequest)WebRequest.Create(filepath);
            response = (HttpWebResponse)request.GetResponse();
            if (response.StatusCode == HttpStatusCode.OK)
                Console.WriteLine(" 获取状态: {0}", response.StatusDescription);
            // Releases the resources of the response.

            Stream responseStream = response.GetResponseStream();
            //StreamReader reader = new StreamReader(responseStream, Encoding.GetEncoding("ASCII"));
            //Console.WriteLine(reader.ReadToEnd());
            StreamReader sr = new StreamReader(responseStream, System.Text.Encoding.UTF8);
            StreamWriter sw = new StreamWriter(filename, true, System.Text.Encoding.UTF8);
          
            while (sr.Peek() >= 0)
            {
                count += 1;
                string xinxi = sr.ReadLine();
                Console.WriteLine(count.ToString()+". "+xinxi);
                sw.WriteLine(xinxi);
                //sw.Write(sr.ReadToEnd());
            }
            sw.Close();

            sr.Close();
                  

        }