WebClient 下载图片(文件)

 public static string SaveImage(string url, string newfilename)
 {
       WebClient mywebclient = new WebClient();
       try
       {
           mywebclient.DownloadFile(url, ConfigurationManager.AppSettings["SaveImgPath"] +"/" + newfilename);
       }
       catch (IOException ex)
       {
           throw new Exception("未找到图片:" + url + "   Message:" + ex.Message);
       }
       catch (Exception ex)
       {
           throw new Exception("未找到图片:" + url + "   Message:" + ex.Message);
       }
       return newfilename;
 }