C#抓取网络图片保存到本地的实现方法

System.Net.WebClient myWebClient = new System.Net.WebClient();
  //将头像保存到服务器
     string virPath = "/Uploads/AppImage/" + user.Id + "/";
     CreateDir(virPath);
     string fileName = Guid.NewGuid().ToString() + ".png";
     myWebClient.DownloadFile(headimgurl,System.Web.HttpContext.Current.Request.PhysicalApplicationPath + virPath + fileName);
     user.Portrait = virPath + fileName;

#region 创建目录
  /// <summary>
  /// 创建目录
  /// </summary>
  /// <param name="dir">要创建的目录路径包括目录名</param>
  public static void CreateDir(string dir)
  {
   if (dir.Length == 0) return;
   if (!Directory.Exists(System.Web.HttpContext.Current.Request.PhysicalApplicationPath + "" + dir))
    Directory.CreateDirectory(System.Web.HttpContext.Current.Request.PhysicalApplicationPath + "" + dir)
     ;
  }
  #endregion