C#抓取网络图片保存到本地

public Bitmap Get_img()
        {
            Bitmap img = null;
            HttpWebRequest req;
            HttpWebResponse res = null;
                try
                {
                    System.Uri httpUrl = new System.Uri("http://xxx.com/xxx.png ");
                    req = (HttpWebRequest)(WebRequest.Create(httpUrl));
                    req.Timeout = 180000; //设置超时值10秒
                       req.UserAgent = "XXXXX";
                    req.Accept = "XXXXXX";
                    req.Method = "GET";
                    res = (HttpWebResponse)(req.GetResponse());

                       img = new Bitmap(res.GetResponseStream());//获取图片流

                    img.Save(@"E:/" + DateTime.Now.ToFileTime().ToString() + ".png");//随机名
                }

            catch (Exception ex)
            {
                 string aa= ex.Message;
            }
            finally
            {
                res.Close();
            }
                 return img;
    }</pre>