从某个网址下载图片到特定的路径

    WebRequest wreq = WebRequest.Create("http://mmbiz.qpic.cn/mmbiz/8jauNKmzssNSibuH14RnI1EOLJhRMLDgrA4nfVCGLhHj2AGmGZrI0ms0ibbGNluhojItGpMQv9S4v754zwaJ9kxQ/0");
            HttpWebResponse wresp = (HttpWebResponse)wreq.GetResponse();
            Stream s = wresp.GetResponseStream();
            System.Drawing.Image img;
            img = System.Drawing.Image.FromStream(s);
            string name=DateTime.Now.ToString("ddHHmmssffff");
            img.Save("D:\" + name+".jpg");