欢迎使用CSDN-markdown编辑器

  public static string _defaultUserAgent = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 UBrowser/5.7.15319.202 Safari/537.36";   //定义默认浏览器类型

    public static int _timeout = 35000;    //定义请求超时时间

    public void DoGetImage(string url, string path)        {            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);            req.ServicePoint.Expect100Continue = false;            req.Method = "GET";            req.KeepAlive = true;            req.UserAgent = _defaultUserAgent;            req.Timeout = _timeout;//3秒            Uri aurl = new Uri(url);            //通过url 获取域名           // string host = "img.alicdn.com";            req.Host = aurl.Host;            req.Headers.Add("Accept-Encoding", "gzip,deflate");            //req.Headers.Add("Accept", "image/webp,image/*,*/*;q=0.8");            req.Headers.Add("Accept-Language", "zh-CN,zh;q=0.8");            string imgType = "jpeg";//通过url 获取图片的扩展名            imgType = url.Substring(url.LastIndexOf('.')+1);            if (imgType == "jpg") imgType = "jpeg";            req.ContentType = "image/" + imgType;            Random rad = new Random();            int rnum = rad.Next(1000, 9999);            path += "/" + DateTime.Now.ToString("HHmmssfff") + rnum + "." + imgType;            using (HttpWebResponse rsp = (HttpWebResponse)req.GetResponse())            {                System.IO.Stream stream = null;                try                {                    // 以字符流的方式读取HTTP响应                    using (stream = rsp.GetResponseStream())                    {                        using (Image am = Image.FromStream(stream))                        {                            am.Save(path);                            am.Dispose();                        }                        stream.Close();                        stream.Dispose();                        stream = null;                    }                }                finally                {                    // 释放资源                    if (stream != null) stream.Close();                    if (rsp != null) rsp.Close();                  }            }            req = null;        }

调用：
DoGetImage(“http://img.alicdn.com/imgextra/i1/1736826123/1736826123.jpg“, “D://imgs//”);