无法在 .net 中下载网页

Question

我做了一批解析 gearbest.com 的 html 页面以提取项目数据（示例链接link）。直到 2-3 周前网站更新后，它才有效。所以我无法下载要解析的页面，我也不知道为什么。在更新之前，我确实使用 HtmlAgilityPack 请求了以下代码。HtmlWeb web = new HtmlWeb();    HtmlDocument doc = null;    doc = web.Load(url); //now this the point where is throw the exception我在没有框架的情况下尝试过，并在请求中添加了一些日期HttpWebRequest request = (HttpWebRequest) WebRequest.Create("https://it.gearbest.com/tv-box/pp_009940949913.html");request.Credentials = CredentialCache.DefaultCredentials;request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36";request.ContentType = "text/html; charset=UTF-8";request.CookieContainer = new CookieContainer();request.Headers.Add("accept-language", "it-IT,it;q=0.9,en-US;q=0.8,en;q=0.7");request.Headers.Add("accept-encoding", "gzip, deflate, br");request.Headers.Add("upgrade-insecure-requests", "1");request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8";request.CookieContainer = new CookieContainer();Response response = request.GetResponse();  //exception例外是：IOException：无法从传输连接读取数据SocketException: 无法建立连接。如果我尝试请求主页 ( https://it.gearbest.com ) 它可以工作。你认为问题是什么？

Answer 1

出于某种原因，它不喜欢提供的用户代理。如果您省略设置UserAgent一切正常

HttpWebRequest request = (HttpWebRequest) WebRequest.Create("https://it.gearbest.com/tv-box/pp_009940949913.html");

request.Credentials = CredentialCache.DefaultCredentials;

//request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36";

request.ContentType = "text/html; charset=UTF-8";

另一种解决方案是设置request.Connection为随机字符串（但不是keep-aliveor close）

request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36";

request.Connection = "random value";

它也有效，但我无法解释原因。

Answer 2

也许值得尝试一下...

HttpRequest.KeepAlive = false; 

HttpRequest.ProtocolVersion = HttpVersion.Version10;