C＃嘗試使用XmlNode閱讀頁面

Question

因此，我正在嘗試從最低價格到最高價格閱讀Steam商店頁面。 我有所需的URL，並且編寫了一些過去可以使用但不再可用的代碼。 我花了幾天的時間來解決此問題，但似乎無法找到問題。

鏈接我正在嘗試閱讀。

這是代碼。

    //List of items from the Steam market from lowest to highest
    private void priceFromMarket(int StartPage)
    {
        if (valueList.Count != 0)
        {
            valueList.Clear();
            numList.Clear();
            nameList.Clear();
        }
        string pageContent = null;
        string results_html = null;
        try
        {
            HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create("http://steamcommunity.com/market/search/render/?query=appid:730&start=" + StartPage.ToString() + "&sort_column=price&sort_dir=asc&count=100&currency=1&l=english");
            HttpWebResponse myRes = (HttpWebResponse)myReq.GetResponse();
            using (StreamReader sr = new StreamReader(myRes.GetResponseStream()))
            {
                pageContent = sr.ReadToEnd();
            }
        }
        catch { Thread.Sleep(30000); priceFromMarket(StartPage); }
        if (pageContent == null) { priceFromMarket(StartPage); }
        try
        {
            JObject user = JObject.Parse(pageContent);
            bool success = (bool)user["success"];
            if (success)
            {
                results_html = (string)user["results_html"];
                string data = results_html;
                data = "<root>" + data + "</root>";
                XmlDocument document = new XmlDocument();
                document.LoadXml(System.Net.WebUtility.HtmlDecode(data));
                XmlNode rootnode = document.SelectSingleNode("root");
                XmlNodeList items = rootnode.SelectNodes("./a/div");
                foreach (XmlNode node in items)
                {
                    //This does not work anymore!
                    //The try fails here at line 574!
                    string value = node.SelectSingleNode("./div[contains(concat(' ', @class, ' '), ' market_listing_their_price ')]/span/span").InnerText;
                    string num = node.SelectSingleNode("./div[contains(concat(' ', @class, ' '), ' market_listing_num_listings ')]/span/span").InnerText;
                    string name = node.SelectSingleNode("./div/span[contains(concat(' ', @class, ' '), ' market_listing_item_name ')]").InnerText;
                    valueList.Add(value); //Lowest price for the item
                    numList.Add(num); //Volume of that item
                    nameList.Add(name); //Name of that item
                }
            }
            else { Thread.Sleep(60000); priceFromMarket(StartPage); }
        }
        catch { Thread.Sleep(60000); priceFromMarket(StartPage); }
    }

Answer 1

將HTML解析為XML永遠都不可靠，因為HTML的格式必須正確才能正確解析...

為了在C＃中解析HTML，我更喜歡使用CSQuery https://www.nuget.org/packages/CsQuery/

它使您可以通過c＃解析HTML，類似於通過jquery解析HTML。

另一種方法是HTML Agility Pack，您可以在不更改大量代碼的情況下使用它。其功能類似於System.Xml.XmlDocument庫。