c# - 我想用 HtmlAgilityPack 检索 html 元素的宽度和高度

Question

HtmlAgilityPack如何使用我这样做来检索 img 元素的宽度和高度..

    HtmlAgilityPack.HtmlAttribute width = link.Attributes["width"];
    HtmlAgilityPack.HtmlAttribute height = link.Attributes["height"];

但在大多数情况下，宽度和高度为空。如何获得css的高度和宽度？

Answer 1

此页面中的基础：页面

public sealed class UtilParserHTML
{

    //Private Fields
    private Uri Uri;
    private Stream StreamPage;
    private HttpWebRequest HttpRequest;
    private HttpWebResponse HttpResponse;

    //Public Fields
    public HtmlDocument HtmlDocument { private set; get; }

    public UtilParserHTML()
    {
        if (this.HtmlDocument == null)
            HtmlDocument = new HtmlDocument();
    }

    public void LoadHTMLPage(string UrlPage)
    {
        if (string.IsNullOrEmpty(UrlPage))
            throw new ArgumentNullException("");

        CookieContainer cookieContainer = new CookieContainer();

        this.Uri = new Uri(UrlPage);
        this.HttpRequest = (HttpWebRequest)WebRequest.Create(UrlPage);
        this.HttpRequest.Method = WebRequestMethods.Http.Get;       
        this.HttpRequest.CookieContainer = cookieContainer;
        this.HttpResponse = (HttpWebResponse)this.HttpRequest.GetResponse();
        this.StreamPage = this.HttpResponse.GetResponseStream();
        this.HtmlDocument.Load(StreamPage);
    }

    public void LoadHTMLPage(FileStream StreamPage)
    {
        if (StreamPage == null)
            throw new ArgumentNullException("");

        HtmlDocument.Load(StreamPage);
    }

    public HtmlNodeCollection GetNodesByExpression(string XPathExpression)
    {
        if (string.IsNullOrEmpty(XPathExpression))
            throw new ArgumentNullException("");

        return this.HtmlDocument.DocumentNode.SelectNodes(XPathExpression);
    }

使用XPath在 html 中导航。在这种情况下，我使用了这个 Xpath 表达式： //div[@class='arrowRibbon'] //img

看： ...

this.ParserHTML.LoadHTMLPage("http://www.img.com.br/default.aspx");
            HtmlNodeCollection HtmlNodeCollectionResult = this.ParserHTML.GetNodesByExpression(Page.XPathExpression);

            if (HtmlNodeCollectionResult != null)
            {
                foreach (HtmlNode NodeResult in HtmlNodeCollectionResult)
                {
                    var src = NodeResult.Attributes["src"].Value;
                }
            }

...

编辑

看看这个带有宽度和高度的完整示例：

this.ParserHTML.LoadHTMLPage("http://www.w3schools.com/tags/tag_img.asp");
            HtmlNodeCollection HtmlNodeCollectionResult = this.ParserHTML.GetNodesByExpression("//div[@class='tryit_ex'] //img");

            if (HtmlNodeCollectionResult != null)
            {
                foreach (HtmlNode NodeResult in HtmlNodeCollectionResult)
                {
                    var src = NodeResult.Attributes["src"].Value;
                    var w = NodeResult.Attributes["width"].Value;
                    var h = NodeResult.Attributes["height"].Value;
                }
            }

希望这有帮助。