How to get img/src or a/hrefs using Html Agility Pack?

问题

I want to use the HTML agility pack to parse image and href links from a HTML page,but I just don't know much about XML or XPath.Though having looking up help documents in many web sites,I just can't solve the problem.In addition,I use C# in VisualStudio 2005.And I just can't speak English fluently,so,I will give my sincere thanks to the one can write some helpful codes.

回答1:

The first example on the home page does something very similar, but consider:

 HtmlDocument doc = new HtmlDocument();
 doc.Load("file.htm"); // would need doc.LoadHtml(htmlSource) if it is not a file
 foreach(HtmlNode link in doc.DocumentElement.SelectNodes("//a[@href"])
 {
    string href = link["href"].Value;
    // store href somewhere
 }

So you can imagine that for img@src, just replace each a with img, and href with src. You might even be able to simplify to:

 foreach(HtmlNode node in doc.DocumentElement
              .SelectNodes("//a/@href | //img/@src")
 {
    list.Add(node.Value);
 }

For relative url handling, look at the Uri class.

回答2:

The example and the accepted answer is wrong. It doesn't compile with the latest version. I try something else:

    private List<string> ParseLinks(string html)
    {
        var doc = new HtmlDocument(); 
        doc.LoadHtml(html);
        var nodes = doc.DocumentNode.SelectNodes("//a[@href]");
        return nodes == null ? new List<string>() : nodes.ToList().ConvertAll(
               r => r.Attributes.ToList().ConvertAll(
               i => i.Value)).SelectMany(j => j).ToList();
    }

This works for me.

回答3:

Maybe I am too late here to post an answer. The following worked for me:

var MainImageString  = MainImageNode.Attributes.Where(i=> i.Name=="src").FirstOrDefault();

回答4:

You also need to take into account the document base URL element (<base>) and protocol relative URLs (for example //www.foo.com/bar/).

For more information check:

<base>: The Document Base URL element page on MDN
The Protocol-relative URL article by Paul Irish
What are the recommendations for html tag? discussion on StackOverflow
Uri Constructor (Uri, Uri) page on MSDN
Uri class doesn't handle the protocol-relative URL discussion no StackOverflow

回答5:

var htmlDoc = new HtmlDocument();
htmlDoc.LoadHtml(html);

string name = htmlDoc.DocumentNode
    .SelectNodes("//td/input")
    .First()
    .Attributes["value"].Value;

Source: https://html-agility-pack.net/select-nodes

来源：https://stackoverflow.com/questions/4835868/how-to-get-img-src-or-a-hrefs-using-html-agility-pack

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