Windows Form app find Link on Web

问题

I need to create a method that find the newest version of application on a website (Hudson server) and allow to download it.

till now I use regex to scan all the HTML and find the href tags and search for the string I wish to.

I want to know if there is a simplest way to do so. I attached the code I use today:

namespace SDKGui
{
    public struct LinkItem
    {
        public string Href;
        public string Text;

    public override string ToString()
    {
        return Href;
    }
}

static class LinkFinder
{
    public static string Find(string file)
    {
        string t=null;
        List<LinkItem> list = new List<LinkItem>();

        // 1.
        // Find all matches in file.
        MatchCollection m1 = Regex.Matches(file, @"(<a.*?>.*?</a>)",
            RegexOptions.Singleline);


        // 2.
        // Loop over each match.
        foreach (Match m in m1)
        {
            string value = m.Groups[1].Value;
            LinkItem i = new LinkItem();

            // 3.
            // Get href attribute.
            Match m2 = Regex.Match(value, @"href=\""(.*?)\""",
            RegexOptions.Singleline);
            if (m2.Success)
            {
                i.Href = m2.Groups[1].Value;
            }

            // 4.
            // Remove inner tags from text.
            t = Regex.Replace(value, @"\s*<.*?>\s*", "",
            RegexOptions.Singleline);

            if (t.Contains("hms_sdk_tool_"))
            {
                i.Text = t;
                list.Add(i);
                break;
            }



        }
        return t;
    }

}
}

回答1:

It is easy to collect all href values and filter against any of your conditions using HtmlAgilityPack. The following method shows how to access a page, get all <a> tags, and return a list of all href values containing hms_sdk_tool_:

private List<string> HtmlAgilityCollectHrefs(string url)
{
    var webGet = new HtmlAgilityPack.HtmlWeb();
    var doc = webGet.Load(url);
    var a_nodes = doc.DocumentNode.SelectNodes("//a");
    return a_nodes.Select(p => p.GetAttributeValue("href", "")).Where(n => n.Contains("hms_sdk_tool_")).ToList();
}

Or, if you are interested in 1 return string, use

private string GetLink(string url)
{
    var webGet = new HtmlAgilityPack.HtmlWeb();
    var doc = webGet.Load(url);
    var a_nodes = doc.DocumentNode.SelectNodes("//a");
    return a_nodes.Select(p => p.GetAttributeValue("href", "")).Where(n => n.Contains("hms_sdk_tool_")).FirstOrDefault();
}

来源：https://stackoverflow.com/questions/30459779/windows-form-app-find-link-on-web

标签

regex

winforms

webclient-download