下载后如何加载页面而不先将其保存到文件

Question

I'd like to parse the following in a webpage:

<h1 class="eTitle">bla bla bla v1.0</h1>

I want to display "bla bla bla v.1.0" in a textbox that I created using WPF. My code is the followind, but it display nothing in the textbox when I click the button.

private void Button_Click_1(object sender, RoutedEventArgs e)
    {
           WebClient webClient = new WebClient();
           webClient.Encoding = Encoding.UTF8;
           webClient.DownloadFile("http://blablabla.com", "blabla.htm");

        HtmlDocument htmldoc = new HtmlDocument();
        htmldoc.Load("blabla.htm");
        var titlenode = htmldoc.DocumentNode.SelectSingleNode("blabla");

        textbox1.Text = "" + titlenode;
    }
private void textbox1_TextChanged(object sender, TextChangedEventArgs e)
    {
    }

Actually I'm saving the page into a .htm file and reading from it. Can I avoid doing this?

Answer 1

为了避免下载文件，可以使用webClient.DownloadString("http://blablabla.com/blabla.htm");

Answer 2

You're XPath expression to get the node is not correct.

If you want to get single h1 node use this

var titlenode = htmldoc.DocumentNode.SelectSingleNode("//h1");

If you want to get single h1 with title eTitle node use this

var titlenode = htmldoc.DocumentNode.SelectSingleNode("//h1[@title = 'eTitle']");

For more see this page .

Then you have to access the node value and display it.

Answer 3

Why not just use an HttpWebRequest to pull the html file itself?

Source: Get html source of web page using HttpWebRequest class

private string getHtml(string url)
{
    if(String.IsNullOrWhiteSpace(url)) { return; }
    // Create Web Request
    HttpWebRequest myWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
    // Set GET method
    myWebRequest.Method = "GET";
    // Get a response
    HttpWebResponse myWebResponse = (HttpWebResponse)myWebRequest.GetResponse();
    // Open a Stream to read the response
    StreamReader myWebSource = new StreamReader(myWebResponse.GetResponseStream());
    // Create a string to store the response
    string myPageSource = string.Empty;
    myPageSource= myWebSource.ReadToEnd();
    // Close the stream
    myWebResponse.Close();
    // Return the string
    return myPageSource;
}

Then using Google homepage as an example, you call string htmlPage = getHtml("http://www.google.ca");