extract text content from web page using asp.net web form
Question
i'm trying the load a page to may asp.net web form and extract only the text from it and display the extracted text in an Areatext
like this:
and my code is:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
#form1 {
height: 500px;
width: 1199px;
}
.auto-style1 {}
#TextArea1 {
height: 288px;
width: 1157px;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<asp:Button ID="Button1" runat="server" Text="Clike me"
OnClick="Button1_Click" OnClientClick="aspnetForm.target ='_blank';"
Width="160px" CssClass="auto-style1" Height="32px" />
<br />
<br />
<asp:RadioButtonList ID="RadioButtonList1" runat="server">
<asp:ListItem>CNN</asp:ListItem>
<asp:ListItem>BBC</asp:ListItem>
<asp:ListItem>FOX</asp:ListItem>
</asp:RadioButtonList>
<br />
<br />
<textarea id="TextArea1" name="S1" runat="server" ></textarea></form>
</body>
</html>
and
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Drawing;
using System.Threading;
using System.Windows.Forms;
public partial class _Default : System.Web.UI.Page
{
Uri url = null;
WebBrowser wb = new WebBrowser();
protected void Button1_Click(object sender, EventArgs e)
{
wb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(DisplayText);
if (RadioButtonList1.Text == "CNN")
{
url = new Uri("http://www.edition.cnn.com/");
wb.Url = url;
//Response.Redirect(url);
}
else if (RadioButtonList1.Text == "BBC")
{
url = new Uri("http://www.bbc.com/");
wb.Url = url;
}
else
{
url = new Uri("http://www.foxnews.com/");
wb.Url = url;
}
}
private void DisplayText(object sender, WebBrowserDocumentCompletedEventArgs e)
{
WebBrowser wb = (WebBrowser)sender;
wb.Document.ExecCommand("SelectAll", false, null);
wb.Document.ExecCommand("Copy", false, null);
TextArea1.Value = Clipboard.GetText();
}
protected void Page_Load(object sender, EventArgs e)
{
}
}
but i have this error in line
WebBrowser wb = new WebBrowser();
ActiveX control '8856f961-340a-11d0-a96b-00c04fd705a2' cannot be instantiated because the current thread is not in a single-threaded apartment.
so what i'm doing wrong pleas help and many thanks in advance
3 answers
solution1
0 2014-06-08 18:36:15
I have never attempted to use WebBrowser in an object-reference, but I know that this being a web-Form means you will be receiving post backs, and if you re-instantiate the Browser reference each time, it isn't going to operate like the Page object. I would just use the Page object, you can collect any controls and methods needed, while also utilizing Request/Response namespaces. I would also match on the radiobuttonlist control like the code below:
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
string url;
RadioButtonList rdl = new RadioButtonList();
url = rdl.SelectedItem.Text;
}
}
Of course you'd just grab the .SelectedItem.Text from your markup-based RadioButtonList, instead of building one.
I checked, and it also seems like the WebBrowser object is under System.Windows.Forms . From my experience, you never want to use that Library in Web Forms (bad experiences with MsgBox ).
I'd refactor using the sample above and just
Response.Redirect(url);
Hope that helps!
solution2
0 2014-06-09 10:25:12
您可能要考虑使用基于其他自动化控件的方法，例如WatiN（ 使用Windows Forms WebBrowser来访问c＃asp.net ）或HTML Agility Pack（参见网站自动化的最佳方法？ ）之类的东西。
solution3
0 2014-06-09 10:45:12
You can use html agility pack . Here is a sample code, taken from here :
var root = doc.DocumentNode;
var sb = new StringBuilder();
foreach (var node in root.DescendantNodesAndSelf())
{
if (!node.HasChildNodes)
{
string text = node.InnerText;
if (!string.IsNullOrEmpty(text))
sb.AppendLine(text.Trim());
}
}
An example code to show how to download the web page, you can try the following code (taken from here ):
HtmlDocument doc = new HtmlDocument();
doc.Load("file.htm");
foreach(HtmlNode link in doc.DocumentElement.SelectNodes("//a[@href"])
{
HtmlAttribute att = link["href"];
att.Value = FixLink(att);
}
doc.Save("file.htm");
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