c# - 如何使用 WebBrowser 获取新窗口的 URL

Question

我想抓取一个网页。问题是，这个网页有一个只能点击的加密链接。使用 webBrowser.Navigate 不起作用。我设法模拟了一个点击 Action ，它打开了一个新窗口。现在我想要的是获取新窗口的 url。

private void Form1_Load(object sender, EventArgs e)
    {
        webBrowser1.Navigate(@"http://www.downarchive.ws/software/downloaders/795011-easy-mp3-downloader-4536.html");
    }

    private void webBrowser1_Navigated(object sender, WebBrowserNavigatedEventArgs e)
    {
        HtmlElementCollection links = webBrowser1.Document.GetElementsByTagName("a");

        foreach (HtmlElement link in links)
        {
            if (link.GetAttribute("href").Contains(@"http://www.downarchive.ws/engine/go.php?url="))
            {
                link.InvokeMember("Click");
                break;
            }
        }
    }

    private void webBrowser1_NewWindow(object sender, CancelEventArgs e)
    {
        var webBrowser = (WebBrowser)sender;
        MessageBox.Show(webBrowser.Url.ToString());

    }

Answer 1

1) 您不需要调用点击。最好使用 Navigate 方法。当您调用点击时，链接可能会在新窗口中打开，可能会执行一些额外的 javascript 等。

2)如果需要在所有重定向后获取url，有DocumentCompleted事件:

WebBrowserDocumentCompletedEventHandler onDocumentCompleted = (sender, e) => {
    Uri theUlrThatYouNeed = e.Url;
    webBrowser1.DocumentCompleted -= onDocumentCompleted;
};
webBrowser1.DocumentCompleted += onDocumentCompleted;
webBrowser1.Navigate("your encrypted url");

3) 如果链接是在外部 IE 窗口中打开的，那么它对您来说已经消失了 - 您无法控制外部浏览器并从中接收事件。有时，重定向可以打开新窗口。为防止这种情况，您可以使用扩展的 WebBrowser 类:

namespace ExtendedWebBrowser {
[ComImport, TypeLibType(TypeLibTypeFlags.FHidden),
InterfaceType(ComInterfaceType.InterfaceIsIDispatch),
Guid("34A715A0-6587-11D0-924A-0020AFC7AC4D")]
public interface DWebBrowserEvents2 {
    /// <summary>
    /// 
    /// </summary>
    /// <param name="ppDisp">
    /// An interface pointer that, optionally, receives the IDispatch interface
    /// pointer of a new WebBrowser object or an InternetExplorer object.
    /// </param>
    /// <param name="Cancel">
    /// value that determines whether the current navigation should be canceled
    /// </param>
    /// <param name="dwFlags">
    /// The flags from the NWMF enumeration that pertain to the new window
    /// See http://msdn.microsoft.com/en-us/library/bb762518(VS.85).aspx.
    /// </param>
    /// <param name="bstrUrlContext">
    /// The URL of the page that is opening the new window.
    /// </param>
    /// <param name="bstrUrl">The URL that is opened in the new window.</param>
    [DispId(0x111)]
    void NewWindow3(
        [In, Out, MarshalAs(UnmanagedType.IDispatch)] ref object ppDisp,
        [In, Out] ref bool Cancel,
        [In] uint dwFlags,
        [In, MarshalAs(UnmanagedType.BStr)] string bstrUrlContext,
        [In, MarshalAs(UnmanagedType.BStr)] string bstrUrl);
}
public partial class WebBrowserEx : WebBrowser {
    AxHost.ConnectionPointCookie cookie;
    DWebBrowserEvent2Helper helper;
    [Browsable(true)]
    public event EventHandler<WebBrowserNewWindowEventArgs> NewWindow3;
    [PermissionSetAttribute(SecurityAction.LinkDemand, Name = "FullTrust")]
    public WebBrowserEx() {
    }
    /// <summary>
    /// Associates the underlying ActiveX control with a client that can 
    /// handle control events including NewWindow3 event.
    /// </summary>
    [PermissionSetAttribute(SecurityAction.LinkDemand, Name = "FullTrust")]
    protected override void CreateSink() {
        base.CreateSink();

        helper = new DWebBrowserEvent2Helper(this);
        cookie = new AxHost.ConnectionPointCookie(
            this.ActiveXInstance, helper, typeof(DWebBrowserEvents2));
    }
    /// <summary>
    /// Releases the event-handling client attached in the CreateSink method
    /// from the underlying ActiveX control
    /// </summary>
    [PermissionSetAttribute(SecurityAction.LinkDemand, Name = "FullTrust")]
    protected override void DetachSink() {
        if (cookie != null) {
            cookie.Disconnect();
            cookie = null;
        }
        base.DetachSink();
    }
    /// <summary>
    ///  Raises the NewWindow3 event.
    /// </summary>
    protected virtual void OnNewWindow3(WebBrowserNewWindowEventArgs e) {
        if (this.NewWindow3 != null) {
            this.NewWindow3(this, e);
        }
    }
    private class DWebBrowserEvent2Helper : StandardOleMarshalObject, DWebBrowserEvents2 {
        private WebBrowserEx parent;
        public DWebBrowserEvent2Helper(WebBrowserEx parent) {
            this.parent = parent;
        }
        /// <summary>
        /// Raise the NewWindow3 event.
        /// If an instance of WebBrowser2EventHelper is associated with the underlying
        /// ActiveX control, this method will be called When the NewWindow3 event was
        /// fired in the ActiveX control.
        /// </summary>
        public void NewWindow3(ref object ppDisp, ref bool Cancel, uint dwFlags,
            string bstrUrlContext, string bstrUrl) {
            var e = new WebBrowserNewWindowEventArgs(bstrUrl, Cancel);
            this.parent.OnNewWindow3(e);
            Cancel = e.Cancel;
        }
    }
}
public class WebBrowserNewWindowEventArgs : EventArgs {
    public String Url { get; set; }
    public Boolean Cancel { get; set; }
    public WebBrowserNewWindowEventArgs(String url, Boolean cancel) {
        this.Url = url;
        this.Cancel = cancel;
    }
}
}

void WebBrowser_NewWindow(object sender, WebBrowserNewWindowEventArgs e) {
  if (!string.IsNullOrEmpty(e.Url)) {

    //Prevent new window
    e.Cancel = true;

    // Navigate to url from new window
    Navigate(e.Url);
  }
}

因此，如果您在其改进版本上替换 WebBrowser 控件，您将能够阻止新窗口。