The best you can do is to handle the LocationChanged event and get the URL. You can then revert back to the previous URL.
Well, I was able to detect the page following your guidance.
My first idea was to send the page to the browser to print (fx.ShowExternalDocument), but there needs to be an open session, so the browser asks for a username and password.
The webview correctly renders what needs to be printed.
So I tried to print the content using JavaFX8 (I printed the webview), but the result was terrible.
Would it be possible to capture the rendered html in the webview and then use the printhtml to print?