Web浏览器行为问题

我试图用.NET C＃自动化Webbrowser。 问题是控件或我应该说IE浏览器在不同的计算机上表现得很奇怪。 例如，我点击链接并在第一台计算机上填充Ajax弹出窗体，如下所示，没有任何错误：

private void btn_Start_Click(object sender, RoutedEventArgs e) { webbrowserIE.Navigate("http://www.test.com/"); webbrowserIE.DocumentCompleted += fillup_LoadCompleted; } void fillup_LoadCompleted(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e) { System.Windows.Forms.HtmlElement ele = web_BrowserIE.Document.GetElementById("login"); if (ele != null) ele.InvokeMember("Click"); if (this.web_BrowserIE.ReadyState == System.Windows.Forms.WebBrowserReadyState.Complete) { web_BrowserIE.Document.GetElementById("login").SetAttribute("value", myUserName); web_BrowserIE.Document.GetElementById("password").SetAttribute("value", myPassword); foreach (System.Windows.Forms.HtmlElement el in web_BrowserIE.Document.GetElementsByTagName("button")) { if (el.InnerText == "Login") { el.InvokeMember("click"); } } web_BrowserIE.DocumentCompleted -= fillup_LoadCompleted; } } 

但是，上面的代码不适用于第二台PC，唯一的点击方式是这样的：

 private void btn_Start_Click(object sender, RoutedEventArgs e) { webbrowserIE.DocumentCompleted += click_LoadCompleted; webbrowserIE.Navigate("http://www.test.com/"); } void click_LoadCompleted(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e) { if (this.webbrowserIE.ReadyState == System.Windows.Forms.WebBrowserReadyState.Complete) { System.Windows.Forms.HtmlElement ele = webbrowserIE.Document.GetElementById("login"); if (ele != null) ele.InvokeMember("Click"); webbrowserIE.DocumentCompleted -= click_LoadCompleted; webbrowserIE.DocumentCompleted += fillup_LoadCompleted; } } void click_LoadCompleted(object sender, System.Windows.Forms.WebBrowserDocumentCompletedEventArgs e) { webbrowserIE.Document.GetElementById("login_login").SetAttribute("value", myUserName); webbrowserIE.Document.GetElementById("login_password").SetAttribute("value", myPassword); //If you know the ID of the form you would like to submit: foreach (System.Windows.Forms.HtmlElement el in webbrowserIE.Document.GetElementsByTagName("button")) { if (el.InnerText == "Login") { el.InvokeMember("click"); } } webbrowserIE.DocumentCompleted -= click_LoadCompleted; } 

因此，在第二个解决方案中，我必须调用两个Load Completed Chains。 有人可以建议我该如何处理这个问题？ 此外，提出更强大的方法将非常有帮助。 先感谢您

Answer 1

我可以推荐两件事：

• 不要在DocumentComplete事件上执行代码，而是在DOM window.onload事件上执行。
• 要确保您的Web页面在WebBrowser控件中的行为与在完整Internet Explorer浏览器中的行为相同，请考虑实现Feature Control 。

[已编辑]根据代码的结构，还有一个建议。 显然，您执行一系列导航/处理DocumentComplete操作。 它可能更自然，更容易使用async/await 。 以下是使用或不使用async/await执行此操作的示例。 它还说明了如何处理onload ：

 async Task DoNavigationAsync() { bool documentComplete = false; TaskCompletionSource onloadTcs = null; WebBrowserDocumentCompletedEventHandler handler = delegate { if (documentComplete) return; // attach to onload only once per each Document documentComplete = true; // now subscribe to DOM onload event this.wb.Document.Window.AttachEventHandler("onload", delegate { // each navigation has its own TaskCompletionSource if (onloadTcs.Task.IsCompleted) return; // this should not be happening // signal the completion of the page loading onloadTcs.SetResult(true); }); }; // register DocumentCompleted handler this.wb.DocumentCompleted += handler; // Navigate to http://www.example.com?i=1 documentComplete = false; onloadTcs = new TaskCompletionSource(); this.wb.Navigate("http://www.example.com?i=1"); await onloadTcs.Task; // the document has been fully loaded, you can access DOM here MessageBox.Show(this.wb.Document.Url.ToString()); // Navigate to http://example.com?i=2 // could do the click() simulation instead documentComplete = false; onloadTcs = new TaskCompletionSource(); // new task for new navigation this.wb.Navigate("http://example.com?i=2"); await onloadTcs.Task; // the document has been fully loaded, you can access DOM here MessageBox.Show(this.wb.Document.Url.ToString()); // no more navigation, de-register DocumentCompleted handler this.wb.DocumentCompleted -= handler; } 

这是没有async/await模式的相同代码（对于.NET 4.0）：

 Task DoNavigationAsync() { // save the correct continuation context for Task.ContinueWith var continueContext = TaskScheduler.FromCurrentSynchronizationContext(); bool documentComplete = false; TaskCompletionSource onloadTcs = null; WebBrowserDocumentCompletedEventHandler handler = delegate { if (documentComplete) return; // attach to onload only once per each Document documentComplete = true; // now subscribe to DOM onload event this.wb.Document.Window.AttachEventHandler("onload", delegate { // each navigation has its own TaskCompletionSource if (onloadTcs.Task.IsCompleted) return; // this should not be happening // signal the completion of the page loading onloadTcs.SetResult(true); }); }; // register DocumentCompleted handler this.wb.DocumentCompleted += handler; // Navigate to http://www.example.com?i=1 documentComplete = false; onloadTcs = new TaskCompletionSource(); this.wb.Navigate("http://www.example.com?i=1"); return onloadTcs.Task.ContinueWith(delegate { // the document has been fully loaded, you can access DOM here MessageBox.Show(this.wb.Document.Url.ToString()); // Navigate to http://example.com?i=2 // could do the 'click()' simulation instead documentComplete = false; onloadTcs = new TaskCompletionSource(); // new task for new navigation this.wb.Navigate("http://example.com?i=2"); onloadTcs.Task.ContinueWith(delegate { // the document has been fully loaded, you can access DOM here MessageBox.Show(this.wb.Document.Url.ToString()); // no more navigation, de-register DocumentCompleted handler this.wb.DocumentCompleted -= handler; }, continueContext); }, continueContext); } 

注意，在这两种情况下，它仍然是一段返回Task对象的异步代码。 以下是如何处理此类任务完成的示例：

 private void Form1_Load(object sender, EventArgs e) { DoNavigationAsync().ContinueWith(_ => { MessageBox.Show("Navigation complete!"); }, TaskScheduler.FromCurrentSynchronizationContext()); } 

这里使用TAP模式的好处是DoNavigationAsync是一种独立的独立方法。 它可以重用，并且不会干扰父对象的状态（在本例中是主窗体）。