网络浏览器行为问题
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【中文标题】网络浏览器行为问题【英文标题】:Webbrowser behaviour issues 【发布时间】:2013-09-05 12:40:46 【问题描述】:我正在尝试使用 .NET C# 自动化 Web 浏览器。问题是控件或者我应该说 IE 浏览器在不同的计算机上表现得很奇怪。例如,我在第一台计算机上单击链接并填写 Ajax 弹出表单,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,上面的代码不能在第二台电脑上运行,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,我必须调用两个加载完成链。有人可以建议我应该如何处理这个问题吗?此外,提出更稳健的方法的建议将非常有帮助。提前谢谢你
【问题讨论】:
【参考方案1】:我可以推荐两件事:
不要在DocumentComplete
事件上执行您的代码,而是在 DOM window.onload 事件上执行。
为确保您的网页在 WebBrowser
控件中的行为与在完整 Internet Explorer 浏览器中的行为方式相同,请考虑实现 Feature Control。
[EDITED] 根据您的代码结构,还有一个建议。显然,您执行了一系列导航/处理DocumentComplete
操作。为此,使用async/await
可能更自然、更容易。这是一个这样做的例子,有或没有async/await
。它也说明了如何处理onload
:
async Task DoNavigationAsync()
bool documentComplete = false;
TaskCompletionSource<bool> 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<bool>();
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<bool>(); // 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;
这是相同的代码没有async/await
模式(对于.NET 4.0):
Task DoNavigationAsync()
// save the correct continuation context for Task.ContinueWith
var continueContext = TaskScheduler.FromCurrentSynchronizationContext();
bool documentComplete = false;
TaskCompletionSource<bool> 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<bool>();
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<bool>(); // 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,它仍然是一段异步代码,它返回一个Task 对象。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());
在这里使用TAP pattern 的好处是DoNavigationAsync
是一个自包含的、独立的方法。它可以重复使用,并且不会干扰父对象(在本例中为主窗体)的状态。
【讨论】:
实际上,我已经实现了功能控制,因为这是我的问题:),我不确定 DOM onload 事件,因为我需要完成网页事件的下载才能实现点击?还是? 哦.. 我应该检查一下,我确实觉得我之前和@Jim 说过话 :] 随意尝试我链接的code,onload
确实在页面有时被解雇了满载(包括任何帧)。这种方法是一种更可靠的方法,可以确保页面已完成自己对onload
或onreadystatechange
DOM 事件的处理。
您可以解释一下,因为您注册了 DocumentCompleted 事件并在其中附加了 AttachEventHandler
你说得对,我执行了一系列 DocumentComplete 操作。我正在开发 .net 4,所以不确定 async/await 是否可用。另外,奇怪的是,通过事件处理,我可以在一台电脑上工作,而不能在另一台电脑上工作。那么根据您的经验, async/await 会是更强大的解决方案吗?
功能控制对我有用。谢谢以上是关于网络浏览器行为问题的主要内容,如果未能解决你的问题,请参考以下文章
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