我可以等待一个网页浏览器来完成导航，使用for循环？ [英] Can I wait for a webbrowser to finish navigating, using a for loop?

问题描述

我有一个循环：

for (i = 0; i <= 21; i++)
{
  webB.Navigate(URL);
}

韦伯是一个WebBrowser控件和 I 是一个int。

webB is a webBrowser control and i is an int.

我要等待浏览器来完成导航。

I want to wait for the browser to finish navigating.

我发现<一个href=\"http://stackoverflow.com/questions/583897/c-sharp-how-to-wait-for-a-webpage-to-finish-loading-before-continuing\">this,但是：

• 我不希望使用任何API或加载项


• 我无法用另一个无效的功能，如这个答案建议

• I don't want to use any APIs or addins
• I can't use another void function, as suggested in this answer

有没有办法等待，而在for循环？

Is there a way to wait while in a for loop?

推荐答案

假设你的主机 web浏览器在WinFroms应用程序，你可以做到在一个循环方便，高效地，使用异步/的await 模式。试试这个：

Assuming you host WebBrowser in a WinFroms application, you can do it in a loop easily and efficiently, using async/await pattern. Try this:

async Task DoNavigationAsync()
{
    TaskCompletionSource<bool> tcsNavigation = null;
    TaskCompletionSource<bool> tcsDocument = null;

    this.WB.Navigated += (s, e) =>
    {
        if (tcsNavigation.Task.IsCompleted)
            return;
        tcsNavigation.SetResult(true);
    };

    this.WB.DocumentCompleted += (s, e) =>
    {
        if (this.WB.ReadyState != WebBrowserReadyState.Complete)
            return;
        if (tcsDocument.Task.IsCompleted)
            return;
        tcsDocument.SetResult(true); 
    };

    for (var i = 0; i <= 21; i++)
    {
        tcsNavigation = new TaskCompletionSource<bool>();
        tcsDocument = new TaskCompletionSource<bool>();

        this.WB.Navigate("http://www.example.com?i=" + i.ToString());
        await tcsNavigation.Task;
        Debug.Print("Navigated: {0}", this.WB.Document.Url);
        // navigation completed, but the document may still be loading

        await tcsDocument.Task;
        Debug.Print("Loaded: {0}", this.WB.DocumentText);
        // the document has been fully loaded, you can access DOM here
    }
}

现在，是要明白， DoNavigationAsync 异步执行是非常重要的。下面是你从的Form_Load 调用它，处理它的完成：

Now, it's important to understand that DoNavigationAsync executes asynchronously. Here's how you'd call it from Form_Load and handle the completion of it:

void Form_Load(object sender, EventArgs e)
{
    var task = DoNavigationAsync();
    task.ContinueWith((t) =>
    {
        MessageBox.Show("Navigation done!");
    }, TaskScheduler.FromCurrentSynchronizationContext());
}

我已经回答过类似的问题<一href=\"http://stackoverflow.com/questions/18280487/flow-of-webbrowser-navigate-and-invokescript/18283479\">here.

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