System.Windows.Forms.WebBrowser等待页面完全加载完毕 [英] System.Windows.Forms.WebBrowser wait until page has been fully loaded
问题描述
我一直在尝试通过 wait 和 async 使用许多不同的解决方案.似乎没有任何作用.我无法找到实际上完全等到页面已完全加载的解决方案.所有代码都在等待一段时间，但要等到页面加载完毕后才能进行下一个处理.
I have been trying a lot of different solutions with wait and async. Nothing seems to work. I was not able to find solution that actually fully waits until page has been fully loaded. All codes are waiting some time but not until page has been loaded and I am getting an error on next process.
如何在页面上找到 Document.GetElementById("quickFind_text_0")元素之前将示例代码设置为等待模式?
How I can set for example code into wait mode until Document.GetElementById("quickFind_text_0") element has been found on page?
这是我的代码:
private void button7_Click(object sender, EventArgs e)
{
webBrowser1.Navigate("https://company.crm4.dynamics.com/main.aspx?app=d365default&pagetype=entitylist&etn=opportunity");
webBrowser1.Document.GetElementById("shell-container").Document.GetElementById("quickFind_text_0").SetAttribute("value", "Airbus");
webBrowser1.Document.GetElementById("shell-container").Document.GetElementById("quickFind_text_0").InnerText = "Airbus";
//Thread.Sleep(2000);
HtmlElement fbLink = webBrowser1.Document.GetElementById("shell-container").Document.GetElementById("mainContent").Document.GetElementById("quickFind_button_0"); ;
fbLink.InvokeMember("click");
}
P.S.我必须两次"执行此操作，否则无法正常工作:
P.S. I have to do this "twice" otherwise it is not working:
webBrowser1.Document.GetElementById("shell-container").Document.GetElementById("quickFind_text_0").SetAttribute("value", "Airbus");
webBrowser1.Document.GetElementById("shell-container").Document.GetElementById("quickFind_text_0").InnerText = "Airbus";
在VBA中，这有效:
While .Busy
DoEvents
Wend
While .ReadyState <> 4
DoEvents
Wend
是否可以在C#中执行相同的操作?
Is it possible to do the same in C#?
我的完整代码如下.由于某种原因，异步/等待无法正常工作.
My full code below. For some reason async/await does not work.
System.NullReferenceException HResult = 0x80004003消息=对象引用未设置为对象的实例.来源= v.0.0.01
StackTrace:位于v._0._0._01.Browser.d__7.MoveNext()在C:\ Users \ PC \ source \ repos \ v.0.0.01 \ v.0.0.01 \ Browser.cs:第69行
System.NullReferenceException HResult=0x80004003 Message=Object reference not set to an instance of an object. Source=v.0.0.01
StackTrace: at v._0._0._01.Browser.d__7.MoveNext() in C:\Users\PC\source\repos\v.0.0.01\v.0.0.01\Browser.cs:line 69
这是我的代码:
using System;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace v.0._0._01
{
public static class WebBrowserExtensions
{
public static Task<Uri> DocumentCompletedAsync(this WebBrowser wb)
{
var tcs = new TaskCompletionSource<Uri>();
WebBrowserDocumentCompletedEventHandler handler = null;
handler = (_, e) =>
{
wb.DocumentCompleted -= handler;
tcs.TrySetResult(e.Url);
};
wb.DocumentCompleted += handler;
return tcs.Task;
}
}
public partial class Browser : Form
{
public Browser()
{
InitializeComponent();
}
private async void button7_Click(object sender, EventArgs e)
{
webBrowser1.Navigate("https://company.crm4.dynamics.com/main.aspx?app=d365default&pagetype=entitylist&etn=opportunity");
await webBrowser1.DocumentCompletedAsync(); // async magic
HtmlElement fbLink = webBrowser1.Document.GetElementById("shell-container").Document.GetElementById("mainContent").Document.GetElementById("quickFind_button_0"); ;
fbLink.InvokeMember("click");
}
}
}
这是源代码:
现在我也注意到 quickFind_text_0 和 quickFind_button_0 总是以相同的词开头，但数字却像 quickFind_text_1 和 quickFind_button_1 或 quickFind_text_2 和 quickFind_button_2 .但是，通过手动单击，所有内容都可以使用 quickFind_text_0 和 quickFind_button_0 .
Also now I have noticed that quickFind_text_0 and quickFind_button_0 always starts with same words but numbers are changing like quickFind_text_1 and quickFind_button_1 or quickFind_text_2 and quickFind_button_2. However by manual clicking everything works with quickFind_text_0 and quickFind_button_0.
推荐答案
以下是扩展方法，可轻松等待 DocumentCompleted 事件:
Here is an extension method for easy awaiting of the DocumentCompleted event:
public static class WebBrowserExtensions
{
public static Task<Uri> DocumentCompletedAsync(this WebBrowser wb)
{
var tcs = new TaskCompletionSource<Uri>();
WebBrowserDocumentCompletedEventHandler handler = null;
handler = (_, e) =>
{
wb.DocumentCompleted -= handler;
tcs.TrySetResult(e.Url);
};
wb.DocumentCompleted += handler;
return tcs.Task;
}
}
它可以这样使用:
private async void button1_Click(object sender, EventArgs e)
{
webBrowser1.Navigate("https://company.crm4.dynamics.com/main.aspx");
await webBrowser1.DocumentCompletedAsync(); // async magic
HtmlElement fbLink = webBrowser1.Document.GetElementById("quickFind_button_0");
fbLink.InvokeMember("click");
}
await 之后的行将在页面加载完成后运行.
The lines after the await will run after the page has completed loading.
更新:这是等待特定元素显示在页面中的另一种扩展方法:
Update: Here is another extension method for awaiting a specific element to appear in the page:
public static async Task<HtmlElement> WaitForElementAsync(this WebBrowser wb,
string elementId, int timeout = 30000, int interval = 500)
{
var stopwatch = Stopwatch.StartNew();
while (true)
{
try
{
var element = wb.Document.GetElementById(elementId);
if (element != null) return element;
}
catch { }
if (stopwatch.ElapsedMilliseconds > timeout) throw new TimeoutException();
await Task.Delay(interval);
}
}
例如，在调用使用XMLHttpRequest修改页面的click事件后，可以使用它:
It can be used for example after invoking a click event that modifies the page using XMLHttpRequest:
someButton.InvokeMember("click");
var mainContentElement = await webBrowser1.WaitForElementAsync("mainContent", 5000);
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