VB.NET WinForms - 如何从BackgroundWorker的线程访问主线程的对象？
我正在使用 BackgroundWorker，我希望 BackgroundWorker 执行从数据库中检索数据的过程，同时用户仍然可以在表单上执行其他任务。问题是，检索数据后，我似乎无法从 BackgroundWorker 的 DoWork 事件访问我的 Form 中的 ListView，我将使用我检索到的数据填充该 ListView。我应该怎么办？我错过了什么吗？
考虑这个例子，我就是这样做的：
Public Class Test
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Label1.Text = "Hello World"
End Sub
End Class
I'm working with BackgroundWorker, I want the BackgroundWorker do the retrieval process of data from database while the user can still do another task on the form. The problem is, after retrieving the data, I can't seem to access the ListView in my Form from the DoWork event of BackgroundWorker, I will populate that ListView using the data I've retrieved. What should I do? Am I missing something?
Consider this example, this is how I'm doing it:
Public Class Test
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Label1.Text = "Hello World"
End Sub
End Class
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BackgroundWorker 的文档非常清楚：
示例“如何：在后台下载文件” 显示了一个可以在主线程和后台工作人员之间共享对象的示例方式 - 通过安排将此类对象存储在类级别的变量中。
The documentation for BackgroundWorker is quite clear:
The sample "How to: Download a File in the Background" shows one example way that objects can be shared between the main thread and the background worker - by arranging for such objects to be stored in variables at the class level.
DoWorkEventArgs包含一个Argument属性，您可以在其中存储任何对象，例如包含用于操作 UI 的指令的用户定义的类。DoWorkEventArgscontains anArgumentproperty in which you can store any object, such as a user-defined class containing instructions for manipulating the UI.