.net BackgroundWorker的IsBusy属性何时更改？

BackgroundWorker

组件有一个

IsBusy

标志。在执行

RunWorkerASync

时，此标志设置为True。当

RunWorkerASync

完成时，或者当

RunWorkerCompleted

完成时，

IsBusy

标志将在

RunWorkerCompleted

执行之前，在

RunWorkerCompleted

结束时设置为False。假设您想从另一个函数中检索

BackgroundWorker

操作的结果，如下所示：

Dim MyResult = "Not Set"

Sub Foo()

    DoSomeStuff()

    RunWorkerASync()

    'Wait for worker
    While Worker.IsBusy
        Wait()
    End While

    'Use result
    'This won't work because MyResult hasn't been
    'set yet by the RunWorkerCompleted handler
    'Will Print "Not Set", unless, by a timing quirk,
    'RunWorkerCompleted has enough time to execute
    'Before using its result.
    Print MyResult
End Sub

Sub RunWorkerASync()
    e.Result = "Result has been set"
End Sub

Sub RunWorkerCompleted()
    MyResult = e.Result 'Worker's output
End Sub

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“在RunWorkerCompleted执行之前”-这不是真的，请参阅：