.net - BackgroundWorker 上的 IsBusy 属性何时更改？

Question

该BackgroundWorker组件有一个IsBusy标志。在执行时RunWorkerASync，此标志设置为 True。RunWorkerASync完成时或完成时它会更改为 FalseRunWorkerCompleted吗？

Answer 1

该标志将在结束后IsBusy立即设置为 false ，然后再执行。假设您想从另一个函数中检索 ' 操作的结果，如下所示：RunWorkerASyncRunWorkerCompletedBackgroundWorker

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