Question

我在Visual Basic中需要一个适合我的等待命令。

我知道：

Declare Sub Sleep Lib "kernel32.dll" (ByVal milliseconds As Long)
sleep 5000

但这会使程序无法响应。

System.Threading.Thread.Sleep(5000) 'The window doesn't load until the timing is over (useless)

我的代码：

Imports Microsoft.Win32 'To check if is 64Bit or 32Bit

Public Class Loading
  Private Sub Loading_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    If Registry.LocalMachine.OpenSubKey("Hardware\Description\System\CentralProcessor\0").GetValue("Identifier").ToString.Contains("x86") Then
      My.Settings.Is64 = False
    Else
      My.Settings.Is64 = True
    End If

    'I need command here

    If My.Settings.Is64 = True Then
      Form64.Show()
      Me.Close()
    Else
      MsgBox("No version developed for 32-bit computers.")
      End
    End If
  End Sub
End Class

错误：

@Idle_Mind

1. function 'OnInitialize' cannot be declared 'Overrides' because it does not override a function in a base class.
2.  'MinimumSplashScreenDisplayTime' is not a member of 'App.Loading.MyApplication'.
    3.  'OnInitialize' is not a member of 'Object'.

Answer 1

您是否尝试实施启动画面？ - ＆GT; @ChrisDunaway是的，我正在做一个闪屏。

进入“项目属性”并将主窗体保留为“启动”窗体。将启动画面窗体设置为底部的启动画面条目。现在单击右侧的“查看应用程序事件”按钮并覆盖OnIntialize，以便您可以像这样设置MinimumSplashScreenDisplayTime（）：

Namespace My

    ' The following events are available for MyApplication:
    ' 
    ' Startup: Raised when the application starts, before the startup form is created.
    ' Shutdown: Raised after all application forms are closed.  This event is not raised if the application terminates abnormally.
    ' UnhandledException: Raised if the application encounters an unhandled exception.
    ' StartupNextInstance: Raised when launching a single-instance application and the application is already active. 
    ' NetworkAvailabilityChanged: Raised when the network connection is connected or disconnected.
    Partial Friend Class MyApplication

        Protected Overrides Function OnInitialize(ByVal commandLineArgs As System.Collections.ObjectModel.ReadOnlyCollection(Of String)) As Boolean
            ' Set the display time to 5000 milliseconds (5 seconds). 
            Me.MinimumSplashScreenDisplayTime = 5000
            Return MyBase.OnInitialize(commandLineArgs)
        End Function

    End Class


End Namespace

有关详细信息，请参阅here。

Answer 2

如果你想在5秒后执行剩下的代码，为什么不创建一个单独的线程/任务，它将等待5秒，然后通过回调到主线程来触发其余的代码运行？这种方法不会挂起你的用户界面。

编辑：如果您需要启动画面，请删除Timer控件，将间隔设置为5秒，然后在Tick事件处理程序中运行其余代码。

假设您已经设置了Timer，请将加载代码移到Timer1_Tick处理程序：

Public Class Loading
  Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick
    'part 1
    If Registry.LocalMachine.OpenSubKey("Hardware\Description\System\CentralProcessor\0").GetValue("Identifier").ToString.Contains("x86") Then
      My.Settings.Is64 = False
    Else
      My.Settings.Is64 = True
    End If

    'part 2
    If My.Settings.Is64 = True Then
      Form64.Show()
      Me.Close()
    Else
      MsgBox("No version developed for 32-bit computers.")
      End
    End If
  End Sub
End Class

或者将第1部分保留在Load中，并将第2部分移至Tick。我更喜欢这个选项用于语义。

另外，不要忘记设置Timer.Enabled = True。

Answer 3

如果您想要一个地方取消该应用程序，您可以使用Application.Startup事件并在其中设置e.Cancel = True。完成后，主表格甚至不会出现;应用程序将退出。这可能看起来像：

Namespace My

    ' The following events are available for MyApplication:
    ' 
    ' Startup: Raised when the application starts, before the startup form is created.
    ' Shutdown: Raised after all application forms are closed.  This event is not raised if the application terminates abnormally.
    ' UnhandledException: Raised if the application encounters an unhandled exception.
    ' StartupNextInstance: Raised when launching a single-instance application and the application is already active. 
    ' NetworkAvailabilityChanged: Raised when the network connection is connected or disconnected.
    Partial Friend Class MyApplication

        Private Sub MyApplication_Startup(sender As Object, e As Microsoft.VisualBasic.ApplicationServices.StartupEventArgs) Handles Me.Startup
            If someCondition Then
                MessageBox.Show("oops")
                e.Cancel = True ' <-- main form will NOT show, app will simply exit
            End If
        End Sub

    End Class


End Namespace

Answer 4

这样做：

    For i As Integer = 1 To 500
        System.Threading.Thread.Sleep(10)
        System.Windows.Forms.Application.DoEvents()
    Next

编辑：小心DoEvents;如果用户点击某些内容或在不应该处理某个事件时，它可能会导致问题。见http://www.codinghorror.com/blog/2004/12/is-doevents-evil.html

Answer 5

由于睡眠和忙碌等待通常不受欢迎，您可以使用AutoResetEvent执行某些操作：

Private ReadOnly _resetEvent As AutoResetEvent = New AutoResetEvent(False)

Sub Pause(ByVal milliseconds As Long)
    Dim waitInterval As TimeSpan = TimeSpan.FromMilliseconds(milliseconds)
    While Not _resetEvent.WaitOne(waitInterval)
         ' Waiting!
    End While
End Sub

不建议这样做，但这是使用System.Diagnostics.Stopwatch类的示例：

Sub Pause(ByVal milliseconds As Long)
    If milliseconds <= 0 Then Return
    Dim sw As New Stopwatch()
    sw.Start()
    Dim i As Long = 0
    Do
        If i Mod 50000 = 0 Then ' Check the timer every 50,000th iteration
            sw.Stop()
            If sw.ElapsedMilliseconds >= milliseconds Then
                Exit Do
            Else
                sw.Start()
            End If
        End If
        i += 1
    Loop
End Sub

然后您需要暂停，只需调用此Pause()方法：

Pause(5000) ' Pause for 5 seconds

Visual Basic的基本延迟命令

5 个答案: