需要在Visual Basic中创建30秒的延迟

Question

如何在visual basic中创建30秒的延迟.我只是希望VB等待30秒才能进入下一行代码!!

Answer 1

我知道在VB6中实现这一目标的最佳方法是在循环中包含对WaitForSingleObject或其他类似Wait API函数的调用.这种方法的一个很好的例子是Sergey Merzlikin编写的MsgWaitObj函数(源文章):

Option Explicit
'********************************************
'*    (c) 1999-2000 Sergey Merzlikin        *
'********************************************

Private Const STATUS_TIMEOUT = &H102&
Private Const INFINITE = -1& ' Infinite interval
Private Const QS_KEY = &H1&
Private Const QS_MOUSEMOVE = &H2&
Private Const QS_MOUSEBUTTON = &H4&
Private Const QS_POSTMESSAGE = &H8&
Private Const QS_TIMER = &H10&
Private Const QS_PAINT = &H20&
Private Const QS_SENDMESSAGE = &H40&
Private Const QS_HOTKEY = &H80&
Private Const QS_ALLINPUT = (QS_SENDMESSAGE Or QS_PAINT _
        Or QS_TIMER Or QS_POSTMESSAGE Or QS_MOUSEBUTTON _
        Or QS_MOUSEMOVE Or QS_HOTKEY Or QS_KEY)
Private Declare Function MsgWaitForMultipleObjects Lib "user32" _
        (ByVal nCount As Long, pHandles As Long, _
        ByVal fWaitAll As Long, ByVal dwMilliseconds _
        As Long, ByVal dwWakeMask As Long) As Long
Private Declare Function GetTickCount Lib "kernel32" () As Long

' The MsgWaitObj function replaces Sleep, 
' WaitForSingleObject, WaitForMultipleObjects functions.
' Unlike these functions, it
' doesn't block thread messages processing.
' Using instead Sleep:
'     MsgWaitObj dwMilliseconds
' Using instead WaitForSingleObject:
'     retval = MsgWaitObj(dwMilliseconds, hObj, 1&)
' Using instead WaitForMultipleObjects:
'     retval = MsgWaitObj(dwMilliseconds, hObj(0&), n),
'     where n - wait objects quantity,
'     hObj() - their handles array.

Public Function MsgWaitObj(Interval As Long, _
            Optional hObj As Long = 0&, _
            Optional nObj As Long = 0&) As Long
Dim T As Long, T1 As Long
If Interval <> INFINITE Then
    T = GetTickCount()
    On Error Resume Next
    T = T + Interval
    ' Overflow prevention
    If Err <> 0& Then
        If T > 0& Then
            T = ((T + &H80000000) _
            + Interval) + &H80000000
        Else
            T = ((T - &H80000000) _
            + Interval) - &H80000000
        End If
    End If
    On Error GoTo 0
    ' T contains now absolute time of the end of interval
Else
    T1 = INFINITE
End If
Do
    If Interval <> INFINITE Then
        T1 = GetTickCount()
        On Error Resume Next
     T1 = T - T1
        ' Overflow prevention
        If Err <> 0& Then
            If T > 0& Then
                T1 = ((T + &H80000000) _
                - (T1 - &H80000000))
            Else
                T1 = ((T - &H80000000) _
                - (T1 + &H80000000))
            End If
        End If
        On Error GoTo 0
        ' T1 contains now the remaining interval part
        If IIf((T1 Xor Interval) > 0&, _
            T1 > Interval, T1 < 0&) Then
            ' Interval expired
            ' during DoEvents
            MsgWaitObj = STATUS_TIMEOUT
            Exit Function
        End If
    End If
    ' Wait for event, interval expiration
    ' or message appearance in thread queue
    MsgWaitObj = MsgWaitForMultipleObjects(nObj, _
            hObj, 0&, T1, QS_ALLINPUT)
    ' Let's message be processed
    DoEvents
    If MsgWaitObj <> nObj Then Exit Function
    ' It was message - continue to wait
Loop
End Function

Answer 2

请记住,@ sanderd的答案中的Sleep解决方案实际上会锁定应用程序.换句话说,所有UI片段都没有响应.

如果您的目标是简单地阻止控件移动到下一行,同时允许UI响应,则还有其他选择.

一种是以下列方式循环30秒:

' Module Level
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

' Inside a method
Dim dt as Date
dt = Now
Do While DateDiff("s", dt, now) < 30
    DoEvents
    Sleep 50   ' put your app to sleep in small increments
               ' to avoid having CPU go to 100%
Loop

这不是实现你想要的最优雅的方式,但它完成了工作.

Answer 3

System.Threading.Thread.Sleep(30*1000) （@Moox 我的错；））

请注意，在 UI 线程中调用此方法将挂起整个应用程序，同时等待 30 秒。更好的选择是为您想要执行的代码生成一个新线程。

编辑：
由于您的其他问题是关于 VB6 的，这里有一个提供 VB6 Sleep 方法的链接：
http://www.freevbcode.com/ShowCode.Asp ?ID=7556