在SystemEvents类中 可以 用户试图注销或关闭系统时发生。 (当用户试图注销或关闭系统时发生。当用户试图注销或关闭系统时发生。) 这个 事件处理函数中 可以找到如下方法
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Private Shared WM_QUERYENDSESSION As Integer = H11
Private Shared systemShutdown As Boolean = False
Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
If m.Msg = WM_QUERYENDSESSION Then
'MessageBox.Show("queryendsession: this is a logoff, shutdown, or reboot")
systemShutdown = True
End If
' If this is WM_QUERYENDSESSION, the closing event should be raised in the base WndProc.
MyBase.WndProc(m)
End Sub 'WndProc
Private Sub Form1_Closing(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
If (systemShutdown) Then
' Reset the variable because the user might cancel the shutdown.
systemShutdown = False
If (System.Windows.Forms.DialogResult.Yes = _
MessageBox.Show("My application", "Do you want to save your work before logging off?", MessageBoxButtons.YesNo)) Then
e.Cancel = True
Else
e.Cancel = False
End If
End If
End Sub
绑定窗体的FormClosing事件，执行e.Cancel = True即可。
如果你不想在任务栏上显示窗体，把窗体的ShowOnTaskbar设为False。
用
t.Suspend() 这个是挂起线程。是一个异步方法。
t.Sleep 我看了是一个同步方法。要等这个方法运行完了才继续下一步。
这和from.show和 from.showdiaglog区别差不多！
至于疑问2我也没找到原因。
VB.NET中实现"关机/休眠/重启/注销"的类Imports System
Imports System.Text
Imports System.Diagnostics
Imports System.Runtime.InteropServices
Public Class WindowsController
Public Enum RestartOptions
LogOff = 0
PowerOff = 8
Reboot = 2
ShutDown = 1
Suspend = -1
Hibernate = -2
End Enum
Public Structure LUID
Dim LowPart As Integer
Dim HighPart As Integer
End Structure
Public Structure LUID_AND_ATTRIBUTES
Dim pLuid As LUID
Dim Attributes As Integer
End Structure
Public Structure TOKEN_PRIVILEGES
Dim PrivilegeCount As Integer
Dim Privileges As LUID_AND_ATTRIBUTES
End Structure
Private Const TOKEN_ADJUST_PRIVILEGES = H20
Private Const TOKEN_QUERY = H8
Private Const SE_PRIVILEGE_ENABLED = H2
Private Const FORMAT_MESSAGE_FROM_SYSTEM = H1000
Private Const EWX_FORCE = 4
Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As IntPtr
Declare Function FreeLibrary Lib "kernel32" (ByVal hLibModule As IntPtr) As Integer
Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As IntPtr, ByVal lpProcName As String) As IntPtr
Declare Function SetSuspendState Lib "Powrprof" (ByVal Hibernate As Integer, ByVal ForceCritical As Integer, ByVal DisableWakeEvent As Integer) As Integer
Declare Function OpenProcessToken Lib "advapi32.dll" (ByVal ProcessHandle As IntPtr, ByVal DesiredAccess As Integer, ByRef TokenHandle As IntPtr) As Integer
Declare Function LookupPrivilegeValue Lib "advapi32.dll" Alias "LookupPrivilegeValueA" (ByVal lpSystemName As String, ByVal lpName As String, ByRef lpLuid As LUID) As Integer
Declare Function AdjustTokenPrivileges Lib "advapi32.dll" (ByVal TokenHandle As IntPtr, ByVal DisableAllPrivileges As Integer, ByRef NewState As TOKEN_PRIVILEGES, ByVal BufferLength As Integer, ByRef PreviousState As TOKEN_PRIVILEGES, ByRef ReturnLength As Integer) As Integer
Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Integer, ByVal dwReserved As Integer) As Integer
Declare Function FormatMessage Lib "kernel32" Alias "FormatMessageA" (ByVal dwFlags As Integer, ByVal lpSource As IntPtr, ByVal dwMessageId As Integer, ByVal dwLanguageId As Integer, ByVal lpBuffer As StringBuilder, ByVal nSize As Integer, ByVal Arguments As Integer) As Integer
Public Sub ExitWindows(ByVal how As RestartOptions, ByVal force As Boolean)
Select Case how
Case RestartOptions.Suspend
SuspendSystem(False, force)
Case RestartOptions.Hibernate
SuspendSystem(True, force)
Case Else
ExitWindows(Convert.ToInt32(how), force)
End Select
End Sub
Protected Sub ExitWindows(ByVal how As Integer, ByVal force As Boolean)
EnableToken("SeShutdownPrivilege")
If force Then how = how Or EWX_FORCE
If (ExitWindowsEx(how, 0) = 0) Then Throw New PrivilegeException(FormatError(Marshal.GetLastWin32Error()))
End Sub
Protected Sub EnableToken(ByVal privilege As String)
If Not CheckEntryPoint("advapi32.dll", "AdjustTokenPrivileges") Then Return
Dim tokenHandle As IntPtr = IntPtr.Zero
Dim privilegeLUID = New LUID()
Dim newPrivileges = New TOKEN_PRIVILEGES()
Dim tokenPrivileges As TOKEN_PRIVILEGES
If (OpenProcessToken(Process.GetCurrentProcess().Handle, TOKEN_ADJUST_PRIVILEGES Or TOKEN_QUERY, tokenHandle)) = 0 Then Throw New PrivilegeException(FormatError(Marshal.GetLastWin32Error()))
If (LookupPrivilegeValue("", privilege, privilegeLUID)) = 0 Then Throw New PrivilegeException(FormatError(Marshal.GetLastWin32Error()))
tokenPrivileges.PrivilegeCount = 1
tokenPrivileges.Privileges.Attributes = SE_PRIVILEGE_ENABLED
tokenPrivileges.Privileges.pLuid = privilegeLUID
Dim Size As Integer = 4
If (AdjustTokenPrivileges(tokenHandle, 0, tokenPrivileges, 4 + (12 * tokenPrivileges.PrivilegeCount), newPrivileges, Size)) = 0 Then Throw New PrivilegeException(FormatError(Marshal.GetLastWin32Error()))
End Sub
Protected Sub SuspendSystem(ByVal hibernate As Boolean, ByVal force As Boolean)
If Not CheckEntryPoint("powrprof.dll", "SetSuspendState") Then Throw New PlatformNotSupportedException("The SetSuspendState method is not supported on this system!")
SetSuspendState(Convert.ToInt32(IIf(hibernate, 1, 0)), Convert.ToInt32(IIf(force, 1, 0)), 0)
End Sub
Protected Function CheckEntryPoint(ByVal library As String, ByVal method As String) As Boolean
Dim libPtr As IntPtr = LoadLibrary(library)
If Not libPtr.Equals(IntPtr.Zero) Then
If Not GetProcAddress(libPtr, method).Equals(IntPtr.Zero) Then
FreeLibrary(libPtr)
Return True
End If
FreeLibrary(libPtr)
End If
Return False
End Function
Protected Function FormatError(ByVal number As Integer) As String
Dim Buffer = New StringBuilder(255)
FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, IntPtr.Zero, number, 0, Buffer, Buffer.Capacity, 0)
Return Buffer.ToString()
End Function
End Class
Public Class PrivilegeException
Inherits Exception
Public Sub New()
MyBase.New()
End Sub
Public Sub New(ByVal message As String)
MyBase.New(message)
End Sub
End Class
例如实现注销功能：
Dim shutdown As New WindowsController()
shutdown.ExitWindows(shutdown.RestartOptions.LogOff, False
它在System.Threading命名空间的Thread类中定义了
直接用 System.Threading.Thread.Sleep()方法
System.Threading.Thread.Sleep(time )‘time为整数，单位毫秒
设定Timer象间触发事件再给handler发消息处理行处理完重置timer间进入循环即随便用wait类土办容易系统判定进程挂死kill