This文章说：
如果应用程序必须阻止潜在的系统关闭，则可以调用 ShutdownBlockReasonCreate函数。来电者提供原因 将显示给用户的字符串。
在ShutdownBlockReasonCreate文档中，它明确指示尝试关闭时将向用户显示带有原因字符串的对话框窗口：
指示无法关闭系统并设置原因字符串 启动系统关机后向用户显示
在this讨论中确认了该对话框窗口的外观：
用户可以单击“仍然关闭”。此外，系统假设 如果用户在一定数量的时间内未采取任何措施，则“仍然关闭” 秒。
但是，在我调用 ShutdownBlockReasonCreate 并传递了当前应用程序的主窗口句柄之后，确保该函数成功，并通过调用ShutdownBlockReasonQuery函数以检索原因字符串来对其进行两次保证，不会阻止用户关闭系统，也不会显示对话框。
为什么它对我的系统没有影响？如何解决此问题？。
我正在使用管理员（内置）帐户在Windows 10 x64上运行，而我正在使用的代码来自this GitHub存储库：
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using Vanara.PInvoke;
using static Vanara.PInvoke.User32;
namespace Vanara.Windows.Forms.Forms
{
/// <summary>Used to define a set of operations within which any shutdown request will be met with a reason why this application is blocking it.</summary>
/// <remarks>This is to be used in either a 'using' statement or for the life of the application.
/// <para>To use for the life of the form, define a class field:
public class PreventShutdownContext : IDisposable
{
private HandleRef href;
/// <summary>Initializes a new instance of the <see cref="PreventShutdownContext"/> class.</summary>
/// <param name="window">The <see cref="Form"/> or <see cref="Control"/> that contains a valid window handle.</param>
/// <param name="reason">The reason the application must block system shutdown. Because users are typically in a hurry when shutting down the system, they may spend only a few seconds looking at the shutdown reasons that are displayed by the system. Therefore, it is important that your reason strings are short and clear.</param>
public PreventShutdownContext(Control window, string reason)
{
href = new HandleRef(window, window.Handle);
Reason = reason;
}
/// <summary>The reason the application must block system shutdown. Because users are typically in a hurry when shutting down the system, they may spend only a few seconds looking at the shutdown reasons that are displayed by the system. Therefore, it is important that your reason strings are short and clear.</summary>
/// <value>The reason string.</value>
public string Reason
{
get
{
if (!ShutdownBlockReasonQuery(href.Handle, out var reason))
Win32Error.ThrowLastError();
return reason;
}
set
{
if (value == null) value = string.Empty;
if (ShutdownBlockReasonQuery(href.Handle, out var _))
ShutdownBlockReasonDestroy(href.Handle);
if (!ShutdownBlockReasonCreate(href.Handle, value))
Win32Error.ThrowLastError();
}
}
/// <summary>Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.</summary>
public void Dispose()
{
ShutdownBlockReasonDestroy(href.Handle);
}
}
}
...
[DllImport(Lib.User32, SetLastError = true, ExactSpelling = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool ShutdownBlockReasonCreate(HWND hWnd, [MarshalAs(UnmanagedType.LPWStr)] string reason);
[DllImport(Lib.User32, SetLastError = true, ExactSpelling = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool ShutdownBlockReasonQuery(HWND hWnd, [MarshalAs(UnmanagedType.LPWStr)] StringBuilder pwszBuff, ref uint pcchBuff);
[DllImport(Lib.User32, SetLastError = true, ExactSpelling = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool ShutdownBlockReasonDestroy(HWND hWnd);
具有这样的用法：
using (new PreventShutdownContext(this, "This app is super busy right now."))
{
// Do something that can't be interrupted...
}
我尝试了使用P / Invoke定义的代码，并对代码进行了少许修改，在该代码上我将 IntPtr 结构用于窗口句柄，而不是自定义{{3 }}结构，并将其传递给应用程序的主窗口句柄，如我在上面的注释中指定的那样。
答案 0 :(得分：3)
这是设计使然。
documentation（以及您引用的主题）可能会引起误解。
表示无法关闭系统，并设置启动系统关闭后向用户显示的原因字符串。
如果应用程序必须阻止潜在的系统关闭，则可以调用
ShutdownBlockReasonCreate函数。
此功能实际上仅为您的应用设置消息字符串。此功能不会防止关闭您的应用程序。
要实现关闭模块，只需遵循您引用的文章中描述的步骤。您需要对WM_QUERYENDSESSION消息作出反应，并返回FALSE（0）。
作为参考，另请参阅WM_QUERYENDSESSION文档。
您可能还会发现有趣的this topic-它描述了Windows Vista引入的更改，并包含了如何实现关闭逻辑的最佳实践。
顺便说一句，关于您的应用程序将没有特殊的“对话窗口”。将显示标准的Windows关闭用户界面（视操作系统版本而有所不同）。您的应用程序将显示在“防止关机的应用程序” 列表中，其中包含您使用ShutdownBlockReasonCreate函数注册的消息-但仅当它返回{{1 }}消息。
如果上述解决方案（FALSE）无法解决问题，则可能是由忽略该机制的系统设置引起的。
@ElektroStudios在研究中发现：
WM_QUERYENDSESSION注册表值（可在WM_QUERYENDSESSION注册表项中找到），则关闭操作不会显示任何用户界面来让用户取消关闭操作。因此，在这种情况下创建“取消关闭原因”是没有用的，因为在任何情况下应用都将被迫立即关闭（以继续关闭）。作为参考，请阅读this MS Docs topic。AutoEndTasks注册表值必须为0（零）；必须为0。否则，任何试图阻止关机的应用都将终止，并且在关机时不会显示任何用户界面。 HKCU\Control Panel\Desktop值添加到AutoEndTasks键中，该键将覆盖AutoEndTasks配置单元和HKEY_USERS\.DEFAULT\Control Panel\Desktop中定义的值。这意味着，如果HKCU在HKU\{SID}中是AutoEndTasks（0）但在false中是HKCU（1），则应用程序将不会阻止系统关闭并不会显示关闭用户界面。如果true在HKU\.DEFAULT中是AutoEndTasks但在false中是true，则该应用将阻止系统关闭，并显示关闭UI。HKU\.DEFAULT值不需要重新启动/注销系统即可生效。因此，一旦在正确的密钥（例如HKCU）中将其设置为AutoEndTasks，应用程序将阻止系统关闭，当我们使用完该功能后，我们可以将该值恢复为以前的状态功能。答案 1 :(得分：0)
如果有人感兴趣，我将在VB.NET中共享我的自定义实现。当前，此代码缺少Windows API定义以及我用于读取/写入 AutoEndTasks 注册表值（以下代码中名称为TweakingUtil.AutoEndTasks的成员）的方法，但是你会得到我认为最重要的想法...
Imports Microsoft.Win32
Imports System.Security
''' ----------------------------------------------------------------------------------------------------
''' <summary>
''' Provides a mechanism to prevent any system shutdown/restart/log-off request during the life-cycle of a instance of this class.
''' <para></para>
''' Applications should use this class as they begin an operation that cannot be interrupted, such as burning a CD or DVD.
''' <para></para>
''' This class is to be used in either a <see langword="Using"/> statement or for the life-cycle of the current application.
''' </summary>
''' ----------------------------------------------------------------------------------------------------
''' <remarks>
''' Original source-code: <see href="https://github.com/dahall/Vanara/blob/master/WIndows.Forms/Contexts/PreventShutdownContext.cs"/>
''' </remarks>
''' ----------------------------------------------------------------------------------------------------
''' <example> This is a code example.
''' <code lang="vb">
''' Using psc As New PreventShutdownContext("Critical operation is in progress...")
''' ' Do something that can't be interrupted...
''' End Using
''' </code>
''' </example>
''' ----------------------------------------------------------------------------------------------------
''' <example> This is a code example.
''' <code lang="vb">
''' Public NotInheritable Class Form1 : Inherits Form
'''
''' Private psc As PreventShutdownContext
'''
''' Private Sub AllowShutdown()
''' If (Me.psc IsNot Nothing) Then
''' Me.psc.Dispose()
''' Me.psc = Nothing
''' End If
''' End Sub
'''
''' Private Sub DisallowShutdown()
''' If (Me.psc Is Nothing) Then
''' Me.psc = New PreventShutdownContext("Application defined reason goes here.")
''' End If
''' End Sub
'''
''' Protected Overrides Sub OnShown(ByVal e As EventArgs)
''' Me.DisallowShutdown()
''' MyBase.OnShown(e)
''' End Sub
'''
''' End Class
''' </code>
''' </example>
''' ----------------------------------------------------------------------------------------------------
''' <example> This is a code example using the <see langword="using"/> statement.
''' <code lang="cs">
''' using (new PreventShutdownContext("Critical operation is in progress...")) {
''' // Do something that can't be interrupted...
''' }
''' </code>
''' </example>
''' ----------------------------------------------------------------------------------------------------
''' <code lang="cs">
''' public partial class Form1 : Form {
'''
''' private PreventShutdownContext disallowShutdown;
'''
''' private void AllowShutdown() {
''' if (this.psc != null) {
''' this.psc.Dispose();
''' this.psc = null;
''' }
''' }
'''
''' private void DisallowShutdown() {
''' if (this.psc == null) {
''' this.psc = new PreventShutdownContext("Application defined reason goes here.");
''' }
''' }
'''
''' protected override void OnShown(EventArgs e) {
''' this.DisallowShutdown();
''' base.OnShown(e);
''' }
'''
''' }
''' </code>
''' ----------------------------------------------------------------------------------------------------
Public NotInheritable Class PreventShutdownContext : Implements IDisposable
#Region " Private Fields "
''' <summary>
''' Holds the main window handle for the current application.
''' </summary>
Private ReadOnly hRef As HandleRef
''' <summary>
''' Flag to determine whether the shutdown reason is created.
''' </summary>
Private isReasonCreated As Boolean
''' <summary>
''' Holds the previous value of "HKEY_USERS\.DEFAULT\Control Panel\Desktop" "AutoEndTasks" registry value.
''' <para></para>
''' This registry value is restored when calling <see cref="PreventShutdownContext.Dispose()"/>
''' </summary>
Private ReadOnly previousAutoEndTasksValue As Boolean
#End Region
#Region " Constructors "
''' <summary>
''' Initializes a new instance of the <see cref="PreventShutdownContext"/> class.
''' </summary>
''' <param name="reason">
''' The reason for which the current application must prevent system shutdown.
''' <para></para>
''' Because users are typically in a hurry when shutting down the system,
''' they may spend only a few seconds looking at the shutdown reasons that are displayed by the system.
''' Therefore, it is important that your reason strings are short and clear.
''' </param>
'''
''' <param name="throwOnError">
''' If <see langword="True"/>, an exception will be thrown if
''' the application does not meet the requirements to prevent a system shutdown.
''' <para></para>
''' Default value is <see langword="True"/>.
''' </param>
''' <exception cref="InvalidOperationException">
''' Applications without a user interface can't prevent a system shutdown.
''' </exception>
'''
''' <exception cref="InvalidOperationException">
''' The main window of the current application is not yet created or is not visible.
''' </exception>
'''
''' <exception cref="InvalidOperationException">
''' Only the thread that created the main window of the current application can call this to prevent a system shutdown.
''' </exception>
'''
''' <exception cref="SecurityException">
''' The user does not have the permissions required to create or modify 'AutoEndTasks' registry value.
''' Therefore, the application can't prevent a system shutdown.
''' </exception>
<DebuggerStepThrough>
Public Sub New(ByVal reason As String, Optional ByVal throwOnError As Boolean = True)
If Not Environment.UserInteractive Then
If (throwOnError) Then
Throw New InvalidOperationException(
"Applications without a user interface can't prevent a system shutdown.")
End If
End If
Dim pr As Process = Process.GetCurrentProcess()
Me.hRef = New HandleRef(pr, pr.MainWindowHandle)
If (Me.hRef.Handle = IntPtr.Zero) AndAlso (throwOnError) Then
Throw New InvalidOperationException(
"The main window of the current application is not yet created or is not visible.")
End If
Dim currentThreadId As UInteger = NativeMethods.GetCurrentThreadId()
Dim mainThreadId As Integer = NativeMethods.GetWindowThreadProcessId(Me.hRef.Handle, Nothing)
If (currentThreadId <> mainThreadId) AndAlso (throwOnError) Then
Throw New InvalidOperationException(
"Only the thread that created the main window of the current application can call this to prevent a system shutdown.")
End If
Me.previousAutoEndTasksValue = TweakingUtil.AutoEndTasks
If (Me.previousAutoEndTasksValue) Then
Try
TweakingUtil.AutoEndTasks = False
Catch ex As SecurityException
If (throwOnError) Then
Throw New SecurityException(
"The user does not have the permissions required to create or modify 'AutoEndTasks' registry value. " &
"Therefore, the application can't prevent a system shutdown.", ex)
End If
Catch ex As Exception
If (throwOnError) Then
Throw
End If
End Try
End If
AddHandler SystemEvents.SessionEnding, AddressOf Me.SessionEnding
Me.Reason = reason
End Sub
#End Region
#Region " Properties "
''' <summary>
''' Gets or sets the reason for which the current application must prevent system shutdown.
''' <para></para>
''' Because users are typically in a hurry when shutting down the system,
''' they may spend only a few seconds looking at the shutdown reasons that are displayed by the system.
''' Therefore, it is important that your reason strings are short and clear.
''' </summary>
''' <value>
''' The reason for which the current application must prevent system shutdown.
''' </value>
Public Property Reason As String
Get
Return Me.reason_
End Get
<DebuggerStepThrough>
Set(ByVal value As String)
If value.Equals(Me.reason_, StringComparison.Ordinal) Then
Exit Property
End If
Me.SetReason(value)
Me.reason_ = value
End Set
End Property
''' <summary>
''' ( backing field of <see cref="PreventShutdownContext.Reason"/> property )
''' <para></para>
''' The reason for which the application must prevent system shutdown.
''' </summary>
Private reason_ As String
#End Region
#Region " Event-Handlers "
''' <summary>
''' Handles the <see cref="Microsoft.Win32.SystemEvents.SessionEnding"/> event.
''' </summary>
''' <param name="sender">
''' The source of the event.
''' </param>
'''
''' <param name="e">
''' The <see cref="SessionEndingEventArgs"/> instance containing the event data.
''' </param>
Private Sub SessionEnding(ByVal sender As Object, e As SessionEndingEventArgs)
' By setting "e.Cancel" property to True,
' the application will respond 0 (zero) to "WM_QUERYENDSESSION" message in order to prevent a system shutdown.
'
' For more info:
' https://docs.microsoft.com/en-us/windows/desktop/shutdown/wm-queryendsession
' https://docs.microsoft.com/en-us/windows/desktop/Shutdown/shutdown-changes-for-windows-vista
e.Cancel = True
End Sub
#End Region
#Region " Private Methods "
''' <summary>
''' Sets the reason for which the current application must prevent system shutdown.
''' </summary>
''' <param name="reason">
''' The reason for which the current application must prevent system shutdown.
''' <para></para>
''' Because users are typically in a hurry when shutting down the system,
''' they may spend only a few seconds looking at the shutdown reasons that are displayed by the system.
''' Therefore, it is important that your reason strings are short and clear.
''' </param>
''' <exception cref="Win32Exception">
''' </exception>
<DebuggerStepThrough>
Private Sub SetReason(ByVal reason As String)
Dim succeed As Boolean
Dim win32Err As Integer
If (Me.isReasonCreated) Then
succeed = NativeMethods.ShutdownBlockReasonDestroy(Me.hRef.Handle)
win32Err = Marshal.GetLastWin32Error()
If Not succeed Then
Throw New Win32Exception(win32Err)
End If
End If
succeed = NativeMethods.ShutdownBlockReasonCreate(Me.hRef.Handle, reason)
win32Err = Marshal.GetLastWin32Error()
If Not succeed Then
Throw New Win32Exception(win32Err)
End If
Me.isReasonCreated = True
End Sub
#End Region
#Region " IDisposable Implementation "
''' <summary>
''' Flag to detect redundant calls when disposing.
''' </summary>
Private isDisposed As Boolean
''' <summary>
''' Releases all the resources used by this instance.
''' </summary>
<DebuggerStepThrough>
Public Sub Dispose() Implements IDisposable.Dispose
Me.Dispose(isDisposing:=True)
End Sub
''' <summary>
''' Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
''' Releases unmanaged and, optionally, managed resources.
''' </summary>
''' <param name="isDisposing">
''' <see langword="True"/> to release both managed and unmanaged resources;
''' <see langword="False"/> to release only unmanaged resources.
''' </param>
<DebuggerStepThrough>
Private Sub Dispose(ByVal isDisposing As Boolean)
If (Not Me.isDisposed) AndAlso (isDisposing) Then
RemoveHandler SystemEvents.SessionEnding, AddressOf Me.SessionEnding
NativeMethods.ShutdownBlockReasonDestroy(Me.hRef.Handle)
Me.isReasonCreated = False
Try
TweakingUtil.AutoEndTasks = Me.previousAutoEndTasksValue
Catch
End Try
End If
Me.isDisposed = True
End Sub
#End Region
End Class