I know that when Windows is shutting down, it sends a WM_QUERYENDSESSION message to each application. This makes it easy to detect when Windows is shutting down. However, is it possible to know if the computer going to power-off or is it going to restart after Windows has shutdown.
I am not particularly hopeful, considering the documentation at MSDN has this to say about WM_QUERYENDSESSION: "...it is not possible to determine which event is occurring," but the cumulative cleverness of stackoverflow never ceases to amaze me.
From here:
You can read the DWORD value from "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shutdown Setting" to determine what the user last selected from the Shut Down dialog.
A bit of a roundabout solution, but it should do the trick.
In Windows 7 (and probably also in Vista / 8 / Server) you could use the system events to track whether Windows is shutting down (and powering off the computer) or just restarting. Every time a shutdown/reboot is initiated (by any means - clicking the button in Start menu, or programmatically), Windows 7 writes one or two events in the System log, source USER32, event ID 1074. You can see these events recorded if you open the Event Viewer from Administrative Tools (filter the System log to see only ID 1074). The description (message) of these events contains the shutdown type. So you could parse the description of the most recent event of this type (after the shutdown was initiated), looking for the necessary word (shutdown, reboot/restart).
I didn't try to see the shutdown type written in the event when using the power button to gracefully shutdown Windows (I usually disable this function), but some site suggests that it states a "power off" type instead of "shutdown" - so check it out, if you need to be sure. Or simply look for a "reboot" type - if it's not found, then a "shutdown" type is assumed.
In Windows XP, from my experience, an event 1074 is recorded only if the shutdown/reboot is done programmatically (e.g. during a program install or using the shutdown.exe utility). So it does not register the shutdowns initiated from the shell (Explorer), but perhaps you could combine this method with reading the value from registry as proposed in another answer. Also, keep in mind that in WinXP the message of event 1074 contains the word "restart" no matter what the real type of shutdown is, so you should look at the "Shutdown Type:" field, which will state either "shutdown" or "reboot".
Related to this, an event ID 1073 is recorded whenever Windows fails to shutdown/reboot for some reason (e.g. if an application doesn't allow to shutdown as a response to WM_QUERYENDSESSION). In that case the message will also contain words as "shutdown", "reboot" or "power off" - in WinXP. For Win7 this type of event is less useful in our case, since it won't make any difference between shutdown and reboot. But for WinXP - if you only need to intercept the shutdown/reboot, perform some actions, then continue the corresponding shutdown or reboot process - it should work as expected.
A trick that usually works is to trap WM_ENDSESSION and log it. Now keep track of the time. If the system comes back up within a reasonable peroid (say 5 minutes). Then that was a reboot, not a shutdown.
Idea: If the system comes back up within 5 minutes, does it really matter if the user clicked 'shutdown' or 'reboot'?
If you really need to detect a shutdown (and the only reason I think you'd need to do this is if you're depending upon an obscure behavioral software difference between a shutdown vs a reboot) you could investigate API hooking of ExitWindowsEx and related functions but I don't recommend this approach. Rethink if you really need to detect this directly.
Possible experimental solution for Windows7 could be the following. (I'm not sure if this works well with other localizations, therefore I would call it a workaround)
using System.Diagnostics.Eventing.Reader;
namespace MyApp
{
public class RestartDetector : IDisposable
{
public delegate void OnShutdownRequsted(bool restart);
public OnShutdownRequsted onShutdownRequsted;
private EventLogWatcher watcher = null;
public RestartDetector()
{
try
{
EventLogQuery subscriptionQuery = new EventLogQuery(
"System", PathType.LogName, "*[System[Provider[@Name='USER32'] and (EventID=1074)]]");
watcher = new EventLogWatcher(subscriptionQuery);
// Make the watcher listen to the EventRecordWritten
// events. When this event happens, the callback method
// (EventLogEventRead) is called.
watcher.EventRecordWritten +=
new EventHandler<EventRecordWrittenEventArgs>(
EventLogEventRead);
// Activate the subscription
watcher.Enabled = true;
}
catch (EventLogReadingException e)
{
}
}
public void EventLogEventRead(object obj, EventRecordWrittenEventArgs arg)
{
bool restart = false;
try
{
// Make sure there was no error reading the event.
if (arg.EventRecord != null)
{
String[] xPathRefs = new String[1];
xPathRefs[0] = "Event/EventData/Data";
IEnumerable<String> xPathEnum = xPathRefs;
EventLogPropertySelector logPropertyContext = new EventLogPropertySelector(xPathEnum);
IList<object> logEventProps = ((EventLogRecord)arg.EventRecord).GetPropertyValues(logPropertyContext);
string[] eventData = (string[])logEventProps[0];
foreach (string attribute in eventData)
{
if (attribute.Contains("restart")) { restart = true; break; }
}
}
}
catch (Exception e)
{
}
finally
{
if (onShutdownRequsted != null) { onShutdownRequsted(restart); }
}
}
public void Dispose()
{
// Stop listening to events
if (watcher != null)
{
watcher.Enabled = false;
watcher.Dispose();
}
}
}
}
The following is an example of XML which is written to the event log when a PC is restarted:
- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
<Provider Name="USER32" />
<EventID Qualifiers="32768">1074</EventID>
<Level>4</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2015-12-15T11:10:43.000000000Z" />
<EventRecordID>90416</EventRecordID>
<Channel>System</Channel>
<Computer>WIN7PC</Computer>
<Security UserID="S-1-5-21-1257383181-1549154685-2724014583-1000" />
</System>
- <EventData>
<Data>C:\Windows\system32\winlogon.exe (WIN7PC)</Data>
<Data>WIN7PC</Data>
<Data>No title for this reason could be found</Data>
<Data>0x500ff</Data>
<Data>restart</Data>
<Data />
<Data>WIN7PC\WIN7PCUser</Data>
<Binary>FF00050000000000000000000000000000000000000000000000000000000000</Binary>
</EventData>
</Event>
来源：https://stackoverflow.com/questions/981306/how-to-detect-whether-windows-is-shutting-down-or-restarting