Windows 8.1之后，winows系統引入一種叫Connected Standby power model。其目的在于模擬手機關屏后能夠省電，而開屏時又能快速響應的特點。在windows 10中，又擴展了這種模式。有了conneted standby mode 和DisConnected standby mode.（https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby）

最主要的意思是睡眠的時候仍然聯網，比如：收郵件。進入CS 之后后臺仍然能夠收郵件，conneted standby 最主要的意思是睡眠的時候仍然聯網，比如：收郵件。進入CS 之后后臺仍然能夠收郵件，喚醒之后馬上就能看到新郵件。還有一種是 Disconnected Standby，就是睡眠的時候斷網(Modern Standby簡介 - WWW.LAB-Z.COM (lab-z.com))。

聽起來這都是windows的改善行為。但是對于傳統的windows api,或者從windows 7遷移過來的app，這是有影響。很多程序在用戶進入sleep的時候，會監聽 SystemEvents.PowerModeChanged += SystemEvents_PowerModeChanged 做一些保存的動作。但是在windows 10中，如果電源模式為Modern standby 的話，那么這個事件失效的。

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原來windows OS 引入 Desktop Activity Moderator? PowerRegisterSuspendResumeNotification 這個API來處理這個問題。

https://docs.microsoft.com/en-us/windows/win32/w8cookbook/desktop-activity-moderator? 來處理這個問題。

以下演示在代碼展示c#程序中如何使用這種方法。

using System; using System.Runtime.InteropServices; namespace PowerStatusChanged {class Program{static void Main(string[] args){IntPtr registrationHandle = new IntPtr();DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS recipient = new DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS();recipient.Callback = new DeviceNotifyCallbackRoutine(DeviceNotifyCallback);recipient.Context = IntPtr.Zero;IntPtr pRecipient = Marshal.AllocHGlobal(Marshal.SizeOf(recipient));Marshal.StructureToPtr(recipient, pRecipient, false);uint result = PowerRegisterSuspendResumeNotification(DEVICE_NOTIFY_CALLBACK, ref recipient, ref registrationHandle);if (result != 0)Console.WriteLine("Error registering for power notifications: " + Marshal.GetLastWin32Error());elseConsole.WriteLine("Successfully Registered for power notifications!");Console.ReadKey();}private static int DeviceNotifyCallback(IntPtr context, int type, IntPtr setting){Console.WriteLine("Device notify callback called: ");switch (type){case PBT_APMPOWERSTATUSCHANGE:Console.WriteLine("\tPower status has changed.");break;case PBT_APMRESUMEAUTOMATIC:Console.WriteLine("\tOperation is resuming automatically from a low-power state.This message is sent every time the system resumes.");break;case PBT_APMRESUMESUSPEND:Console.WriteLine("\tOperation is resuming from a low-power state.This message is sent after PBT_APMRESUMEAUTOMATIC if the resume is triggered by user input, such as pressing a key.");break;case PBT_APMSUSPEND:Console.WriteLine("\tSystem is suspending operation.");break;case PBT_POWERSETTINGCHANGE:Console.WriteLine("\tA power setting change event has been received. ");break;default:Console.WriteLine("unknown");break;}// do something herereturn 0;}private const int WM_POWERBROADCAST = 536; // (0x218)private const int PBT_APMPOWERSTATUSCHANGE = 10; // (0xA) - Power status has changed.private const int PBT_APMRESUMEAUTOMATIC = 18; // (0x12) - Operation is resuming automatically from a low-power state.This message is sent every time the system resumes.private const int PBT_APMRESUMESUSPEND = 7; // (0x7) - Operation is resuming from a low-power state.This message is sent after PBT_APMRESUMEAUTOMATIC if the resume is triggered by user input, such as pressing a key.private const int PBT_APMSUSPEND = 4; // (0x4) - System is suspending operation.private const int PBT_POWERSETTINGCHANGE = 32787; // (0x8013) - A power setting change event has been received.private const int DEVICE_NOTIFY_CALLBACK = 2;/// <summary>/// OS callback delegate definition/// </summary>/// <param name="context">The context for the callback</param>/// <param name="type">The type of the callback...for power notifcation it's a PBT_ message</param>/// <param name="setting">A structure related to the notification, depends on type parameter</param>/// <returns></returns>public delegate int DeviceNotifyCallbackRoutine(IntPtr context, int type, IntPtr setting);/// <summary>/// A callback definition/// </summary>[StructLayout(LayoutKind.Sequential)]public struct DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS{public DeviceNotifyCallbackRoutine Callback;public IntPtr Context;}[DllImport("Powrprof.dll", SetLastError = true)]static extern uint PowerRegisterSuspendResumeNotification(uint flags, ref DEVICE_NOTIFY_SUBSCRIBE_PARAMETERS receipient, ref IntPtr registrationHandle);} }

源碼下載

https://download.csdn.net/download/mochounv/15728042

運行以上程序，點擊開始-->休眠，喚醒回來后，可以看到以下結果：

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以上代碼方案參考

ModernStandby下獲取系統電源消息_wayyt_新浪博客 (sina.com.cn)

pinvoke.net: PowerRegisterSuspendResumeNotification (powrprof)

值得分享的是：

1）以上程序在傳統的S3, S4電源模式下，也能響應系統Sleep事件。當將這代碼移到GUI程序（如wpf winform等程序時，需要將 registrationHandle，recipient 和 pRecipient 設置為 static 的成員，否則因為生命周期的問題，回調會找不到部分數據，而導致程序在OS resume 回來時掛掉）

2）這里想強調的時，雖然這里監聽的是PBT_APMSUSPEND事件，但是千萬不要在桌面程序的窗口事件WndindowProc來監聽，盡管有這樣一套接口官網有這樣一套接口

?https://docs.microsoft.com/en-us/windows/win32/power/wm-powerbroadcast#:~:text=WM_POWERBROADCAST%20messages%20do%20not%20distinguish%20between%20different%20low-power,state%20transitions%20in%20the%20Windows%20System%20event%20log.

但是我測下來，只能收到插播電源的事件。從以上鏈接看不出來為什么不行。

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一點擴展：

如何查看系統的電源模式呢，在cmd窗口中，使用powercfg -a 可以查看。

比如以下模式，就是一個傳統的電源模式， S3 (Sleep), S4(Hibernate).

而以下模式

S0 Low Power Idle表示 Modern standby 模式。

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至于什么是Modern standby 模式以及它跟傳統的 S3(Sleep), S4(Hibernate)有的區別可以查看

https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/modern-standby-vs-s3。

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