当系统的电源状态该变时，可以通过RequestPowerNotifications要求电源管理器向自己发送一个通知   HANDLE RequestPowerNotifications(   HANDLE hMsgQ,   DWORD Flags );   示例：   #include #include #include   #define MAX_NOTIFY_NAMELEN          128 #define PM_BROADCAST_QUEUE_SIZE     ((sizeof(POWER_BROADCAST) + (MAX_NOTIFY_NAMELEN * sizeof(WCHAR) ) ) )   #define SIZEOFARRAY(a)  (sizeof(a) / sizeof(a[0]))   void IlockDThreadProc(void) {      MSGQUEUEOPTIONS mqo;      HANDLE hPowerMsgQ;      HANDLE hPowerNotifications;      DWORD cbRead;     DWORD dwFlags;             DWORD cbPowerMsgSize =  PM_BROADCAST_QUEUE_SIZE;        DWORD dwPwrFlags;     TCHAR szPowerState[32];             POWER_BROADCAST ppb;     union {                          WCHAR buf[PM_BROADCAST_QUEUE_SIZE];          POWER_BROADCAST powerBroadcast;      } u;        printf("IlockDThreadProc/n");           mqo.dwSize = sizeof(MSGQUEUEOPTIONS);     mqo.dwFlags = MSGQUEUE_NOPRECOMMIT;     mqo.dwMaxMessages = 32;     mqo.cbMaxMessage = cbPowerMsgSize;     mqo.bReadAccess = TRUE;                      hPowerMsgQ = CreateMsgQueue(NULL, &mqo);     if (NULL == hPowerMsgQ) {         printf("/r/n/r/nCreateMsgQueue failed: %x/n", GetLastError());         goto Error;                   }     hPowerNotifications = RequestPowerNotifications(hPowerMsgQ, PBT_ALL); if (NULL == hPowerNotifications)    {         printf("RequestPowerNotifications failed: %x/n", GetLastError());         goto Error;     }       while(1)  {     WaitForSingleObject(hPowerMsgQ,INFINITE);                   if (!ReadMsgQueue(hPowerMsgQ, &u, cbPowerMsgSize, &cbRead, 0, &dwFlags))   {               printf("ReadMsgQueue failed: %x/n", GetLastError());             ASSERT(FALSE);         }                     ppb = u.powerBroadcast;                    switch(ppb.Message) {                case PBT_TRANSITION:                                         printf("##############################ppb.Message PBT_TRANSITION/n");                                            GetSystemPowerState(szPowerState,SIZEOFARRAY(szPowerState),&dwPwrFlags);                                                          if(!wcscmp(TEXT("backlightoff"),szPowerState)) {                        printf("BacklightOff/n");                         break;                    }                      if(!wcscmp(TEXT("unattended"),szPowerState))   {                        printf("unattended/n");                        break;                    }                                  break;         case PBT_RESUME:                    printf("##############################ppb.Message PBT_RESUME/n");               break;         case PBT_POWERSTATUSCHANGE:                    printf("************************ppb.Message PBT_POWERSTATUSCHANGE/n");               break;               case PBT_POWERINFOCHANGE:                    printf("##############################ppb.Message PBT_POWERINFOCHANGE/n");               break;         default:                    printf("##############################ppb.Message default/n");               break;           }                        }      Error:     if (hPowerMsgQ)         CloseMsgQueue(hPowerMsgQ);      if (hPowerNotifications)         StopPowerNotifications(hPowerNotifications);  }   int _tmain(void) {             CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)IlockDThreadProc,0,0,NULL);        while(1) {          Sleep(1000);      } }