Windows API一日一练(66)CreateWaitableTimer和SetWaitableTimer函数

用户感觉到软件的好用，就是可以定时地做一些工作，而不需要人参与进去。比如每天定时地升级病毒库，定时地下载电影，定时地更新游戏里的人物。要想实现这些功能，就可以使用定时器的API函数CreateWaitableTimer和SetWaitableTimer来实现了，这对API函数创建的时钟是比较精确的，可以达到100倍的10亿分之一秒。 函数CreateWaitableTimer和SetWaitableTimer声明如下： WINBASEAPI__outHANDLEWINAPICreateWaitableTimerA(    __in_opt LPSECURITY_ATTRIBUTES lpTimerAttributes,    __in     BOOL bManualReset,    __in_opt LPCSTR lpTimerName    );WINBASEAPI__outHANDLEWINAPICreateWaitableTimerW(    __in_opt LPSECURITY_ATTRIBUTES lpTimerAttributes,    __in     BOOL bManualReset,    __in_opt LPCWSTR lpTimerName    );#ifdef UNICODE#define CreateWaitableTimer CreateWaitableTimerW#else#define CreateWaitableTimer CreateWaitableTimerA#endif // !UNICODE  WINBASEAPIBOOLWINAPISetWaitableTimer(    __in     HANDLE hTimer,    __in     const LARGE_INTEGER *lpDueTime,    __in     LONG lPeriod,    __in_opt PTIMERAPCROUTINE pfnCompletionRoutine,    __in_opt LPVOID lpArgToCompletionRoutine,    __in     BOOL fResume    ); lpTimerAttributes是设置定时器的属性。bManualReset是是否手动复位。lpTimerName是定时器的名称。hTimer是定时器的句柄。lpDueTime是设置定时器时间间隔，当设置为正值是绝对时间；当设置为负数是相对时间。lPeriod是周期。pfnCompletionRoutine是设置回调函数。lpArgToCompletionRoutine是传送给回调函数的参数。fResume是设置系统是否自动恢复。 调用函数的例子如下：#001 //创建定时器#002  //蔡军生 2007/11/06 QQ:9073204 深圳#003  int CreateTestTimer(void)#004  {#005         HANDLE hTimer = NULL;#006         LARGE_INTEGER liDueTime;#007 #008         //设置相对时间为10秒。#009         liDueTime.QuadPart = -100000000;#010 #011         //创建定时器。#012        hTimer = CreateWaitableTimer(NULL, TRUE, _T("TestWaitableTimer"));#013         if (!hTimer)#014         {               #015               return 1;#016         }#017 #018         OutputDebugString(_T("10秒定时器/r/n"));#019 #020         // 设置10秒钟。#021        if (!SetWaitableTimer(hTimer, &liDueTime, 0, NULL, NULL, 0))#022         {         #023               //#024               CloseHandle(hTimer);#025               return 2;#026         }#027 #028         //等定时器有信号。#029         if (WaitForSingleObject(hTimer, INFINITE) != WAIT_OBJECT_0)#030         {#031               OutputDebugString(_T("10秒定时器出错了/r/n"));    #032               //#033               CloseHandle(hTimer);#034               return 3;#035         }#036         else#037         {#038               //10秒钟到达。#039               OutputDebugString(_T("10秒定时器到了/r/n"));             #040         }#041 #042         //#043         CloseHandle(hTimer);#044         return 0;#045  }