win7休眠、待机api_睡眠原因: application api

win7休眠、待机api

通过c++让windows进入休眠或者待机状态。
xp、win7下用SetSystemPowerState函数，vista及之后的版本使用 SetSuspendState函数。

xp、win7:

SetSystemPowerState

BOOL WINAPI SetSystemPowerState(
  _In_ BOOL fSuspend,
  _In_ BOOL fForce
);
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Parameters
fSuspend [in]
If this parameter is TRUE, the system is suspended. If the parameter is FALSE, the system hibernates.
参数值为真则待机，参数值为假则休眠。
fForce [in]
This parameter has no effect.

Return value
If power has been suspended and subsequently restored, the return value is nonzero.
If the system was not suspended, the return value is zero. To get extended error information, call GetLastError.

休眠与待机的区别
Suspends the system by shutting power down. Depending on the ForceFlag parameter, the function either suspends operation immediately or requests permission from all applications and device drivers before doing so.

待机是关闭电源（暂且将Suspends翻译为待机）。那么言下之意休眠就不是关闭电源了。那休眠是什么状态呢？硬盘关闭，风扇关闭，但是内存还上着电呢，用户点击鼠标或者键盘之后电脑就会自动恢复了。

而在待机状态下，点击鼠标键盘是不管用的，必须重新点开机按钮才行。开机后进入之前保留的状态。

臆想是上面那样的，而MicroSoft做了更细致的划分。

详细介绍如下

Remarks
The calling process must have the SE_SHUTDOWN_NAME privilege. To enable the SE_SHUTDOWN_NAME privilege, use the AdjustTokenPrivileges function. For more information, see Changing Privileges in a Token.
If any application or driver denies permission to suspend operation, the function broadcasts a PBT_APMQUERYSUSPENDFAILED event to each application and driver. If power is suspended, this function returns only after system operation is resumed and related WM_POWERBROADCAST messages have been broadcast to all applications and drivers.
This function is similar to the SetSuspendState function.
To compile an application that uses this function, define the _WIN32_WINNT macro as 0x0400 or later. For more information, see Using the Windows Headers.

调用此api需要特权，通过AdjustTokenPrivileges来获取特权。

示例

 HANDLE hToken;
 TOKEN_PRIVILEGES tp;
 LUID luid;
 if(::OpenProcessToken(GetCurrentProcess(),
        TOKEN_ADJUST_PRIVILEGES|TOKEN_QUERY,
        &hToken))
 {
  ::LookupPrivilegeValue(NULL,SE_SHUTDOWN_NAME,&luid);
  tp.PrivilegeCount=1;
  tp.Privileges[0].Luid =luid;
  tp.Privileges[0].Attributes =SE_PRIVILEGE_ENABLED;
  ::AdjustTokenPrivileges(hToken,false,&tp,sizeof(TOKEN_PRIVILEGES),NULL,NULL);
 }
 ::SetSystemPowerState(false,true);
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