使用WMI的电池FullChargeCapacity返回0

Question

我尝试在C++中使用WMI。在WMI类CIM_Battery,FullChargeCapacity值刚刚返回0.

有没有其他方法可以得到FullChargeCapacity？

我试过的代码是：

IWbemClassObject *pclsObj = NULL; 
ULONG uReturn = 0; 

while (pEnumerator) 
{ 
    HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1, 
     &pclsObj, &uReturn); 

    if (0 == uReturn) 
    { 
     break; 
    } 

    VARIANT vtProp; 

    // Get the value of the Name property 


    hr = pclsObj->Get(L"FullChargeCapacity", 0, &vtProp, 0, 0); 
    wcout << " FullChargeCapacity : " << vtProp.ulVal << endl; 
    VariantClear(&vtProp); 
    /*hr = pclsObj->Get(L"Name", 0, &vtProp, 0, 0); 
    wcout << " Name : " << vtProp.bstrVal << endl; 
    VariantClear(&vtProp);*/ 

    pclsObj->Release(); 
} 

Answer 1

当你想通了你自己，与WMI，你不会得到你想要的信息，你必须直接与电池司机交谈。

电池驱动程序通过I²C与电池通信并可以访问这些值。幸运的是，您可以使用一些特定于电池的IOCLT代码。

您首先需要知道电池驱动程序的deviceName。下面的方法使用SetupApi，但您也可以从登录处得到它HKEY_LOCAL_MACKINE\SYSTEM\CurrentControlSet\Services\CmBatt\Enum\0（假设您的电池使用了驱动程序CmBatt.sys驱动程序）。我建议使用SetupApi。

下面是一个辅助函数来获取DEVICENAME：

#include <Windows.h> 
#include <SetupAPI.h> 
#include <batclass.h> 
#include <devguid.h> 
#include <string> 
#include <iostream> 

#ifndef UNICODE 
typedef std::string String; 
#else 
typedef std::wstring String; 
#endif 

const String GetBatteryDevicePath(const int batteryIndex) 
{ 
    String result = TEXT(""); 
    HDEVINFO hDeviceInfoList = ::SetupDiGetClassDevs(&GUID_DEVCLASS_BATTERY, 0, 0, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE); 
    if (hDeviceInfoList != INVALID_HANDLE_VALUE) 
    { 
     SP_DEVICE_INTERFACE_DATA did = { 0 }; 
     did.cbSize = sizeof(did); 
     if (::SetupDiEnumDeviceInterfaces(hDeviceInfoList, 0, &GUID_DEVCLASS_BATTERY, batteryIndex, &did)) 
     { 
      DWORD dwRequiredSize = 0; 
      ::SetupDiGetDeviceInterfaceDetail(hDeviceInfoList, &did, 0, 0, &dwRequiredSize, 0); 
      if (GetLastError() == ERROR_INSUFFICIENT_BUFFER) 
      { 
       PSP_DEVICE_INTERFACE_DETAIL_DATA pdidd = (PSP_DEVICE_INTERFACE_DETAIL_DATA)::LocalAlloc(LPTR, dwRequiredSize); 
       if (pdidd) 
       { 
        pdidd->cbSize = sizeof(*pdidd); 
        if (::SetupDiGetDeviceInterfaceDetail(hDeviceInfoList, &did, pdidd, dwRequiredSize, &dwRequiredSize, 0)) 
        { 
         result = pdidd->DevicePath; 
        } 

        ::LocalFree(pdidd); 
       } 
      } 
     } 

     ::SetupDiDestroyDeviceInfoList(hDeviceInfoList); 
    } 

    return result; 
} 

之后，你就可以使用CreateFile打开的句柄电池设备：

const String devicePath = ::GetBatteryDevicePath(0); 

const auto hBattery = ::CreateFile(devicePath.c_str(), 
    GENERIC_READ | GENERIC_WRITE, 
    FILE_SHARE_READ | FILE_SHARE_WRITE, 
    NULL, 
    OPEN_EXISTING, 
    FILE_ATTRIBUTE_NORMAL, 
    NULL); 

现在我们所需要的电池tag，这是由驱动程序生成的电池的标识符。 F.E.如果更换电池，驱动程序将生成新标签。有了这个标签，我们可以查询电池信息的其余部分（见BATTERY_INFORMATION）：

if (hBattery != INVALID_HANDLE_VALUE) 
{ 
    DWORD dwBytesReturned, dwWait = 0; 
    BATTERY_QUERY_INFORMATION bqi = { 0 }; 
    // Query battery tag 
    if (::DeviceIoControl(hBattery, 
      IOCTL_BATTERY_QUERY_TAG, 
      &dwWait, 
      sizeof(dwWait), 
      &bqi.BatteryTag, 
      sizeof(bqi.BatteryTag), 
      &dwBytesReturned, 
      NULL) 
     && bqi.BatteryTag) 
    { 
     // Now we can query all other battery info 
     BATTERY_INFORMATION bi = { 0 }; 
     if (::DeviceIoControl(hBattery, 
       IOCTL_BATTERY_QUERY_INFORMATION, 
       &bqi, 
       sizeof(bqi), 
       &bi, 
       sizeof(bi), 
       &dwBytesReturned, 
       NULL)) 
     { 
      std::cout << "FullChargedCapacity = " << bi.FullChargedCapacity << std::endl; 
      std::cout << "DesignedCapacity = " << bi.DesignedCapacity << std::endl; 
     } 
    } 

    ::CloseHandle(hBattery); 
} 

IOCTL代码和相关的结构是在MSDN Power Management Control Codes

UPDATE

概括为您的评论的要求，为了读出时间估算，请求bqi中的标签与之前的片段相同，然后查询BatteryEstimatedTime这样：

bqi.AtRate = 0; 
bqi.InformationLevel = BatteryEstimatedTime; 
ULONG lEstimatedTime; 
if (::DeviceIoControl(hBattery, 
     IOCTL_BATTERY_QUERY_INFORMATION, 
     &bqi, 
     sizeof(bqi), 
     &lEstimatedTime, 
     sizeof(lEstimatedTime), 
     &dwBytesReturned, 
     NULL)) 
{ 
    if (lEstimatedTime != BATTERY_UNKNOWN_TIME) 
     std::cout << "EstimatedTime = " << lEstimatedTime/60 << "m" << std::endl; 
    else 
     std::cout << "EstimatedTime = UNKNOWN" << std::endl; 
} 

用于读出实际的电压和容量：

BATTERY_WAIT_STATUS bws = { 0 }; 
BATTERY_STATUS bs = { 0 }; 
bws.BatteryTag = bqi.BatteryTag; 
if (::DeviceIoControl(hBattery, 
    IOCTL_BATTERY_QUERY_STATUS, 
    &bws, 
    sizeof(bws), 
    &bs, 
    sizeof(bs), 
    &dwBytesReturned, 
    NULL)) 
{ 
    if (bs.PowerState & BATTERY_CHARGING) 
     std::cout << "Battery is CHARGING" << std::endl; 
    if (bs.PowerState & BATTERY_DISCHARGING) 
     std::cout << "Battery is DISCHARGING" << std::endl; 
    if (bs.PowerState & BATTERY_POWER_ON_LINE) 
     std::cout << "Power on-line" << std::endl; 

    std::cout << "Battery voltage: " << bs.Voltage << "mV" << std::endl; 
    std::cout << "Battery capacity: " << bs.Capacity << "mW" << std::endl; 
} 

通过比较bs.Capacity对bi.FullChargedCapacity就可以得到电池的剩余容量的百分比表示。