C，中的ManagementClass类

在 C++ 中，存在一组类库用于管理计算机上的硬件和软件资源，其中就包括 ManagementClass 类。ManagementClass 类是用于访问操作系统 WMI（Windows Management Instrumentation）服务的一种类，可以帮助程序员查询和修改系统信息。

简单来说，通过 ManagementClass 类，我们可以使用 WMI 查询并获得各种硬件和软件信息，如 CPU 架构、硬盘空间、进程信息等等。同时，也可以通过该类跟踪系统事件，例如登录／注销、磁盘空间的变化等。下面将对 ManagementClass 类的使用方法、常见应用场景以及一些示例代码进行详细介绍。

使用方法

首先，我们需要在代码中添加头文件"wbemidl.h"，然后定义一个 ManagementClass 对象。接下来，我们就可以通过该对象的方法进行对象查询、属性查询和方法调用等操作。ManagementClass 类中常用的方法包括：

1. CreateInstanceEnum method：通过指定 WQL 查询语句获取 ManagementObjectCollection 对象。

2. Get method：获取指定对象的属性或者方法。

3. InvokeMethod method：调用对象的方法。

下面以查询硬件信息为例进行说明。

示例1：查询 CPU 信息

在这个示例中，我们会使用 ManagementClass 类查询和输出 CPU 的名称、厂商、核心数和占用率等信息。此外，我们还会使用 CPU 占用率信息来实现一个简单的系统性能监控应用程序。请注意，示例代码中的异常处理被忽略了。

#include

#include

#pragma comment(lib, "wbemuuid.lib")

using namespace std;

int main()

{

HRESULT hres;

// Initialize COM library

hres = CoInitializeEx(0, COINIT_MULTITHREADED);

if (FAILED(hres))

{

cout << "Failed to initialize COM library. Error code: " << hres << endl;

return 1;

}

// Initialize security

hres = CoInitializeSecurity(

NULL,

-1,

NULL,

NULL,

RPC_C_AUTHN_LEVEL_DEFAULT,

RPC_C_IMP_LEVEL_IMPERSONATE,

NULL,

EOAC_NONE,

NULL

);

if (FAILED(hres))

{

cout << "Failed to initialize security. Error code: " << hres << endl;

CoUninitialize();

return 1;

}

// Initialize pointers

IWbemLocator* pLoc = NULL;

IWbemServices* pSvc = NULL;

IEnumWbemClassObject* pEnumerator = NULL;

IWbemClassObject* pclsObj = NULL;

// Connect to the WMI locatocer

hres = CoCreateInstance(

CLSID_WbemLocator,

0,

CLSCTX_INPROC_SERVER,

IID_IWbemLocator,

(LPVOID*)&pLoc

);

if (FAILED(hres))

{

cout << "Failed to create IWbemLocator object. Error code: " << hres << endl;

CoUninitialize();

return 1;

}

// Connect to the specified namespace

hres = pLoc->ConnectServer(

_bstr_t(L"ROOT\\CIMV2"),

NULL,

NULL,

0,

NULL,

0,

0,

&pSvc

);

if (FAILED(hres))

{

cout << "Could not connect to the specified namespace. Error code: " << hres << endl;

pLoc->Release();

CoUninitialize();

return 1;

}

// Set up security to get full access

hres = CoSetProxyBlanket(

pSvc,

RPC_C_AUTHN_WINNT,

RPC_C_AUTHZ_NONE,

NULL,

RPC_C_AUTHN_LEVEL_CALL,

RPC_C_IMP_LEVEL_IMPERSONATE,

NULL,

EOAC_NONE

);

if (FAILED(hres))

{

cout << "Could not set proxy blanket. Error code: " << hres << endl;

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Prepare the WQL query

hres = pSvc->ExecQuery(

bstr_t("WQL"),

bstr_t("SELECT * FROM Win32_Processor"),

WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,

NULL,

&pEnumerator);

if (FAILED(hres))

{

cout << "Failed to execute WQL query. Error code: " << hres << endl;

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Retrieve the data from the query

ULONG uReturn = 0;

VARIANT vtProp;

while (pEnumerator)

{

HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1,

&pclsObj, &uReturn);

if (0 == uReturn)

{

break;

}

// Get the CPU name and manufacturer

hr = pclsObj->Get(L"Name", 0, &vtProp, 0, 0);

wcout << "CPU Name: " << vtProp.bstrVal << endl;

VariantClear(&vtProp);

hr = pclsObj->Get(L"Manufacturer", 0, &vtProp, 0, 0);

wcout << "CPU Manufacturer: " << vtProp.bstrVal << endl;

VariantClear(&vtProp);

// Get the number of cores

hr = pclsObj->Get(L"NumberOfCores", 0, &vtProp, 0, 0);

cout << "Number of CPU cores: " << vtProp.iVal << endl;

VariantClear(&vtProp);

// Get the CPU usage

SYSTEM_INFO sysInfo;

GetSystemInfo(&sysInfo);

DWORD numProcessors = sysInfo.dwNumberOfProcessors;

PDH_STATUS status;

HQUERY hQuery;

HCOUNTER hCounter;

DWORD dwCounterType;

PDH_FMT_COUNTERVALUE counterVal;

TCHAR counterPathBuffer[MAX_PATH];

// Connect to the PDH library

status = PdhOpenQuery(NULL, 0, &hQuery);

if (status != ERROR_SUCCESS)

{

cout << "Could not connect to PDH library. Error code: " << status << endl;

pEnumerator->Release();

pclsObj->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Get the counter path

_stprintf_s(counterPathBuffer, MAX_PATH, _T("\\Processor(_Total)\\% Processor Time"));

status = PdhAddCounter(hQuery, counterPathBuffer, 0, &hCounter);

if (status != ERROR_SUCCESS)

{

cout << "Could not retrieve CPU counter path. Error code: " << status << endl;

PdhCloseQuery(hQuery);

pEnumerator->Release();

pclsObj->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Collect the performance data

status = PdhCollectQueryData(hQuery);

if (status != ERROR_SUCCESS)

{

cout << "Could not collect performance data. Error code: " << status << endl;

PdhCloseQuery(hQuery);

pEnumerator->Release();

pclsObj->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

Sleep(1000);

// Get the counter value

status = PdhCollectQueryData(hQuery);

if (status != ERROR_SUCCESS)

{

cout << "Could not retrieve performance data. Error code: " << status << endl;

PdhCloseQuery(hQuery);

pEnumerator->Release();

pclsObj->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

status = PdhGetFormattedCounterValue(hCounter, PDH_FMT_DOUBLE, &dwCounterType, &counterVal);

if (status != ERROR_SUCCESS)

{

cout << "Could not format counter value. Error code: " << status << endl;

PdhCloseQuery(hQuery);

pEnumerator->Release();

pclsObj->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Output the CPU usage

printf("\n");

printf("\rCPU Usage: %.2f %%", counterVal.doubleValue / numProcessors);

// Cleanup

PdhCloseQuery(hQuery);

pclsObj->Release();

}

// Cleanup

pEnumerator->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 0;

}

示例2：查询网络适配器信息

在这个示例中，我们会使用 ManagementClass 类查询和输出所有网络适配器的名称和 MAC 地址信息。

#include

#include

#pragma comment(lib, "wbemuuid.lib")

using namespace std;

int main()

{

HRESULT hres;

// Initialize COM library

hres = CoInitializeEx(0, COINIT_MULTITHREADED);

if (FAILED(hres))

{

cout << "Failed to initialize COM library. Error code: " << hres << endl;

return 1;

}

// Initialize security

hres = CoInitializeSecurity(

NULL,

-1,

NULL,

NULL,

RPC_C_AUTHN_LEVEL_DEFAULT,

RPC_C_IMP_LEVEL_IMPERSONATE,

NULL,

EOAC_NONE,

NULL

);

if (FAILED(hres))

{

cout << "Failed to initialize security. Error code: " << hres << endl;

CoUninitialize();

return 1;

}

// Initialize pointers

IWbemLocator* pLoc = NULL;

IWbemServices* pSvc = NULL;

IEnumWbemClassObject* pEnumerator = NULL;

IWbemClassObject* pclsObj = NULL;

// Connect to the WMI locatocer

hres = CoCreateInstance(

CLSID_WbemLocator,

0,

CLSCTX_INPROC_SERVER,

IID_IWbemLocator,

(LPVOID*)&pLoc

);

if (FAILED(hres))

{

cout << "Failed to create IWbemLocator object. Error code: " << hres << endl;

CoUninitialize();

return 1;

}

// Connect to the specified namespace

hres = pLoc->ConnectServer(

_bstr_t(L"ROOT\\CIMV2"),

NULL,

NULL,

0,

NULL,

0,

0,

&pSvc

);

if (FAILED(hres))

{

cout << "Could not connect to the specified namespace. Error code: " << hres << endl;

pLoc->Release();

CoUninitialize();

return 1;

}

// Set up security to get full access

hres = CoSetProxyBlanket(

pSvc,

RPC_C_AUTHN_WINNT,

RPC_C_AUTHZ_NONE,

NULL,

RPC_C_AUTHN_LEVEL_CALL,

RPC_C_IMP_LEVEL_IMPERSONATE,

NULL,

EOAC_NONE

);

if (FAILED(hres))

{

cout << "Could not set proxy blanket. Error code: " << hres << endl;

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Prepare the WQL query

hres = pSvc->ExecQuery(

bstr_t("WQL"),

bstr_t("SELECT * FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled = True"),

WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY,

NULL,

&pEnumerator);

if (FAILED(hres))

{

cout << "Failed to execute WQL query. Error code: " << hres << endl;

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 1;

}

// Retrieve the data from the query

ULONG uReturn = 0;

VARIANT vtProp;

while (pEnumerator)

{

HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1,

&pclsObj, &uReturn);

if (0 == uReturn)

{

break;

}

// Get the network adapter name and MAC address

hr = pclsObj->Get(L"Caption", 0, &vtProp, 0, 0);

wcout << "Network Adapter Name: " << vtProp.bstrVal << endl;

VariantClear(&vtProp);

hr = pclsObj->Get(L"MACAddress", 0, &vtProp, 0, 0);

wcout << "MAC Address: " << vtProp.bstrVal << endl;

VariantClear(&vtProp);

// Cleanup

pclsObj->Release();

}

// Cleanup

pEnumerator->Release();

pSvc->Release();

pLoc->Release();

CoUninitialize();

return 0;

}

常见应用场景

ManagementClass 类可以用于许多方面的应用，下面是一些常见的应用场景：

1. 系统性能监控：通过查询计算机的 CPU 占用率、内存利用率和磁盘空间等信息，可以编写一个系统资源监控应用程序，可以汇总和显示有关系统资源使用情况的信息。

2. 硬件信息收集：通过查询计算机的硬件信息（如 CPU、内存、硬盘、显卡等），可以实现自动化系统信息收集任务，以辅助系统管理和故障排除等工作。

3. 系统事件跟踪：可以通过查询 Windows 事件日志、进程列表和服务状态等信息，实现系统事件的实时跟踪和警告的通知，以实现有效的系统监控。

4. 应用程序管理：可以通过查询系统中运行的进程和服务，以及系统上的安装软件列表，对软件漏洞扫描、系统管理和安全监控等工作提供帮助。

总结

通过 ManagementClass 类，我们可以以编程的方式访问 WMI 服务，从而轻松查询和修改系统信息。这些信息包括各种硬件和软件资源的信息、事件日志记录和系统配置等等，可以用于许多计算机管理和应用程序管理任务。值得注意的是，查询系统信息时，应该使用正确的查询语句，以防止查询失败或者查询结果出现意外错误。 如果你喜欢我们三七知识分享网站的文章， 欢迎您分享或收藏知识分享网站文章 欢迎您到我们的网站逛逛喔！https://www.37seo.cn/