如何使用C++中的WMI从WIN32_NetworkAdapter检索值？我无法理解查询后用于访问值的VARIANT
问题描述：
- Win_32 NetworkAdapter，Win32_SignedDriver， 如何使用C++中的WMI从WIN32_NetworkAdapter检索值？我无法理解查询后用于访问值的VARIANT。
答
MSDN有大量关于WMI and C++的资源。另外，如果您是新来的从C++使用WMI，您可以使用WMI Delphi Code Creator，它允许您生成C++代码以访问WMI类，事件和方法。
尝试通过应用程序生成此示例代码
#include "stdafx.h"
#define _WIN32_DCOM
#include <iostream>
using namespace std;
#include <comdef.h>
#include <Wbemidl.h>
#pragma comment(lib, "wbemuuid.lib")
//CREDENTIAL structure
//http://msdn.microsoft.com/en-us/library/windows/desktop/aa374788%28v=vs.85%29.aspx
#define CRED_MAX_USERNAME_LENGTH 513
#define CRED_MAX_CREDENTIAL_BLOB_SIZE 512
#define CREDUI_MAX_USERNAME_LENGTH CRED_MAX_USERNAME_LENGTH
#define CREDUI_MAX_PASSWORD_LENGTH (CRED_MAX_CREDENTIAL_BLOB_SIZE/2)
#pragma argsused
int main(int argc, char* argv[])
{
wchar_t pszName[CREDUI_MAX_USERNAME_LENGTH+1] = L"user";
wchar_t pszPwd[CREDUI_MAX_PASSWORD_LENGTH+1] = L"password";
BSTR strNetworkResource;
//To use a WMI remote connection set localconn to false and configure the values of the pszName, pszPwd and the name of the remote machine in strNetworkResource
bool localconn = true;
strNetworkResource = localconn ? L"\\\\.\\root\\CIMV2" : L"\\\\remote--machine\\root\\CIMV2";
COAUTHIDENTITY *userAcct = NULL ;
COAUTHIDENTITY authIdent;
// Initialize COM. ------------------------------------------
HRESULT hres;
hres = CoInitializeEx(0, COINIT_MULTITHREADED);
if (FAILED(hres))
{
cout << "Failed to initialize COM library. Error code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
// Set general COM security levels --------------------------
if (localconn)
hres = CoInitializeSecurity(
NULL,
-1, // COM authentication
NULL, // Authentication services
NULL, // Reserved
RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication
RPC_C_IMP_LEVEL_IMPERSONATE, // Default Impersonation
NULL, // Authentication info
EOAC_NONE, // Additional capabilities
NULL // Reserved
);
else
hres = CoInitializeSecurity(
NULL,
-1, // COM authentication
NULL, // Authentication services
NULL, // Reserved
RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication
RPC_C_IMP_LEVEL_IDENTIFY, // Default Impersonation
NULL, // Authentication info
EOAC_NONE, // Additional capabilities
NULL // Reserved
);
if (FAILED(hres))
{
cout << "Failed to initialize security. Error code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
// Obtain the initial locator to WMI -------------------------
IWbemLocator *pLoc = NULL;
hres = CoCreateInstance(CLSID_WbemLocator, 0, CLSCTX_INPROC_SERVER, IID_IWbemLocator, (LPVOID *) &pLoc);
if (FAILED(hres))
{
cout << "Failed to create IWbemLocator object." << " Err code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
// Connect to WMI through the IWbemLocator::ConnectServer method
IWbemServices *pSvc = NULL;
if (localconn)
hres = pLoc->ConnectServer(
_bstr_t(strNetworkResource), // Object path of WMI namespace
NULL, // User name. NULL = current user
NULL, // User password. NULL = current
0, // Locale. NULL indicates current
NULL, // Security flags.
0, // Authority (e.g. Kerberos)
0, // Context object
&pSvc // pointer to IWbemServices proxy
);
else
hres = pLoc->ConnectServer(
_bstr_t(strNetworkResource), // Object path of WMI namespace
_bstr_t(pszName), // User name
_bstr_t(pszPwd), // User password
NULL, // Locale
NULL, // Security flags
NULL, // Authority
NULL, // Context object
&pSvc // IWbemServices proxy
);
if (FAILED(hres))
{
cout << "Could not connect. Error code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
pLoc->Release();
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
cout << "Connected to root\\CIMV2 WMI namespace" << endl;
// Set security levels on the proxy -------------------------
if (localconn)
hres = CoSetProxyBlanket(
pSvc, // Indicates the proxy to set
RPC_C_AUTHN_WINNT, // RPC_C_AUTHN_xxx
RPC_C_AUTHZ_NONE, // RPC_C_AUTHZ_xxx
NULL, // Server principal name
RPC_C_AUTHN_LEVEL_CALL, // RPC_C_AUTHN_LEVEL_xxx
RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
NULL, // client identity
EOAC_NONE // proxy capabilities
);
else
{
// Create COAUTHIDENTITY that can be used for setting security on proxy
memset(&authIdent, 0, sizeof(COAUTHIDENTITY));
authIdent.PasswordLength = wcslen (pszPwd);
authIdent.Password = (USHORT*)pszPwd;
authIdent.User = (USHORT*)pszName;
authIdent.UserLength = wcslen(pszName);
authIdent.Domain = 0;
authIdent.DomainLength = 0;
authIdent.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE;
userAcct = &authIdent;
hres = CoSetProxyBlanket(
pSvc, // Indicates the proxy to set
RPC_C_AUTHN_DEFAULT, // RPC_C_AUTHN_xxx
RPC_C_AUTHZ_DEFAULT, // RPC_C_AUTHZ_xxx
COLE_DEFAULT_PRINCIPAL, // Server principal name
RPC_C_AUTHN_LEVEL_PKT_PRIVACY, // RPC_C_AUTHN_LEVEL_xxx
RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
userAcct, // client identity
EOAC_NONE // proxy capabilities
);
}
if (FAILED(hres))
{
cout << "Could not set proxy blanket. Error code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
pSvc->Release();
pLoc->Release();
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
// Use the IWbemServices pointer to make requests of WMI ----
IEnumWbemClassObject* pEnumerator = NULL;
hres = pSvc->ExecQuery(L"WQL", L"SELECT * FROM Win32_NetworkAdapter",
WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &pEnumerator);
if (FAILED(hres))
{
cout << "ExecQuery failed" << " Error code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
pSvc->Release();
pLoc->Release();
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
// Secure the enumerator proxy
if (!localconn)
{
hres = CoSetProxyBlanket(
pEnumerator, // Indicates the proxy to set
RPC_C_AUTHN_DEFAULT, // RPC_C_AUTHN_xxx
RPC_C_AUTHZ_DEFAULT, // RPC_C_AUTHZ_xxx
COLE_DEFAULT_PRINCIPAL, // Server principal name
RPC_C_AUTHN_LEVEL_PKT_PRIVACY, // RPC_C_AUTHN_LEVEL_xxx
RPC_C_IMP_LEVEL_IMPERSONATE, // RPC_C_IMP_LEVEL_xxx
userAcct, // client identity
EOAC_NONE // proxy capabilities
);
if (FAILED(hres))
{
cout << "Could not set proxy blanket on enumerator. Error code = 0x" << hex << hres << endl;
cout << _com_error(hres).ErrorMessage() << endl;
pEnumerator->Release();
pSvc->Release();
pLoc->Release();
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 1; // Program has failed.
}
}
// Get the data from the WQL sentence
IWbemClassObject *pclsObj = NULL;
ULONG uReturn = 0;
while (pEnumerator)
{
HRESULT hr = pEnumerator->Next(WBEM_INFINITE, 1, &pclsObj, &uReturn);
if(0 == uReturn || FAILED(hr))
break;
VARIANT vtProp;
hr = pclsObj->Get(L"AdapterType", 0, &vtProp, 0, 0);// String
if (!FAILED(hr))
{
if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
wcout << "AdapterType : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
else
wcout << "AdapterType : " << vtProp.bstrVal << endl;
}
VariantClear(&vtProp);
hr = pclsObj->Get(L"AdapterTypeId", 0, &vtProp, 0, 0);// Uint16
if (!FAILED(hr))
{
if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
wcout << "AdapterTypeId : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
else
wcout << "AdapterTypeId : " << vtProp.uiVal << endl;
}
VariantClear(&vtProp);
hr = pclsObj->Get(L"Caption", 0, &vtProp, 0, 0);// String
if (!FAILED(hr))
{
if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
wcout << "Caption : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
else
wcout << "Caption : " << vtProp.bstrVal << endl;
}
VariantClear(&vtProp);
hr = pclsObj->Get(L"Description", 0, &vtProp, 0, 0);// String
if (!FAILED(hr))
{
if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
wcout << "Description : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
else
wcout << "Description : " << vtProp.bstrVal << endl;
}
VariantClear(&vtProp);
hr = pclsObj->Get(L"MACAddress", 0, &vtProp, 0, 0);// String
if (!FAILED(hr))
{
if ((vtProp.vt==VT_NULL) || (vtProp.vt==VT_EMPTY))
wcout << "MACAddress : " << ((vtProp.vt==VT_NULL) ? "NULL" : "EMPTY") << endl;
else
wcout << "MACAddress : " << vtProp.bstrVal << endl;
}
VariantClear(&vtProp);
pclsObj->Release();
pclsObj=NULL;
}
// Cleanup
pSvc->Release();
pLoc->Release();
pEnumerator->Release();
if (pclsObj!=NULL)
pclsObj->Release();
CoUninitialize();
cout << "press enter to exit" << endl;
cin.get();
return 0; // Program successfully completed.
}
答
查询返回接口的实例IEnumWbemClassObject接口。您可以使用它来枚举对象。对象以IWbemClassObject实例的形式返回。然后，您可以使用IWbemClassObject::Get方法来获取属性。
See this MSDN sample;然而，我通常使用CComPtr<> ATL类而不是原始接口指针，与CComVariant相比，原始VARIANT。
比方说，我访问Win32_NetworkAdapter.I说明成员正在试图打印值到文件中。当我在控制台上打印时，它很好，但在文件中有一些无法理解的值正在写入。你能给我一个片段什么的吗？ – user3194643
VARIANT vtProp; \t \t \t \t \t \t \t \t \t \t \t \t HR = pclsObj->获取（L “名称”，0，＆vtProp，0，0）; \t \t \t \t wcout 获取（L “DriverVersion”，0，＆vtProp，0，0）; \t \t \t \t wcout user3194643
我在MSDN上提供了完整的示例。关于bstrVal - 这就是为什么：http://msdn.microsoft.com/en-us/library/windows/desktop/ms221627(v=vs.85).aspx – Soonts