Windows Management Instrumentation (WMI) 是 Microsoft 實做的 WBEM 及 CIM
它提供有彈性的介面讓電腦資訊便於管理及查詢
但儘管 Microsoft 宣稱 WMI 提供 Visual C++ 及 .Net Framework 相關語言的介面
很明顯它的設計僅為 .net-friendly
對於 Visual C++ 便依舊是苦工
在五月初的先期研究中
由於產出必須為綠色軟體的需求,我用 MFC 硬刻了一個雛型
但這樣的開發效率並不讓人滿意
為了有效提昇開發曲線,於是借助 Scripting Language 特性
將整體架構由 Pure-MFC 改為 MFC + VBScript
在此提出簡單範例,展示採用 Visual C++ 與 VBScript 對 WMI 查詢系統資訊的差異…
VBScript
若以 VBScript 實作,只需寥寥幾行便可完成:
Dim objWMIService, colSettings, objOS Dim strTmp Set objWMIService = GetObject ("winmgmts:\\.\root\cimv2") Set colSettings = objWMIService.ExecQuery("Select * from Win32_OperatingSystem") For Each objOS in colSettings strTmp = objOS.Caption Next Wsh.echo strTmp
Visual C++
相較之下 Visual C++ 的 code 便顯得臃腫不堪
儘管扣掉引入檔、例外處理以及註解,行數打個對折好了;所花的 effort 仍舊是 VBScript 的數倍!!
#define _WIN32_DCOM #include< iostream > using namespace std; #include< comdef.h > #include< Wbemidl.h > #pragma comment(lib, "wbemuuid.lib") int main(int argc, char **argv) { HRESULT hres; // Step 1: -------------------------------------------------- // Initialize COM. ------------------------------------------ hres = CoInitializeEx(0, COINIT_MULTITHREADED); if (FAILED(hres)) { cout << "Failed to initialize COM library. Error code = 0x" << hex << hres << endl; return 1; // Program has failed. } // Step 2: -------------------------------------------------- // Set general COM security levels -------------------------- // Note: If you are using Windows 2000, you need to specify - // the default authentication credentials for a user by using // a SOLE_AUTHENTICATION_LIST structure in the pAuthList ---- // parameter of CoInitializeSecurity ------------------------ 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 ); if (FAILED(hres)) { cout << "Failed to initialize security. Error code = 0x" << hex << hres << endl; CoUninitialize(); return 1; // Program has failed. } // Step 3: --------------------------------------------------- // 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; CoUninitialize(); return 1; // Program has failed. } // Step 4: ----------------------------------------------------- // Connect to WMI through the IWbemLocator::ConnectServer method IWbemServices *pSvc = NULL; // Connect to the root\cimv2 namespace with // the current user and obtain pointer pSvc // to make IWbemServices calls. hres = pLoc->ConnectServer( _bstr_t(L"ROOT\\CIMV2"), // 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 ); if (FAILED(hres)) { cout << "Could not connect. Error code = 0x" << hex << hres << endl; pLoc->Release(); CoUninitialize(); return 1; // Program has failed. } cout << "Connected to ROOT\\CIMV2 WMI namespace" << endl; // Step 5: -------------------------------------------------- // Set security levels on the proxy ------------------------- 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 ); if (FAILED(hres)) { cout << "Could not set proxy blanket. Error code = 0x" << hex << hres << endl; pSvc->Release(); pLoc->Release(); CoUninitialize(); return 1; // Program has failed. } // Step 6: -------------------------------------------------- // Use the IWbemServices pointer to make requests of WMI ---- // For example, get the name of the operating system IEnumWbemClassObject* pEnumerator = NULL; hres = pSvc->ExecQuery( bstr_t("WQL"), bstr_t("SELECT * FROM Win32_OperatingSystem"), WBEM_FLAG_FORWARD_ONLY | WBEM_FLAG_RETURN_IMMEDIATELY, NULL, &pEnumerator); if (FAILED(hres)) { cout << "Query for operating system name failed." << " Error code = 0x" << hex << hres << endl; pSvc->Release(); pLoc->Release(); CoUninitialize(); return 1; // Program has failed. } // Step 7: ------------------------------------------------- // Get the data from the query in step 6 ------------------- IWbemClassObject *pclsObj; 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"Name", 0, &vtProp, 0, 0); wcout << " OS Name : " << vtProp.bstrVal << endl; VariantClear(&vtProp); } // Cleanup // ======== pSvc->Release(); pLoc->Release(); pEnumerator->Release(); pclsObj->Release(); CoUninitialize(); return 0; // Program successfully completed. }
圖片來源:Developer Fusion