1.初始化COM
WMI提供的API是基于COM的,所以必须首先执行CoInitializeEx和
CoInitializeSecurity函数,以便访问WMI。
CoInitializeSecurity函数,以便访问WMI。
这里需要如下定义和头文件:
#define_WIN32_DCOM
#include<windows.h>
#include<comdef.h>
#include<wbemidl.h>
#pragmacomment(lib,"wbemuuid.lib")
#include<iostream>
usingnamespace
std;
std;
·用CoInitializeEx函数初始化COM接口:
HRESULThr=
CoInitializeEx(0,COINIT_MULTITHREADED);
CoInitializeEx(0,COINIT_MULTITHREADED);
if(FAILED(hr))
{
returnFALSE;
}
注意这个FAILED的定义是:
#defineFAILED(hr)(((HRESULT)(hr))<
0)
#defineFAILED(hr)(((HRESULT)(hr))<
0)
·用CoInitializeSecurity函数注册并设置进程的默认的安全值:
hr=CoInitializeSecurity(
NULL,
// Security descriptor
-1, // COM negotiates authentication service
NULL,
// Authentication services
NULL,
// Reserved
RPC_C_AUTHN_LEVEL_DEFAULT, // Default authentication level for proxies
RPC_C_IMP_LEVEL_IMPERSONATE,// Default Impersonation level for proxies
NULL,
// Authentication info
EOAC_NONE,
// Additional capabilities of the client or server
NULL);
// Reserved
if(FAILED(hr))
{
CoUninitialize();
returnFALSE;
}
2.创建一个到WMI命名空间的连接
WMI并不是运行在我们自己的进程中,需要在WMI和我们的程序中创建一个连接。
·用CoCreateInstance函数来初始化IwbemLocator接口
IWbemLocator*pLoc
= 0;
= 0;
hr=
CoCreateInstance(
CoCreateInstance(
CLSID_WbemLocator,
0,
CLSCTX_INPROC_SERVER,
IID_IWbemLocator,
(LPVOID*)
&pLoc
&pLoc
);
if(FAILED(hr))
{
CoUninitialize();
returnFALSE;
}
·用IWbemLocator::ConnectServer方法连接到WMI
ConnectServer方法返回一个IWbemServices接口的代理,可以用来访问本地或是远程WMI命名空间。
IWbemServices*pSvc
= 0;
= 0;
hr=
pLoc->ConnectServer(
pLoc->ConnectServer(
BSTR(L"root\\CIMV2"),
NULL,
NULL,
0,
NULL,
0,
0,
&pSvc
);
if(FAILED(hr))
{
pLoc->Release();
CoUninitialize();
returnFALSE;
}
3. 设置WMI连接的安全属性
因为IWbemServices代理允许使用进程外对象,但是在COM中,如果没有设置安全属性,是不允许进程间互相访问的。所以需要用CoSetProxyBlanket函数设置IWbemServices代理的安全值。
hr=
CoSetProxyBlanket(
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(hr))
{
pSvc->Release();
pLoc->Release();
CoUninitialize();
returnFALSE;
}
4.执行自己需要的操作
WMI通过COM提供了许多用来访问系统数据的接口,这里我们要读取系统的BIOS信息。
·用IWbemServices指针向WMI发送请求,获取Win32_BIOS类的实例集合
IEnumWbemClassObject*pEnumerator
= NULL;
= NULL;
hr=
pSvc->ExecQuery(
pSvc->ExecQuery(
bstr_t("WQL"),
bstr_t("Select * FROM Win32_BIOS"),
WBEM_FLAG_FORWARD_ONLY |
WBEM_FLAG_RETURN_IMMEDIATELY,
NULL,
&pEnumerator
);
if(FAILED(hr))
{
pSvc->Release();
pLoc->Release();
CoUninitialize();
returnFALSE;
}
·遍历IEnumWbemClassObject,输出信息
IWbemClassObject*pclsObj=NULL;
while(pEnumerator)
{
ULONGuReturn
= 0;
= 0;
hr=
pEnumerator->Next(
pEnumerator->Next(
WBEM_INFINITE,
1,
&pclsObj,
&uReturn
);
if(0==
uReturn)
uReturn)
break;
VARIANTvtProp;
hr=
pclsObj->Get(L"Name",0,
&vtProp,0,
0);
pclsObj->Get(L"Name",0,
&vtProp,0,
0);
wcout<<
vtProp.bstrVal<<
endl;
vtProp.bstrVal<<
endl;
hr=
pclsObj->Get(L"Manufacturer",0,
&vtProp,0,
0);
pclsObj->Get(L"Manufacturer",0,
&vtProp,0,
0);
wcout<<
vtProp.bstrVal<<
endl;
vtProp.bstrVal<<
endl;
hr=
pclsObj->Get(L"Version",0,
&vtProp,0,
0);
pclsObj->Get(L"Version",0,
&vtProp,0,
0);
wcout<<
vtProp.bstrVal<<
endl;
vtProp.bstrVal<<
endl;
hr=
pclsObj->Get(L"CurrentLanguage",0,
&vtProp,0,
0);
pclsObj->Get(L"CurrentLanguage",0,
&vtProp,0,
0);
wcout<<
vtProp.bstrVal<<
endl;
vtProp.bstrVal<<
endl;
VariantClear(&vtProp);
}
if(pclsObj!=NULL){
pclsObj->Release();
}
if(pEnumerator!=NULL){
pEnumerator->Release();
}
5.释放资源
pSvc->Release();
pLoc->Release();
CoUninitialize();