CComClassFactory2 Class

Статья
10/16/2008

This class implements the IClassFactory2 interface.

template <
   class license
>
class CComClassFactory2 : public IClassFactory2,
   public CComObjectRootEx<CComGlobalsThreadModel>,
      public license

Параметры

license
A class that implements the following static functions:
- static BOOL VerifyLicenseKey( BSTR bstr );
- static BOOL GetLicenseKey( DWORD dwReserved**, BSTR*** pBstr );
- static BOOL IsLicenseValid( );

Заметки

CComClassFactory2 implements the IClassFactory2 interface, which is an extension of IClassFactory. IClassFactory2 controls object creation through a license. A class factory executing on a licensed machine can provide a run-time license key. This license key allows an application to instantiate objects when a full machine license does not exist.

ATL objects normally acquire a class factory by deriving from CComCoClass. This class includes the macro DECLARE_CLASSFACTORY, which declares CComClassFactory as the default class factory. To use CComClassFactory2, specify the DECLARE_CLASSFACTORY2 macro in your object's class definition. For example:

class ATL_NO_VTABLE CMyClass2 :
   public CComObjectRootEx<CComSingleThreadModel>,
   public CComCoClass<CMyClass2, &CLSID_MyClass>,
   public IDispatchImpl<IMyClass, &IID_IMyClass, &LIBID_NVC_ATL_COMLib, /*wMajor =*/ 1, /*wMinor =*/ 0>,
   public IDispatchImpl<IMyDualInterface, &__uuidof(IMyDualInterface), &LIBID_NVC_ATL_COMLib, /* wMajor = */ 1, /* wMinor = */ 0>
{
public:
   DECLARE_CLASSFACTORY2(CMyLicense)

   // Remainder of class declaration omitted

CMyLicense, the template parameter to CComClassFactory2, must implement the static functions VerifyLicenseKey, GetLicenseKey, and IsLicenseValid. The following is an example of a simple license class:

class CMyLicense
{
protected:
   static BOOL VerifyLicenseKey(BSTR bstr)
   {
      USES_CONVERSION;
      return !lstrcmp(OLE2T(bstr), _T("My run-time license key"));
   }

   static BOOL GetLicenseKey(DWORD /*dwReserved*/, BSTR* pBstr) 
   {
      USES_CONVERSION;
      *pBstr = SysAllocString( T2OLE(_T("My run-time license key"))); 
      return TRUE;
   }

   static BOOL IsLicenseValid() {  return TRUE; }
};

CComClassFactory2 derives from both CComClassFactory2Base and license. CComClassFactory2Base, in turn, derives from IClassFactory2 and CComObjectRootEx< CComGlobalsThreadModel >.