深入探索COM开发框架 之 MFC和ATL [四]

类别:VC语言 点击:0 评论:0 推荐:

static const AFX_DISPMAP* PASCAL _GetBaseDispatchMap(); \

       virtual const AFX_DISPMAP* GetDispatchMap() const; \

 

#else

#define DECLARE_DISPATCH_MAP() \

private: \

       static const AFX_DISPMAP_ENTRY _dispatchEntries[]; \

       static UINT _dispatchEntryCount; \

       static DWORD _dwStockPropMask; \

protected: \

       static AFX_DATA const AFX_DISPMAP dispatchMap; \

       virtual const AFX_DISPMAP* GetDispatchMap() const; \

#endif

------------------------------------------------------

#ifdef _AFXDLL

#define BEGIN_DISPATCH_MAP(theClass, baseClass) \

       const AFX_DISPMAP* PASCAL theClass::_GetBaseDispatchMap() \

                { return &baseClass::dispatchMap; } \

       const AFX_DISPMAP* theClass::GetDispatchMap() const \

                { return &theClass::dispatchMap; } \

       AFX_COMDAT const AFX_DISPMAP theClass::dispatchMap = \

                { &theClass::_GetBaseDispatchMap, &theClass::_dispatchEntries[0], \

                         &theClass::_dispatchEntryCount, &theClass::_dwStockPropMask }; \

       AFX_COMDAT UINT theClass::_dispatchEntryCount = (UINT)-1; \

       AFX_COMDAT DWORD theClass::_dwStockPropMask = (DWORD)-1; \

       AFX_COMDAT const AFX_DISPMAP_ENTRY theClass::_dispatchEntries[] = \

       { \

#else

#define BEGIN_DISPATCH_MAP(theClass, baseClass) \

       const AFX_DISPMAP* theClass::GetDispatchMap() const \

                { return &theClass::dispatchMap; } \

       AFX_COMDAT const AFX_DISPMAP theClass::dispatchMap = \

                { &baseClass::dispatchMap, &theClass::_dispatchEntries[0], \

                         &theClass::_dispatchEntryCount, &theClass::_dwStockPropMask }; \

       AFX_COMDAT UINT theClass::_dispatchEntryCount = (UINT)-1; \

       AFX_COMDAT DWORD theClass::_dwStockPropMask = (DWORD)-1; \

       AFX_COMDAT const AFX_DISPMAP_ENTRY theClass::_dispatchEntries[] = \

{ \

#endif

#define END_DISPATCH_MAP() \

       { VTS_NONE, DISPID_UNKNOWN, VTS_NONE, VT_VOID, \

                (AFX_PMSG)NULL, (AFX_PMSG)NULL, (size_t)-1, afxDispCustom } }; \

 

思路跟上面的接口映射表的如出一辙.这里不详细叙述.

关于Automation问题,我想过两天,专门写一篇文章谈谈.

因为Automation的确是一门范围很广的技术,不能说有多么的

难,不过细节很多,而且普遍的论述概念不清.

在上面几个宏中出现的结构倒需要提一下:

struct AFX_DISPMAP_ENTRY

{

       LPCTSTR lpszName;       // 分发的方法或属性名                        

       long lDispID;           // 接口分发ID (may be DISPID_UNKNOWN)

       LPCSTR lpszParams;      // 传递的参数

       WORD vt;                // 返回值类型或属性类型

       AFX_PMSG pfn;           // normal member On<membercall> or, OnGet<property>

       AFX_PMSG pfnSet;        // special member for OnSet<property>

       size_t nPropOffset;     // 偏移量,这个地方是核心

       AFX_DISPMAP_FLAGS flags;// flags (e.g. stock/custom)

};

struct AFX_DISPMAP

{

#ifdef _AFXDLL

       const AFX_DISPMAP* (PASCAL* pfnGetBaseMap)();

#else

       const AFX_DISPMAP* pBaseMap;

#endif

       const AFX_DISPMAP_ENTRY* lpEntries;

       UINT* lpEntryCount;

       DWORD* lpStockPropMask;  //是否用备用的名称

};

 

总之,即使在组件类寻到接口时,会按分发的方式来执行方法或更改属性,不会直接执行.

 

 

PART5-------组件得以使用的纽带:几个核心函数

 

  自然,组件的使用不是一呼既来的,从调用接口查询函数开始,

程序内部就开始了漫漫的寻找和创建过程 :

no1.

COleObjectFactory::RegisterAll();

在应用初始化时,调用.目的何在 ? 无非是注册类厂.

(这个地方,本人认为是加载了所有的类厂对象.

因为下面可以直接使用类厂指针链中的类厂指针了)

no2.

AFX_MANAGE_STATE(AfxGetStaticModuleState());

在MFC开发的以CwinApp对象为核心的

组件中, AFX_MANAGE_STATE(AfxGetStaticModuleState());

必须在具体操作前调用,因为它掌握着程序所有的信息.

而在ATL中,CcomModel对象,内部进行了协调.

一切行为由CcomModel对象来调度.

 

No3.

AfxDllGetClassObject(rclsid, riid, ppv);

你想得到希望的接口指针,获得类厂指针这一步是必须的.

而获得类厂指针是AfxDllGetClassObject(rclsid, riid, ppv);

完成的,它在使用前必须调用

AFX_MANAGE_STATE(AfxGetStaticModuleState());

来监视程序状态,

代码如下:

SCODE AFXAPI AfxDllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID* ppv)

{

        *ppv = NULL;

        DWORD lData1 = rclsid.Data1;

 

        // search factories defined in the application

        AFX_MODULE_STATE* pModuleState = AfxGetModuleState();

        AfxLockGlobals(CRIT_OBJECTFACTORYLIST);

        for (COleObjectFactory* pFactory = pModuleState->m_factoryList;

          pFactory != NULL; pFactory = pFactory->m_pNextFactory)

        {

                 if (pFactory->m_bRegistered != 0 &&

                   lData1 == pFactory->m_clsid.Data1 &&

                   ((DWORD*)&rclsid)[1] == ((DWORD*)&pFactory->m_clsid)[1] &&

                   ((DWORD*)&rclsid)[2] == ((DWORD*)&pFactory->m_clsid)[2] &&

                   ((DWORD*)&rclsid)[3] == ((DWORD*)&pFactory->m_clsid)[3])

                 {

                   // found suitable class factory -- query for correct interface

                   SCODE sc = pFactory->InternalQueryInterface(&riid, ppv);

                   AfxUnlockGlobals(CRIT_OBJECTFACTORYLIST);

                   return sc;

                 }

        }

        AfxUnlockGlobals(CRIT_OBJECTFACTORYLIST);

#ifdef _AFXDLL

        AfxLockGlobals(CRIT_DYNLINKLIST);

        // search factories defined in extension DLLs

        for (CDynLinkLibrary* pDLL = pModuleState->m_libraryList; pDLL != NULL;

          pDLL = pDLL->m_pNextDLL)

        {

          for (pFactory = pDLL->m_factoryList;

                   pFactory != NULL; pFactory = pFactory->m_pNextFactory)

                 {

                   if (pFactory->m_bRegistered != 0 &&

                             lData1 == pFactory->m_clsid.Data1 &&

                     ((DWORD*)&rclsid)[1] == ((DWORD*)&pFactory->m_clsid)[1] &&

                     ((DWORD*)&rclsid)[2] == ((DWORD*)&pFactory->m_clsid)[2] &&

                     ((DWORD*)&rclsid)[3] == ((DWORD*)&pFactory->m_clsid)[3])

                   {

                             // found suitable class factory -- query for correct interface

                             SCODE sc = pFactory->InternalQueryInterface(&riid, ppv);

                     AfxUnlockGlobals(CRIT_DYNLINKLIST);

                             return sc;

                   }

                 }

        }

        AfxUnlockGlobals(CRIT_DYNLINKLIST);

#endif

 

        // factory not registered -- return error

        return CLASS_E_CLASSNOTAVAILABLE;

}

 

代码简要说明:

在通过CLSID和IID调用组件导出函数DllGetClassObject时,首先

会监测程序环境,然后调用AfxDllGetClassObject,而AfxDllGetClassObject

内部的操作是这样的,它会从程序维护的全局信息中(

还有进线程信息、资源句柄等)的注册的类厂表中,根据CLSID搜索

相应的类厂,则从本dll引用的扩展dll中搜索.

 

OK !基本上,MFC对于COM的基础支持,就是通过上面这些宏

来实现的…

 

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待续                      ATL篇

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                          郑重声明:

                 允许复制、修改、传递或其它行为

                 但不准用于任何商业用途.

                      写于  1/4/2003

                      最后修改: 1/4/2003

                         By RedStar81

                      [email protected]

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