深入浅出MFC文档/视图架构之文档模板(2)

2.文档模板类CDocTemplate

　　文档模板类CDocTemplate是一个抽象基类（这意味着不能直接用它来定义对象而必须用它的派生类），它定义了文档模板的基本处理函数接口。对一个单文档界面程序，需使用单文档模板类CSingleDocTemplate，而对于一个多文档界面程序，需使用多文档模板类CMultipleDocTemplate。我们首先来看看CDocTemplate类的声明：

class CDocTemplate : public CCmdTarget
{
　DECLARE_DYNAMIC(CDocTemplate)

　// Constructors
　protected:
　　CDocTemplate(UINT nIDResource,CRuntimeClass* pDocClass,CRuntimeClass* pFrameClass,CRuntimeClass* pViewClass);

　public:
　　virtual void LoadTemplate();

　　// Attributes
　public:
　　// setup for OLE containers
　　void SetContainerInfo(UINT nIDOleInPlaceContainer);

　　// setup for OLE servers
　　void SetServerInfo(UINT nIDOleEmbedding,UINT nIDOleInPlaceServer = 0,
CRuntimeClass* pOleFrameClass = NULL,CRuntimeClass* pOleViewClass = NULL);

　　// iterating over open documents
　　virtual POSITION GetFirstDocPosition() const = 0;
　　virtual CDocument* GetNextDoc(POSITION& rPos) const = 0;

　　// Operations
　public:
　　virtual void AddDocument(CDocument* pDoc); // must override
　　virtual void RemoveDocument(CDocument* pDoc); // must override
　　enum DocStringIndex
　　{
　　　windowTitle,// default window title
　　　docName,// user visible name for default document
　　　fileNewName,// user visible name for FileNew
　　　// for file based documents:
　　　filterName,// user visible name for FileOpen
　　　filterExt,// user visible extension for FileOpen
　　　// for file based documents with Shell open support:
　　　regFileTypeId,// REGEDIT visible reGIStered file type identifier
　　　regFileTypeName,// Shell visible registered file type name
　　};
　　virtual BOOL GetDocString(CString& rString,
enum DocStringIndex index) const; // get one of the info strings
　　CFrameWnd* CreateOleFrame(CWnd* pParentWnd,CDocument* pDoc,BOOL bCreateView);

　　// Overridables
　public:
　　enum Confidence
　　{
　　　noAttempt,
　　　maybeAttemptForeign,
　　　maybeAttemptNative,
　　　yesAttemptForeign,
　　　yesAttemptNative,
　　　yesAlreadyOpen
　　};
　　virtual Confidence MatchDocType(LPCTSTR lpszPathName,CDocument*& rpDocMatch);
　　virtual CDocument* CreateNewDocument();
　　virtual CFrameWnd* CreateNewFrame(CDocument* pDoc,CFrameWnd* pOther);
　　virtual void InitialUpdateFrame(CFrameWnd* pFrame,BOOL bMakeVisible = TRUE);
　　virtual BOOL SaveAllModified(); // for all documents
　　virtual void CloseAllDocuments(BOOL bEndSession);
　　virtual CDocument* OpenDocumentFile(
　　　LPCTSTR lpszPathName,BOOL bMakeVisible = TRUE) = 0;
　　　// open named file
　　　// if lpszPathName == NULL => create new file with this type
　　virtual void SetDefaultTitle(CDocument* pDocument) = 0;

　　// Implementation
　public:
　　BOOL m_bAutoDelete;
　　virtual ~CDocTemplate();

　　// back pointer to OLE or other server (NULL if none or disabled)
　　CObject* m_pAttachedFactory;

　　// menu & accelerator resources for in-place container
　　HMENU m_hMenuInPlace;
　　HACCEL m_hAccelInPlace;

　　// menu & accelerator resource for server editing embedding
　　HMENU m_hMenuEmbedding;
　　HACCEL m_hAccelEmbedding;

　　// menu & accelerator resource for server editing in-place
　　HMENU m_hMenuInPlaceServer;
　　HACCEL m_hAccelInPlaceServer;

　　#ifdef _DEBUG
　　　virtual void Dump(CDumpContext&) const;
　　　virtual void AssertValid() const;
　　#endif
　　virtual void OnIdle(); // for all documents
　　virtual BOOL OnCmdMsg(UINT nID,int nCode,void* pExtra,AFX_CMDHANDLERINFO* pHandlerInfo);

　protected:
　　UINT m_nIDResource; // IDR_ for frame/menu/accel as well
　　UINT m_nIDServerResource; // IDR_ for OLE inplace frame/menu/accel
　　UINT m_nIDEmbeddingResource; // IDR_ for OLE open frame/menu/accel
　　UINT m_nIDContainerResource; // IDR_ for container frame/menu/accel

　　CRuntimeClass* m_pDocClass; // class for creating new documents
　　CRuntimeClass* m_pFrameClass; // class for creating new frames
　　CRuntimeClass* m_pViewClass; // class for creating new views
　　CRuntimeClass* m_pOleFrameClass; // class for creating in-place frame
　　CRuntimeClass* m_pOleViewClass; // class for creating in-place view

　　CString m_strDocStrings; // '/n' separated names
　　// The document names sub-strings are represented as _one_ string:
　　// windowTitle/ndocName/n ... (see DocStringIndex enum)
};
　　文档模板挂接了后面要介绍的文档、视图和框架窗口，使得它们得以互相关联。通过文档模板，程序确定了创建或打开一个文档时，以什么样的视图和框架窗口来显示。文档模板依靠保存相互对应的文档、视图和框架窗口的CRuntimeClass对象指针来实现上述挂接，这就是文档模板类中的成员变量m_pDocClass、m_pFrameClass、m_pViewClass的由来。实际上，对m_pDocClass、m_pFrameClass、m_pViewClass的赋值在CDocTemplate类的构造函数中实施：

CDocTemplate::CDocTemplate(UINT nIDResource,
CRuntimeClass* pFrameClass,CRuntimeClass* pViewClass)
{
　ASSERT_VALID_IDR(nIDResource);
　ASSERT(pDocClass == NULL || pDocClass->IsDerivedFrom(RUNTIME_CLASS(CDocument)));
　ASSERT(pFrameClass == NULL ||pFrameClass->IsDerivedFrom(RUNTIME_CLASS(CFrameWnd)));
　ASSERT(pViewClass == NULL || pViewClass->IsDerivedFrom(RUNTIME_CLASS(CView)));

　m_nIDResource = nIDResource;
　m_nIDServerResource = NULL;
　m_nIDEmbeddingResource = NULL;
　m_nIDContainerResource = NULL;

　m_pDocClass = pDocClass;
　m_pFrameClass = pFrameClass;
　m_pViewClass = pViewClass;
　m_pOleFrameClass = NULL;
　m_pOleViewClass = NULL;

　m_pAttachedFactory = NULL;
　m_hMenuInPlace = NULL;
　m_hAccelInPlace = NULL;
　m_hMenuEmbedding = NULL;
　m_hAccelEmbedding = NULL;
　m_hMenuInPlaceServer = NULL;
　m_hAccelInPlaceServer = NULL;

　// add to pStaticList if constructed as static instead of on heap
　if (CDocManager::bStaticInit)
　{
　　m_bAutoDelete = FALSE;
　　if (CDocManager::pStaticList == NULL)
　　　CDocManager::pStaticList = new CPtrList;
　　if (CDocManager::pStaticDocManager == NULL)
　　　CDocManager::pStaticDocManager = new CDocManager;
　　　CDocManager::pStaticList->AddTail(this);
　}
　else
　{
　　m_bAutoDelete = TRUE; // usually allocated on the heap
　　LoadTemplate();
　}
}
　　文档模板类CDocTemplate还保存了它所支持的全部文档类的信息，包括所支持文档的文件扩展名、文档在框架窗口中的名字、图标等。

（编辑：北几岛）

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