MFC学习笔记四——动态创建 Dynamic Creation

最新推荐文章于 2022-12-26 13:17:24 发布

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#mfc #class #constructor #pascal #null #struct

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本文介绍了一种使用MFC框架动态创建类实例的方法。通过定义CRuntimeClass结构体及其实现，使得运行时能够根据类名加载并创建相应的对象。文章展示了如何为不同的类声明动态创建，并提供了一个完整的示例程序。

动态创建 Dynamic Creation

//------------------------------------------------------------------- // MFC.H //------------------------------------------------------------------- #define BOOL int #define TRUE 1 #define FALSE 0 #define LPCSTR LPSTR typedef char* LPSTR; #define UINT int #define PASCAL _stdcall #define TRACE1 printf #include <iostream> #include <stdio.h> #include <string> using namespace std; class CObject; struct CRuntimeClass { LPCSTR m_lpszClassName; int m_nObjectSize; UINT m_wSchema; CObject* (PASCAL* m_pfnCreateObject)(); CRuntimeClass* m_pBaseClass; CObject* CreateObject(); static CRuntimeClass* PASCAL Load(); static CRuntimeClass* pFirstClass; CRuntimeClass* m_pNextClass; }; struct AFX_CLASSINIT { AFX_CLASSINIT(CRuntimeClass* pNewClass); }; #define RUNTIME_CLASS(class_name) / (&class_name::class##class_name) #define DECLARE_DYNAMIC(class_name) / public: / static CRuntimeClass class##class_name; / virtual CRuntimeClass* GetRuntimeClass() const; #define DECLARE_DYNCREATE(class_name) / DECLARE_DYNAMIC(class_name) / static CObject* PASCAL CreateObject(); #define _IMPLEMENT_RUNTIMECLASS(class_name,base_class_name,wSchema,pfnNew) / static char _lpsz##class_name[] = #class_name; / CRuntimeClass class_name::class##class_name = { / _lpsz##class_name, sizeof(class_name), wSchema, pfnNew, / RUNTIME_CLASS(base_class_name), NULL}; / static AFX_CLASSINIT _init_##class_name(&class_name::class##class_name); / CRuntimeClass* class_name::GetRuntimeClass() const / { return &class_name::class##class_name; } / #define IMPLEMENT_DYNMIC(class_name, base_class_name) / _IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, 65535, NULL) #define IMPLEMENT_DYNCREATE(class_name, base_class_name) / CObject* PASCAL class_name::CreateObject() / { return new class_name; } / _IMPLEMENT_RUNTIMECLASS(class_name,base_class_name,65535, class_name::CreateObject) class CObject { public: CObject::CObject() { } CObject::~CObject() { } virtual CRuntimeClass* GetRuntimeClass() const; BOOL IsKindOf(const CRuntimeClass* pClass) const; public: static CRuntimeClass classCObject; virtual void SayHello() { cout << "这里是CObject类 /n"; } }; class CCmdTarget : public CObject { DECLARE_DYNAMIC(CCmdTarget) public: CCmdTarget::CCmdTarget() { } CCmdTarget::~CCmdTarget() { } }; class CWinThread : public CCmdTarget { DECLARE_DYNAMIC(CWinThread) public: CWinThread::CWinThread() { } CWinThread::~CWinThread() { } virtual BOOL InitInstance() { return TRUE; } virtual int Run() { return 1; } }; class CWnd; class CWinApp : public CWinThread { DECLARE_DYNAMIC(CWinApp) public: CWinApp* m_pCurrentWinApp; CWnd* m_pMainWnd; public: CWinApp::CWinApp() { m_pCurrentWinApp = this; } CWinApp::~CWinApp() { } virtual BOOL InitApplication() { return TRUE; } virtual BOOL InitInstance() { return TRUE; } virtual int Run() { return CWinThread::Run(); } }; class CDocument : public CCmdTarget { DECLARE_DYNAMIC(CDocument) public: CDocument::CDocument() { } CDocument::~CDocument() { } }; class CWnd : public CCmdTarget { DECLARE_DYNCREATE(CWnd) public: CWnd::CWnd() { cout << "CWnd Constructor /n"; } CWnd::~CWnd() { } virtual BOOL Create(); BOOL CreateEx(); virtual BOOL PreCreateWindow(); void SayHello() { cout << "这里是CWnd类 /n"; } }; class CFrameWnd : public CWnd { DECLARE_DYNCREATE(CFrameWnd) public: CFrameWnd::CFrameWnd() { cout << "CFrameWnd Constructor /n"; } CFrameWnd::~CFrameWnd() { } virtual BOOL Create(); //BOOL CreateEx(); virtual BOOL PreCreateWindow(); void SayHello() { cout << "这里是CFrameWnd类 /n"; } }; class CView : public CWnd { DECLARE_DYNAMIC(CView) public: CView::CView() { } CView::~CView() { } }; //GLOBAL FUNC CWinApp* AfxGetApp(); //------------------------------------------------------------------- // MFC.CPP //------------------------------------------------------------------- #include "my.h" extern CMyWinApp theApp; static char szCObject[] = "CObject"; struct CRuntimeClass CObject::classCObject = { szCObject, sizeof(CObject),65535,NULL, NULL, NULL}; static AFX_CLASSINIT _init_CObject(&CObject::classCObject); CRuntimeClass* CRuntimeClass::pFirstClass = NULL; AFX_CLASSINIT::AFX_CLASSINIT(CRuntimeClass* pNewClass) { pNewClass->m_pNextClass = CRuntimeClass::pFirstClass; CRuntimeClass::pFirstClass = pNewClass; } CObject* CRuntimeClass::CreateObject() { if (m_pfnCreateObject == NULL) { TRACE1("错误：试图创建的对象不存在：%hs./n",m_lpszClassName); return NULL; } CObject* pObject = NULL; pObject = (*m_pfnCreateObject)(); return pObject; } CRuntimeClass* PASCAL CRuntimeClass::Load() { char szClassName[64]; CRuntimeClass* pClass; cout << " 输入一个类名" ; cin >> szClassName; for(pClass = pFirstClass;pClass!=NULL;pClass=pClass->m_pNextClass) { if (strcmp(szClassName, pClass->m_lpszClassName)==0) return pClass; } TRACE1("错误：没有找到匹配的类：%s /n",szClassName); return NULL; } CRuntimeClass* CObject::GetRuntimeClass()const { return &CObject::classCObject; } BOOL CObject::IsKindOf(const CRuntimeClass* pClass) const { CRuntimeClass* pClassThis = GetRuntimeClass(); while (pClassThis!=NULL) { if (pClassThis==pClass) { return TRUE; } pClassThis = pClassThis->m_pBaseClass; } return FALSE; } BOOL CWnd::Create() { return TRUE; } BOOL CWnd::CreateEx() { PreCreateWindow(); return TRUE; } BOOL CWnd::PreCreateWindow() { return TRUE; } BOOL CFrameWnd::Create() { CreateEx(); return TRUE; } BOOL CFrameWnd::PreCreateWindow() { return TRUE; } CWinApp* AfxGetApp() { return theApp.m_pCurrentWinApp; } IMPLEMENT_DYNMIC(CCmdTarget, CObject) IMPLEMENT_DYNMIC(CWinThread, CCmdTarget) IMPLEMENT_DYNMIC(CWinApp, CWinThread) IMPLEMENT_DYNMIC(CDocument, CCmdTarget) IMPLEMENT_DYNCREATE(CWnd, CCmdTarget) IMPLEMENT_DYNMIC(CView, CWnd) IMPLEMENT_DYNCREATE(CFrameWnd, CWnd) //------------------------------------------------------------------- // MY.H //------------------------------------------------------------------- #include <iostream> #include "MFC.h" class CMyWinApp : public CWinApp { public: CMyWinApp::CMyWinApp() { } CMyWinApp::~CMyWinApp() { } virtual BOOL InitInstance(); }; class CMyFrameWnd : public CFrameWnd { DECLARE_DYNCREATE(CMyFrameWnd) public: CMyFrameWnd::CMyFrameWnd(); CMyFrameWnd::~CMyFrameWnd() { } void sayHello() { cout << "这里是CMyFrameWnd类 /n"; } }; class CMyDoc : public CDocument { DECLARE_DYNCREATE(CMyDoc) public: CMyDoc::CMyDoc() { cout << "CMyDoc constructor /n";} CMyDoc::~CMyDoc() { } void sayHello() { cout << "这里是CMyDoc类 /n"; } }; class CMyView : public CView { DECLARE_DYNCREATE(CMyView) public: CMyView::CMyView() { cout << "CMyView constructor /n"; } CMyView::~CMyView() { } void sayHello() { cout << "这里是CMyView类 /n"; } }; //global function void AfxprintAllClasses(); //------------------------------------------------------------------- // MY.CPP //------------------------------------------------------------------- #include "MY.h" CMyWinApp theApp; BOOL CMyWinApp::InitInstance() { m_pMainWnd = new CMyFrameWnd; return TRUE; } CMyFrameWnd::CMyFrameWnd() { cout << "CMyDoc constructor /n"; Create(); } IMPLEMENT_DYNCREATE(CMyFrameWnd,CFrameWnd) IMPLEMENT_DYNCREATE(CMyDoc,CDocument) IMPLEMENT_DYNCREATE(CMyView,CView) void PrintAllClasses() { CRuntimeClass* pClass; for (pClass = CRuntimeClass::pFirstClass; pClass!=NULL; pClass = pClass->m_pNextClass) { cout<<pClass->m_lpszClassName<<endl; cout<<pClass->m_nObjectSize<<endl; cout<<pClass->m_wSchema<<endl; } } //------------------------------------------------------------------- // main //------------------------------------------------------------------- void main() { CWinApp* pApp = AfxGetApp(); pApp->InitApplication(); pApp->InitInstance(); pApp->Run(); CRuntimeClass* pClassRef; CObject* pOb; while (1) { if ((pClassRef = CRuntimeClass::Load())== NULL) { break; } pOb = pClassRef->CreateObject(); if (pOb!=NULL) { pOb->SayHello(); } } }

CWnd Constructor

CFrameWnd Constructor

CMyDoc constructor

输入一个类名CObject

错误：试图创建的对象不存在：CObject.

输入一个类名CView

错误：试图创建的对象不存在：CView.

输入一个类名CMyView

CWnd Constructor

CMyView constructor

这里是CWnd类

输入一个类名CMyFrameWnd