Lesson 03_MFC应用程序的生与死

Lesson 03 MFC应用程序的生与死一、如何学习MFC1.使用Windows API开发程序以raw Windows API 开发程序，学习的路径是单纯的，条理分明的，你一定先从程序进入点开始，然后产生窗口类，然后产生窗口，然后取得消息，然后分辨消息，然后决定如何处理消息。

虽然动作繁琐，学习却容易。

图1 学习Windows API编程2．使用MFC编程（1）开始容易，学习困难，如图2图2 学习MFC编程以MFC开发程序，一开始很快速，因为开发工具会为你产生一个骨干程序，一般该有的各种界面一应俱全。

但是MFC的学习曲线十分陡峭，程序员从骨干程序出发一直到有能力修改程序代码以符合个人的需要，是一段不易攀登的峭壁。

（2）理解MFC的根本，学习变得容易，如图3如果我们了解Windows 程序的基本运行原理，并了解MFC 如何把这些基础动作整合起来，我们就能够使MFC 学习曲线的陡峭程度缓和下来。

因此能够迅速接受MFC，进而使用MFC。

一条似远实近的道路！图3 理解MFC的根本3．熟悉MFC的类层次结构MSDN MFC最主要的几个类及其继承关系。

二、MFC程序的来龙去脉MFC程序也是Windwos程序，有且只有一个全局对象theApp，当操作系统将程序加载并激活时，这个全局对象获得配置，其构造函数会先执行，比WinMain更早。

MFC实际上把WinMain内部操作封装在CWinApp中，把WndProc内部操作封装在CFrameWnd中：● CWinApp代表程序本体● CFrameWnd代表一个主窗口（1）CWinApp取代WinMain的地位MFC中CWinApp的声明：（文件：AFXWIN.H）Class CWinApp ：public CWinThread{// Attributes// Startup args (do not change)HINSTANCE m_hInstance;HINST ANCE m_hPrevInstance;LPTSTR m_lpCmdLine;int m_nCmdShow;……public:// Overridables// hooks for your initialization codevirtual BOOL InitApplication();……// overrides for implementationvirtual BOOL InitInstance();virtual int ExitInstance();// return app exit codevirtual int Run();virtual BOOL OnIdle(LONG lCount); // return TRUE if more idle processing……};其中记录主窗口句柄的变量在CWinApp的父类CWinThread中。

（文件：AFXWIN.H）class CWinThread : public CCmdTarget{public:// AttributesCWnd* m_pMainWnd; // main window (usually same AfxGetApp()->m_pMainWnd)CWnd* m_pActiveWnd; // active main window (may not be m_pMainWnd)BOOL m_bAutoDelete; // enables 'delete this' after thread termination// only valid while runningHANDLE m_hThread; // this thread's HANDLE……// Overridables// thread initializationvirtual BOOL InitInstance();// running and idle processingvirtual int Run();virtual BOOL PreT ranslateMessage(MSG* pMsg);virtual BOOL PumpMessage(); // low level message pumpvirtual BOOL OnIdle(LONG lCount); // return TRUE if more idle processing……};（2）CFrameWnd取代WndProc的地位CFrameWnd 主要掌管窗口，MFC内建了一个Message Map机制，会把消息自动送到与消息对应的特定函数中去；消息与处理函数之间的对应关系由程序员指定。

下面的宏把消息与其处理函数关联在一起：BEGIN_MESSAGE_MAP(CMyFrameWnd，CFrameWnd)ON_WM_PAINT()……END_MESSAGE_MAP与DECLARE_MESSAGE_MAP对应（3）应用程序对象theApp每个MFC应用程序都有且只有一个应用程序对象：theApp，当程序运行时，这个全局对象产生，于是其构造函数执行。

CWinApp类的构造函数内容如下：（文件：APPCORE.CPP）CWinApp::CWinApp（LPCTSTR lpszAppName）if (lpszAppName != NULL)m_pszAppName = _tcsdup(lpszAppName);elsem_pszAppName = NULL;// initialize CWinThread stateAFX_MODULE_STA TE* pModuleState = _AFX_CMDTARGET_GETSTA TE(); AFX_MODULE_THREAD_STA TE* pThreadState = pModuleState->m_thread; ASSERT(AfxGetThread() == NULL);pThreadState->m_pCurrentWinThread = this;ASSERT(AfxGetThread() == this);m_hThread = ::GetCurrentThread();m_nThreadID = ::GetCurrentThreadId();// initialize CWinApp stateASSERT(afxCurrentWinApp == NULL); // only one CWinApp object please pModuleState->m_pCurrentWinApp = this;ASSERT(AfxGetApp() == this);// in non-running state until WinMainm_hInstance = NULL;m_pszHelpFilePath = NULL;m_pszProfileName = NULL;m_pszRegistryKey = NULL;m_pszExeName = NULL;m_pRecentFileList = NULL;m_pDocManager = NULL;m_atomApp = m_atomSystemTopic = NULL;m_lpCmdLine = NULL;m_pCmdInfo = NULL;// initialize wait cursor statem_nWaitCursorCount = 0;m_hcurWaitCursorRestore = NULL;// initialize current printer statem_hDevMode = NULL;m_hDevNames = NULL;m_nNumPreviewPages = 0; // not specified (defaults to 1)// initialize DAO statem_lpfnDaoTerm = NULL; // will be set if AfxDaoInit called// other initializationm_bHelpMode = FALSE;m_nSafetyPoolSize = 512; // default size}CWinApp之中的成员变量因为theApp全局对象的产生而获得配置与初值。

（4）隐含的WinMaintheApp配置完成后，WinMain开始，其代码是MFC早已准备好并由链接器直接加到应用程序的代码中，代码如下，_tWinMain函数的“_t”是为了支持Unicode而准备的一个宏：（文件：APPMODUL.CPP）extern "C" int WINAPI_tWinMain(HINST ANCE hInstance, HINST ANCE hPrevInstance,LPTSTR lpCmdLine, int nCmdShow){// call shared/exported WinMainreturn AfxWinMain(hInstance, hPrevInstance, lpCmdLine, nCmdShow);}MFC程序的入口点：AfxWinMain：（文件：WINMAIN.CPP）// Standard WinMain implementation// Can be replaced as long as 'AfxWinInit' is called firstint AFXAPI AfxWinMain(HINST ANCE hInstance, HINST ANCE hPrevInstance,LPTSTR lpCmdLine, int nCmdShow){ASSERT(hPrevInstance == NULL);int nReturnCode = -1;CWinThread* pThread = AfxGetThread();CWinApp* pApp = AfxGetApp();// AFX internal initializationif (!AfxWinInit(hInstance, hPrevInstance, lpCmdLine, nCmdShow))goto InitFailure;// App global initializations (rare)if (pApp != NULL && !pApp->InitApplication())goto InitFailure;// Perform specific initializationsif (!pThread->InitInstance()){if (pThread->m_pMainWnd != NULL){TRACE0("Warning: Destroying non-NULL m_pMainWnd\n");pThread->m_pMainWnd->DestroyWindow();}nReturnCode = pThread->ExitInstance();goto InitFailure;}nReturnCode = pThread->Run();InitFailure:#ifdef _DEBUG// Check for missing AfxLockTempMap callsif (AfxGetModuleThreadState()->m_nTempMapLock != 0){TRACE1("Warning: Temp map lock count non-zero (%ld).\n",AfxGetModuleThreadState()->m_nTempMapLock);}AfxLockTempMaps();AfxUnlockTempMaps(-1);#endifAfxWinT erm();return nReturnCode;}（5）AfxWinMain的四个主要操作以及引发的行为：①AfxWinInit:内部初始化操作AfxWinInit是继CWinApp构造函数之后的第一个操作，以下为源代码：（文件：APPINIT.CPP）BOOL AFXAPI AfxWinInit(HINST ANCE hInstance, HINSTANCE hPrevInstance,LPTSTR lpCmdLine, int nCmdShow){ASSERT(hPrevInstance == NULL);// handle critical errors and avoid Windows message boxesSetErrorMode(SetErrorMode(0) |SEM_FAILCRITICALERRORS|SEM_NOOPENFILEERRORBOX);// set resource handlesAFX_MODULE_STA TE* pModuleState = AfxGetModuleState();pModuleState->m_hCurrentInstanceHandle = hInstance;pModuleState->m_hCurrentResourceHandle = hInstance;// fill in the initial state for the applicationCWinApp* pApp = AfxGetApp();if (pApp != NULL){// Windows specific initialization (not done if no CWinApp)pApp->m_hInstance = hInstance;pApp->m_hPrevInstance = hPrevInstance;pApp->m_lpCmdLine = lpCmdLine;pApp->m_nCmdShow = nCmdShow;pApp->SetCurrentHandles();}// initialize thread specific data (for main thread)if (!afxContextIsDLL)AfxInitThread();return TRUE;}②CWinApp::InitApplicationAfxWinInit之后的操作是pApp->InitApplication。