1、在應(yīng)用程序類InitInstance()函數(shù)中判斷是否已有一個(gè)應(yīng)用程序?qū)嵗谶\(yùn)行。

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BOOL CMutexApp::InitInstance()

{

?????? //創(chuàng)建命名信標(biāo)對(duì)象。

?????? HANDLE hSem=CreateSemaphore(NULL,1,1,"維新");

?????? if(hSem)? //信標(biāo)對(duì)象創(chuàng)建成功。

?????? {

????????????? //信標(biāo)對(duì)象已經(jīng)存在，則程序已有一個(gè)實(shí)例在運(yùn)行。

????????????? if(ERROR_ALREADY_EXISTS==GetLastError())

????????????? {?????????????????

???????????????????? CloseHandle(hSem);????? //關(guān)閉信號(hào)量句柄。

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//獲取桌面窗口的一個(gè)子窗口。

???????????????????? HWND hWndPrev=::GetWindow(::GetDesktopWindow(),GW_CHILD);??

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???????????????????? while(::IsWindow(hWndPrev))

???????????????????? {

???????????????????? //判斷窗口是否有我們預(yù)先設(shè)置的標(biāo)記，如有，則是我們尋找的窗口，并將它激活。

??????????????????????????? if(::GetProp(hWndPrev,"維新"))??

??????????????????????????? {

??????????????????????????? //如果主窗口已最小化，則恢復(fù)其大小。

?????????????????????????????????? if (::IsIconic(hWndPrev))????

????????????????????????????????????????? ::ShowWindow(hWndPrev,SW_RESTORE);

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?????????????????????????????????? //將應(yīng)用程序的主窗口激活。

?????????????????????????????????? ::SetForegroundWindow(hWndPrev);

?????????????????????????????????? return FALSE;????????????????????? //退出實(shí)例。

??????????????????????????? }

??????????????????????????? //繼續(xù)尋找下一個(gè)窗口。

??????????????????????????? hWndPrev = ::GetWindow(hWndPrev,GW_HWNDNEXT);

???????????????????? }

???????????????????

???????????????????? AfxMessageBox("已有一個(gè)實(shí)例在運(yùn)行，但找不到它的主窗口！");

????????????? }

?????? }

?????? else

?????? {

????????????? AfxMessageBox("創(chuàng)建信標(biāo)對(duì)象失敗，程序退出！");

????????????? return FALSE;

?????? }

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?????? AfxEnableControlContainer();

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?????? // Standard initialization

?????? // If you are not using these features and wish to reduce the size

?????? //? of your final executable, you should remove from the following

?????? //? the specific initialization routines you do not need.

?????

#ifdef _AFXDLL

?????? Enable3dControls();???????????????????? // Call this when using MFC in a shared DLL

#else

?????? Enable3dControlsStatic();????? // Call this when linking to MFC statically

#endif

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?????? // Change the registry key under which our settings are stored.

?????? // TODO: You should modify this string to be something appropriate

?????? // such as the name of your company or organization.

?????? SetRegistryKey(_T("Local AppWizard-Generated Applications"));

?

?????? LoadStdProfileSettings();? // Load standard INI file options (including MRU)

?

?????? // Register the application's document templates.? Document templates

?????? //? serve as the connection between documents, frame windows and views.

?

?????? CSingleDocTemplate* pDocTemplate;

?????? pDocTemplate = new CSingleDocTemplate(

????????????? IDR_MAINFRAME,

????????????? RUNTIME_CLASS(CMutexDoc),

????????????? RUNTIME_CLASS(CMainFrame),?????? // main SDI frame window

????????????? RUNTIME_CLASS(CMutexView));

?????? AddDocTemplate(pDocTemplate);

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?????? // Parse command line for standard shell commands, DDE, file open

?????? CCommandLineInfo cmdInfo;

?????? ParseCommandLine(cmdInfo);

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?????? // Dispatch commands specified on the command line

?????? if (!ProcessShellCommand(cmdInfo))

????????????? return FALSE;

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?????? // The one and only window has been initialized, so show and update it.

?????? m_pMainWnd->ShowWindow(SW_SHOW);

?????? m_pMainWnd->UpdateWindow();

?

?????? return TRUE;

}

2、在框架類的OnCreate()函數(shù)中設(shè)置查找標(biāo)記。

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)

{

?????? if (CFrameWnd::OnCreate(lpCreateStruct) == -1)

????????????? return -1;

?????

?????? if (!m_wndToolBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD | WS_VISIBLE | CBRS_TOP

????????????? | CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||

????????????? !m_wndToolBar.LoadToolBar(IDR_MAINFRAME))

?????? {

????????????? TRACE0("Failed to create toolbar/n");

????????????? return -1;????? // fail to create

?????? }

?

?????? if (!m_wndStatusBar.Create(this) ||

????????????? !m_wndStatusBar.SetIndicators(indicators,

??????????????? sizeof(indicators)/sizeof(UINT)))

?????? {

????????????? TRACE0("Failed to create status bar/n");

????????????? return -1;????? // fail to create

?????? }

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?????? // TODO: Delete these three lines if you don't want the toolbar to

?????? //? be dockable

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?????? m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);

?????? EnableDocking(CBRS_ALIGN_ANY);

?????? DockControlBar(&m_wndToolBar);

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?????

?????? //設(shè)置查找標(biāo)記。

?????? ::SetProp(m_hWnd,"維新",(HANDLE)1);

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?????? return 0;

}

3、在程序退出是刪除設(shè)置的標(biāo)記，在框架類中響應(yīng)WM_DESTROY消息，進(jìn)行處理。

void CMainFrame::OnDestroy()

{

?????? CFrameWnd::OnDestroy();

?????

?????? // TODO: Add your message handler code here

?????? //刪除所設(shè)置的標(biāo)記。

?????? ::RemoveProp(m_hWnd,"維新");

}

至此，使應(yīng)用程序只運(yùn)行一個(gè)實(shí)例的功能就完成了。