VC单实例运行

// SingleInstanceApp.cpp : header file
//
// CWinApp with single-instance support
//
// Copyright (C) 1997, 1998 Giancarlo Iovino (giancarlo@saria.com)
// All rights reserved. May not be sold for profit.
//
// Thanks to Kevin Lussier for the base idea.
//
// This code was developed for MFC Programmers SourceBook
// (http://www.codeguru.com)
//

#ifndef __AFXWIN_H__
    #error include 'stdafx.h' before including this file for PCH
#endif

#include "resource.h"       // main symbols

/////////////////////////////////////////////////////////////////////////////
// CSingleInstanceApp:
//

class CSingleInstanceApp : public CWinApp
{
public:
    // Construction/Destruction
    CSingleInstanceApp();
    ~CSingleInstanceApp();

    // Operations
    BOOL CheckSingleInstance(UINT nID);
    CString GetClassName() const;

protected:
    HANDLE m_hMutex;
    CString m_strClassName;
};


/////////////////////////////////////////////////////////////////////////////

// SingleInstanceApp.cpp : implementation file
//
// CWinApp with single-instance support
//
// Copyright (C) 1997, 1998 Giancarlo Iovino (giancarlo@saria.com)
// All rights reserved. May not be sold for profit.
//
// Thanks to Kevin Lussier for the base idea.
//
// This code was developed for MFC Programmers SourceBook
// (http://www.codeguru.com)
//

#include "stdafx.h"
#include "SingleInstanceApp.h"
#define _AFX_NO_OLE_SUPPORT
#include <../mfc/src/afximpl.h>

CSingleInstanceApp::CSingleInstanceApp()
{
    // Set our default values
    m_hMutex = NULL;
}

CSingleInstanceApp::~CSingleInstanceApp()
{
    // Release the mutex
    if ( m_hMutex != NULL ) {
        ReleaseMutex( m_hMutex );
    }
}

BOOL CSingleInstanceApp::CheckSingleInstance(UINT nID) {
    CString strFullString;

    // Generate a synthetic name for this class using the
    // AfxRegisterWndClass convention
    HINSTANCE hInst = AfxGetInstanceHandle();
    UINT nClassStyle = CS_DBLCLKS;    
    HCURSOR hCursor = LoadCursor(IDC_ARROW );
    HICON    hIcon = LoadIcon(MAKEINTRESOURCE( nID ) );    

    LPCTSTR lpstrAppName = AfxGetAppName();
    ASSERT(lpstrAppName != NULL);

    if (hCursor == NULL && hIcon == NULL)
        m_strClassName.Format(_T("%s:%x:%x"), lpstrAppName,
            (UINT)hInst, nClassStyle);
    else
        m_strClassName.Format(_T("%s:%x:%x:%x:%x"), lpstrAppName,
            (UINT)hInst, nClassStyle, (UINT)hCursor, (UINT)NULL);
    
    // Create the mutex with the class name
    m_hMutex = CreateMutex(NULL, FALSE, m_strClassName);
    // Check for errors
    if ( GetLastError() == ERROR_ALREADY_EXISTS ) {
        // Reset our mutex handle (just in case)
        m_hMutex = NULL;
        // The mutex already exists: an instance is already
        // running. Find the app window and bring it to foreground
        HWND hWnd = FindWindowEx(NULL, NULL, m_strClassName, NULL);
        if ( hWnd != NULL ) {
            ShowWindow( hWnd, SW_RESTORE );
            BringWindowToTop( hWnd );
            SetForegroundWindow( hWnd );
        }
    
        // Return failure
        return FALSE;
    }

    // Register the unique window class name
    WNDCLASS wndclass;    
    ZeroMemory(&wndclass, sizeof(WNDCLASS));

    wndclass.style = nClassStyle;
    wndclass.lpfnWndProc = AfxWndProc;
    wndclass.hInstance = hInst;
    wndclass.hIcon = hIcon; 
    wndclass.hCursor = hCursor;
    wndclass.hbrBackground = NULL;
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = m_strClassName; // The class name
    
    // Use AfxRegisterClass to register the class, exit if it fails
    if(!AfxRegisterClass(&wndclass)) {
        AfxMessageBox( _T("Failed to register window class!"), MB_ICONSTOP | MB_OK );
        // Return failure
        return FALSE;
    }

    // Return success
    return TRUE;
}

CString CSingleInstanceApp::GetClassName() const
{
    return m_strClassName;
}

使用:

调用 #include "SingleInstanceApp.h"

class CTestSingleApp : public CSingleInstanceApp 继承

BOOL CTestSingleApp::InitInstance()
{
    AfxEnableControlContainer();

    //判断单例运行
    BOOL bSingleInstance = CheckSingleInstance(IDR_MAINFRAME);    

    // 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

    // 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(CTestSingleDoc),
        RUNTIME_CLASS(CMainFrame),       // main SDI frame window
        RUNTIME_CLASS(CTestSingleView));
    AddDocTemplate(pDocTemplate);

    // Parse command line for standard shell commands, DDE, file open
    CCommandLineInfo cmdInfo;
    ParseCommandLine(cmdInfo);

    //保证单例子
    if (!bSingleInstance) {
        AfxMessageBox("此程序已运行!");
        return FALSE;
    }

    // Dispatch commands specified on the command line
    if (!ProcessShellCommand(cmdInfo))
        return FALSE;

    // The one and only window has been initialized, so show and update it.
    m_pMainWnd->ShowWindow(SW_SHOW);
    m_pMainWnd->UpdateWindow();

    return TRUE;
}

 代码下载：https://files.cnblogs.com/kenter/TestSingle.zip