應用程序唯一性

程序啟動后，如果再次啟動程序，不會出現2個程序，或者實現如Notepad++已打開一個文件，再打開另外一個文件，則追加在Notepad++界面上。

使用codeproject上別人編寫的一個類，加在程序啟動時即可。

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sinstance.h

/*
Module : SINSTANCE.H
Purpose: Defines the interface for an MFC wrapper class to do instance checking
Created: PJN / 29-07-1998Copyright (c) 1996 - 2008 by PJ Naughter (Web: www.naughter.com, Email: pjna@naughter.com)All rights reserved.Copyright / Usage Details:You are allowed to include the source code in any product (commercial, shareware, freeware or otherwise) 
when your product is released in binary form. You are allowed to modify the source code in any way you want 
except you cannot modify the copyright details at the top of each module. If you want to distribute source 
code with your application, then you are only allowed to distribute versions released by the author. This is 
to maintain a single distribution point for the source code. *//// Macros / Defines //#pragma once#ifndef __SINSTANCE_H__
#define __SINSTANCE_H__#ifndef CSINGLEINSTANCE_EXT_CLASS
#define CSINGLEINSTANCE_EXT_CLASS
#endif#ifndef CSINGLEINSTANCE_EXT_API
#define CSINGLEINSTANCE_EXT_API
#endifIncludes /#ifndef __AFXMT_H__
#pragma message("To avoid this message, please put afxmt.h in your pre compiled header (normally stdafx.h)")
#include <afxmt.h>
#endifClasses //class CSINGLEINSTANCE_EXT_CLASS CInstanceChecker
{
public:
//Constructors / DestructorsCInstanceChecker(const CString& sUniqueName);virtual ~CInstanceChecker();//General functionsvoid ActivateChecker();BOOL TrackFirstInstanceRunning();BOOL PreviousInstanceRunning();HWND ActivatePreviousInstance(LPCTSTR lpCmdLine = NULL, ULONG_PTR dwCopyDataItemData = 0, DWORD dwTimeout = 30000); void QuitPreviousInstance(int nExitCode = 0);protected:
//Virtual methodsvirtual CString GetMMFFilename();virtual HWND GetWindowToTrack();//Standard non-virtual methodsvoid ReleaseLock();//DataCMutex       m_instanceDataMutex;CMutex       m_executeMutex;CSingleLock* m_pExecuteLock;CString      m_sName;
};#endif //__SINSTANCE_H__

　　sinstance.cpp

/*
Module : SINSTANCE.CPP
Purpose: Defines the implementation for an MFC wrapper classeto do instance checking
Created: PJN / 29-07-1998
History: PJN / 25-03-2000 Neville Franks made the following changes. Contact nevf@getsoft.com, www.getsoft.com1. Changed #pragma error to #pragma message. Former wouldn't compile under VC62. Replaced above #pragma with #include3. Added TrackFirstInstanceRunning(), MakeMMFFilename()PJN / 27-03-2000 1. Fixed a potential handle leak where the file handle m_hPrevInstance was not beingclosed under certain circumstances.Neville Franks made the following changes. Contact nevf@getsoft.com, www.getsoft.com2. Split PreviousInstanceRunning() up into separate functions so wecan call it without needing the MainFrame window.3. Changed ActivatePreviousInstance() to return hWnd.PJN / 15-05-2000 1. Serialized access to all of the CSingleInstance class to prevent race conditionswhich can occur when you app is programatically spawned.PJN / 17-05-2000 1. Updated sample to show how the code can be used for dialog based apps.PJN / 01-01-2001 1. Added a number of asserts to CInstanceChecker::ActivatePreviousInstance2. Now includes copyright message in the source code and documentation.PJN / 15-01-2001 1. Now allows multiple calls to PreviousInstanceRunning without ASSERTing2. Removed some unnecessary VERIFY's from ActivatePreviousInstance3. Made the MMF filename used modifiable via a virtual function GetMMFFilename 4. Made the window to track modifiable via a virtual function GetWindowToTrack5. Made destructor virtual since the introduction of other virtual functions in the class6. Removed a number of unnecessary verifies7. Changed the meaning of the return value from TrackFirstInstanceRunningPJN / 17-06-2001 1. Moved most of the code from CInstanceChecker::CInstanceChecker to CInstanceChecker::ActivateChecker. This allows client code to turn on or off the instancechecking code easily. Thanks to Anders Rundegren for this addition.PJN / 31-08-2001 1. made the name of the mutex which the class uses to serialize access to itself a paramterto the constructor. That way multiple independent apps do not block each other whilethey are calling into the CSingleInstance class. Thanks to Eugene Shmelyov for spottingthis problem.PJN / 23-03-2002 1. Provided a QuitPreviousInstance method. Thanks to Jon Bennett for providing this.PJN / 30-10-2002 1. The name of the internal memory mapped file is now based on the Mutex name rather thanthe application name. An example: a client was writing a webcam application and wanted it to run with multiple configuration for multiple camera support. So the app can run multiple times as long as a special configuration is given on the command line. But for that configuration only one instance is allowed. Using the application name for the memory mapped file was tying the single instance to the app rather than the unique mutex name. Thanks to Frank Fesevur for this nice update.PJN / 06-02-2003 1. Was missing a call to ReleaseLock in CInstanceChecker::ActivatePreviousInstance. Thanks to Pierrick Ingels for reporting this problem.PJN / 09-05-2004 1. Updated the copyright details.2. Extended CInstanceChecker::ActivatePreviousInstance to now allow the command line of thesecond app to be passed to the original app. By default the parameter is NULL, meaning that you get the original behaviour which just activates the previous instance. To respond to thisinformation you should add the following to your mainfrm module:mainfrm.hafx_msg LRESULT OnCopyData(WPARAM, LPARAM);mainfrm.cppLRESULT CMyFrameWnd::OnCopyData(WPARAM wParam, LPARAM lParam){COPYDATASTRUCT* pCDS = reinterpret_cast<COPYDATASTRUCT*>(lParam);TCHAR* pszCmdLine = static_cast<TCHAR*>(pCDS->lpData);if (pszCmdLine){//DO SOMETHING with pszCmdLine here such as call AfxGetApp()->OpenDocumentFile(pszCmdLine);}return TRUE;}Also hook up your onCopyData to the windows message map usingON_MESSAGE(WM_COPYDATA, OnCopyData)Thanks to Ingo H. de Boer for providing this nice update.3. Following a discussion on the Codeproject.com discussion forum for CSingleInstance on whatexactly a single instance app means (See http://www.codeproject.com/cpp/csingleinst.asp?msg=766108#xx1103xx),Daniel Lohmann has produced a simple function called CreateUniqueName which given a number of settings as flags, will produce a name which is unique. This code can be downloaded at http://www.losoft.de/code/SingleInstance.zip. You can then use this name in the constructor forCInstanceChecker. The concept of a single instance app is complicated by the concept of Window stationsand desktops as used by NT Services and Windows Terminal Services. In addition you might want to allow yourprogram to be run once per user. PJN / 30-05-2005 1. Fix for a crash where CWnd::GetLastActivePopup can sometimes return a NULL pointer. Thanks to Dominik Reichl for reporting this bug.PJN / 07-07-2006 1. Updated copyright details.2. Addition of CSINGLEINSTANCE_EXT_CLASS and CSINGLEINSTANCE_EXT_API which allows the class to be easily usedin an extension DLL.3. Removed derivation from CObject as it was not really needed.4. Updated the documentation to use the same style as the web site.5. Code now uses newer C++ style casts instead of C style casts.6. Fixed a number of level 4 warnings in the sample app.7. Updated code to compile cleanly using VC 2005.PJN / 17-03-2007 1. Updated copyright details.2. Optimized _INSTANCE_DATA constructor code3. Reworked how the method CInstanceChecker::GetMMFFilename creates the name of the memory mapped filenamethe code requires for sharing. Now the main instance name appears before the hard coded string. Thisensures that the CInstanceChecker class works correctly for terminal sessions i.e. kernel objects prefixedwith the value "Local\". Thanks to Mathias Berchtold for reporting this issue.4. Updated the sample app code to clean compile on VC 20055. QuitPreviousInstance now uses GetLastActivePopup API to ensure it posts the WM_QUIT message to the correct window of the previous instance.PJN / 02-02-2008 1. Updated copyright details2. Removed VC 6 style classwizard comments from the sample apps code3. Updated ActivatePreviousInstance method to support Win64 compliant data4. ActivatePreviousInstance now takes a "dwTimeout" parameter which it now uses internally as the timeout whencalling SendMessageTimeout instead of SendMessage. The code now uses SendMessageTimeout instead of SendMessage to ensure we do not hang if the previous instance itself is hung. Thanks to Paul Shore for suggesting this update.5. Updated the sample apps to clean compile on VC 2008Copyright (c) 1996 - 2008 by PJ Naughter (Web: www.naughter.com, Email: pjna@naughter.com)All rights reserved.Copyright / Usage Details:You are allowed to include the source code in any product (commercial, shareware, freeware or otherwise) 
when your product is released in binary form. You are allowed to modify the source code in any way you want 
except you cannot modify the copyright details at the top of each module. If you want to distribute source 
code with your application, then you are only allowed to distribute versions released by the author. This is 
to maintain a single distribution point for the source code. *//  Includes  //#include "stdafx.h"
#include "sinstance.h"/// Defines / Macros //#ifdef _DEBUG
#define new DEBUG_NEW
#endif/ Implementation ////struct which is put into shared memory
struct CWindowInstance
{HWND hMainWnd;
};//Class which is used as a static to ensure that we
//only close the file mapping at the very last chance
class _SINSTANCE_DATA
{
public:
//Constructors / Destructors_SINSTANCE_DATA();~_SINSTANCE_DATA();protected:
//Member variablesHANDLE hInstanceData;friend class CInstanceChecker;
};_SINSTANCE_DATA::_SINSTANCE_DATA() : hInstanceData(NULL)
{
}_SINSTANCE_DATA::~_SINSTANCE_DATA()
{if (hInstanceData != NULL){::CloseHandle(hInstanceData);hInstanceData = NULL;}
}static _SINSTANCE_DATA g_sinstanceData;CInstanceChecker::CInstanceChecker(const CString& sUniqueName) : m_executeMutex(FALSE, sUniqueName)
{//Hive away the unique name as we will also be using it for the name of the memory mapped filem_sName = sUniqueName;//Only one object of type CInstanceChecker should be createdASSERT(g_sinstanceData.hInstanceData == NULL);m_pExecuteLock = NULL;
}void CInstanceChecker::ActivateChecker()
{ASSERT(m_pExecuteLock == NULL);//Ensure there is only ever one CInstanceChecker instance //active at any one time throughout the systemm_pExecuteLock = new CSingleLock(&m_executeMutex, TRUE);
}CInstanceChecker::~CInstanceChecker()
{//Free up the instance lockReleaseLock();
}void CInstanceChecker::ReleaseLock()
{if (m_pExecuteLock){delete m_pExecuteLock;m_pExecuteLock = NULL;}  
}//Track the first instance of our App.
//return TRUE on success, else FALSE
BOOL CInstanceChecker::TrackFirstInstanceRunning()
{//If a previous instance is running, just return prematurelyif (PreviousInstanceRunning())return FALSE;//If this is the first instance then copy in our info into the shared memory//First create the MMFint nMMFSize = sizeof(CWindowInstance);g_sinstanceData.hInstanceData = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, nMMFSize, GetMMFFilename());if (g_sinstanceData.hInstanceData == NULL){TRACE(_T("Failed to create the MMF even though this is the first instance, you might want to consider overriding GetMMFFilename()\n"));return FALSE;}//Open the MMFCWindowInstance* pInstanceData = static_cast<CWindowInstance*>(MapViewOfFile(g_sinstanceData.hInstanceData, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize));ASSERT(pInstanceData != NULL);   //Opening the MMF should work//Lock the data prior to updating itCSingleLock dataLock(&m_instanceDataMutex, TRUE);pInstanceData->hMainWnd = GetWindowToTrack();UnmapViewOfFile(pInstanceData);//Since this will be the last function that will be called //when this is the first instance we can release the lockReleaseLock();return TRUE;
}// Returns TRUE if a previous instance of the App is running.
BOOL CInstanceChecker::PreviousInstanceRunning()
{//Try to open the MMF first to see if we are the second instanceHANDLE hPrevInstance = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());BOOL bPreviousInstance = (hPrevInstance != NULL);if (hPrevInstance)CloseHandle(hPrevInstance);return bPreviousInstance;
}CString CInstanceChecker::GetMMFFilename()
{CString sMMF(m_sName);sMMF += _T("_CInstanceChecker_MMF");return sMMF;
}HWND CInstanceChecker::GetWindowToTrack()
{//By default the window tracked will be the standard AfxGetMainWnd()ASSERT(AfxGetMainWnd() != NULL); //Did you forget to set up the mainfrm in InitInstance ?return AfxGetMainWnd()->GetSafeHwnd();
}//Activate the Previous Instance of our Application.
HWND CInstanceChecker::ActivatePreviousInstance(LPCTSTR lpCmdLine, ULONG_PTR dwCopyDataItemData, DWORD dwTimeout)
{//What will be the return value from this function (assume the worst)HWND hWindow = NULL;//Try to open the previous instances MMFHANDLE hPrevInstance = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());if (hPrevInstance){//Open up the MMFint nMMFSize = sizeof(CWindowInstance);CWindowInstance* pInstanceData = static_cast<CWindowInstance*>(MapViewOfFile(hPrevInstance, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize));if (pInstanceData) //Opening the MMF should work{//Lock the data prior to reading from itCSingleLock dataLock(&m_instanceDataMutex, TRUE);//activate the old windowASSERT(pInstanceData->hMainWnd); //Something gone wrong with the MMFhWindow = pInstanceData->hMainWnd;if (hWindow){CWnd wndPrev;wndPrev.Attach(hWindow);CWnd* pWndChild = wndPrev.GetLastActivePopup();//Restore the focus to the previous instance and bring it to the foregroundif (wndPrev.IsIconic())wndPrev.ShowWindow(SW_RESTORE);if (pWndChild)pWndChild->SetForegroundWindow();if (lpCmdLine){  //Send the current apps command line to the previous instance using WM_COPYDATACOPYDATASTRUCT cds;cds.dwData = dwCopyDataItemData;DWORD dwCmdLength = static_cast<DWORD>(_tcslen(lpCmdLine) + 1);cds.cbData = dwCmdLength * sizeof(TCHAR); TCHAR* pszLocalCmdLine = new TCHAR[dwCmdLength]; //We use a local buffer so that we can specify a constant parameter//to this function#if (_MSC_VER >= 1400)_tcscpy_s(pszLocalCmdLine, dwCmdLength, lpCmdLine);#else                                                 _tcscpy(pszLocalCmdLine, lpCmdLine);#endifcds.lpData = pszLocalCmdLine;CWnd* pMainWindow = AfxGetMainWnd();HWND hSender = NULL;if (pMainWindow)hSender = pMainWindow->GetSafeHwnd();//Send the message to the previous instance. Use SendMessageTimeout instead of SendMessage to ensure we //do not hang if the previous instance itself is hungDWORD_PTR dwResult = 0;if (SendMessageTimeout(hWindow, WM_COPYDATA, reinterpret_cast<WPARAM>(hSender), reinterpret_cast<LPARAM>(&cds),SMTO_ABORTIFHUNG, dwTimeout, &dwResult) == 0){//Previous instance is not responding to messageshWindow = NULL;}//Tidy up the heap memory we have useddelete [] pszLocalCmdLine;}//Detach the CWnd we were usingwndPrev.Detach();}//Unmap the MMF we were usingUnmapViewOfFile(pInstanceData);}//Close the file handle now that we CloseHandle(hPrevInstance);//When we have activate the previous instance, we can release the lockReleaseLock();}return hWindow;
}void CInstanceChecker::QuitPreviousInstance(int nExitCode)
{//Try to open the previous instances MMFHANDLE hPrevInstance = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, GetMMFFilename());if (hPrevInstance){// Open up the MMFint nMMFSize = sizeof(CWindowInstance);CWindowInstance* pInstanceData = static_cast<CWindowInstance*>(MapViewOfFile(hPrevInstance, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, nMMFSize));if (pInstanceData != NULL) //Opening the MMF should work{// Lock the data prior to reading from itCSingleLock dataLock(&m_instanceDataMutex, TRUE);//activate the old windowASSERT(pInstanceData->hMainWnd); //Something gone wrong with the MMF?HWND hWnd = pInstanceData->hMainWnd;//Ask it to exitHWND hChildWnd = GetLastActivePopup(hWnd);PostMessage(hChildWnd, WM_QUIT, nExitCode, 0);}//Close the file handle now that we CloseHandle(hPrevInstance);}
}

　　windows MFC下使用方法:

在InitInstance()中添加:
//Check for the previous instance as soon as possibleCInstanceChecker instanceChecker(_T("CInstanceChecker Example FrameWnd App"));instanceChecker.ActivateChecker(); if (instanceChecker.PreviousInstanceRunning()){CCommandLineInfo cmdInfo;ParseCommandLine(cmdInfo);AfxMessageBox(_T("Previous version detected, will now restore it"), MB_OK); instanceChecker.ActivatePreviousInstance(cmdInfo.m_strFileName);return FALSE;}...//Standard MFC stuff, create the mainframeCFrameWnd* pMainFrm = new CMyFrameWnd();if (!pMainFrm->Create(NULL, m_pszAppName))return FALSE;pMainFrm->ShowWindow(SW_SHOW);m_pMainWnd = pMainFrm;// If this is the first instance of our App then track it so any other instances can find usinstanceChecker.TrackFirstInstanceRunning();

　　如需實現像Notepad++追加在程序后面的效果,可在CFrameWnd中添加:

添加WM_COPYDATA消息響應

LRESULT CMyFrameWnd::OnCopyData(WPARAM /*wParam*/, LPARAM lParam)
{COPYDATASTRUCT* pCDS = reinterpret_cast<COPYDATASTRUCT*>(lParam);TCHAR* pszCmdLine = static_cast<TCHAR*>(pCDS->lpData);if (pszCmdLine){CString sMsg;sMsg.Format(_T("Another instance passed us the command line: %s"), pszCmdLine);AfxMessageBox(sMsg);}return TRUE;
}

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