在两个不同的程序实例中发送消息，相互通信 不错的代码结构
有时候，我们需要让不同的应用程序实例间相互发送消息，比如，为了确保对于同一个应用程序，只运行一个的实例，在启动程序时，先检测是否已有此程序的实例运行，如果有，则给此实例发送消息，通知它激活并保持最前，已提醒用户此程序已经在运行。利用Win32 API RegisterWindowMessage()可以实现这一功能。1.要点[*]用Win32 API RegisterWindowMessage()注册生成一个消息，此消息在整个Session中保持唯一，因此可用于同一个Session中不同的应用程序实例相互通信；[*]用PostMessage或SendMessage广播此消息；[*]需要接收处理此消息的程序实例，使用ON_REGISTERED_MESSAGE()宏接收处理此广播消息；2.实现代码1: //Define a unique const string to create the broadcast message2: //We can use the GuidGen tool to make sure this string is a unique one3: const static LPCTSTR g_AciveMsgName = _T("DBCAAC01-2744-43EE-9FFC-7CD41C672842");4: 5: //Generate a broadcast message6: UINT broadcastMsg = ::RegisterWindowMessage(g_AciveMsgName);7: 8: //Broadcast message9: ::PostMessage(HWND_BROADCAST,broadcastMsg,0,0); 10:11: //Receive and process this message,if the receiver is a different app instance,it need 12: //also to call the ::RegisterWindowMessage(g_AciveMsgName) API to get the message code 13: //NOTE:This message code is assotiated with the global unique string(g_AciveMsgName) 14: //and it's allocated by the windows system 15: BEGIN_MESSAGE_MAP(...) 16: //...... 17: ON_REGISTERED_MESSAGE(s_WM_ACTIVEWND,OnActiveWnd) 18: //...... 19: END_MESSAGE_MAP() 20:21: void CDlg::OnActiveWnd() 22: { 23: // Do something to response this broadcasted message 24: //...... 25: }
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