【C#】檢測“程序已運行”，並切換到已運行程序界面

首先是添加API：

        /// 該函數設置由不同線程產生的窗口的顯示狀態
        /// </summary>
        /// <param name="hWnd">窗口句柄</param>
        /// <param name="cmdShow">指定窗口如何顯示。查看允許值列表，請查閱ShowWlndow函數的說明部分</param>
        /// <returns>如果函數原來可見，返回值爲非零；如果函數原來被隱藏，返回值爲零</returns>
        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
        /// <summary>
        ///  該函數將創建指定窗口的線程設置到前臺，並且激活該窗口。鍵盤輸入轉向該窗口，併爲用戶改各種可視的記號。
        ///  系統給創建前臺窗口的線程分配的權限稍高於其他線程。 
        /// </summary>
        /// <param name="hWnd">將被激活並被調入前臺的窗口句柄</param>
        /// <returns>如果窗口設入了前臺，返回值爲非零；如果窗口未被設入前臺，返回值爲零</returns>
        [DllImport("User32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);

        private const int SW_SHOWNOMAL = 1;
        private static void HandleRunningInstance(Process instance)
        {
            ShowWindowAsync(instance.MainWindowHandle, SW_SHOWNOMAL);//顯示
            SetForegroundWindow(instance.MainWindowHandle);//當到最前端
        }

        private static Process RuningInstance()
        {
            Process currentProcess = Process.GetCurrentProcess();
            Process[] Processes = Process.GetProcessesByName(currentProcess.ProcessName);
            foreach (Process process in Processes)
            {
                if (process.Id != currentProcess.Id)
                {
                    if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\")
			 == currentProcess.MainModule.FileName)
                    {
                        return process;
                    }
                }
            }
            return null;
        }

之後在程序加載開始：

        Process process = RuningInstance();
        if (process != null)
        {
                MessageBox.Show("應用程序已經在運行中。。。");
                HandleRunningInstance(process);
                //System.Threading.Thread.Sleep(1000);
                System.Environment.Exit(1);
        }