個人程式碼程式庫のC#只允許運行一個表單執行個體

using System;using System.Windows.Forms;using System.Runtime.InteropServices;//使用DllImport的必須。using System.Diagnostics;//引入Process 類namespace 命名空間{    static class Program    {        private const int WS_SHOWNORMAL = 1;        [DllImport("User32.dll")]        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);        [DllImport("User32.dll")]        private static extern bool SetForegroundWindow(IntPtr hWnd);        /// <summary>        /// 應用程式的主進入點。        /// </summary>        [STAThread]        static void Main()        {            Process instance = GetRunningInstance();            if (instance == null)            {                Application.EnableVisualStyles();                Application.SetCompatibleTextRenderingDefault(false);                Application.Run(new frm_Main());//在這啟動主表單。            }            else            {                HandleRunningInstance(instance);            }        }        /// <summary>        /// 擷取當前是否具有相同進程。        /// </summary>        /// <returns></returns>        public static Process GetRunningInstance()        {            Process current = Process.GetCurrentProcess();            Process[] processes = Process.GetProcessesByName(current.ProcessName);            //遍曆正在有相同名字啟動並執行常式               foreach (Process process in processes)            {                //忽略現有的常式                   if (process.Id != current.Id)                    //確保常式從EXE檔案運行                     if ( System.Reflection.Assembly.GetExecutingAssembly().Location.Replace("/" , "\\") == current.MainModule.FileName )                        return process;            }            return null;        }        /// <summary>        /// 啟用原有的進程。        /// </summary>        /// <param name="instance"></param>        public static void HandleRunningInstance(Process instance)        {            ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL);            SetForegroundWindow(instance.MainWindowHandle);        }    }}