程序只能运行一次

using System;using System.Collections.Generic;using System.Windows.Forms;using System.Runtime.InteropServices;using System.Diagnostics;using System.Reflection;namespace 程序只能运行一次{    static class Program    {        /// <summary>         /// 该函数设置由不同线程产生的窗口的显示状态。         /// </summary>         /// <param name="hWnd">窗口句柄</param>         /// <param name="cmdShow">指定窗口如何显示。查看允许值列表，请查阅ShowWlndow函数的说明部分。</param>         /// <returns>如果函数原来可见，返回值为非零；如果函数原来被隐藏，返回值为零。</returns>         [DllImport("User32.dll")]        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);        /// <summary>         /// 该函数将创建指定窗口的线程设置到前台，并且激活该窗口。键盘输入转向该窗口，并为用户改各种可视的记号。系统给创建前台窗口的线程分配的权限稍高于其他线程。         /// </summary>         /// <param name="hWnd">将被激活并被调入前台的窗口句柄。</param>         /// <returns>如果窗口设入了前台，返回值为非零；如果窗口未被设入前台，返回值为零。</returns>         [DllImport("User32.dll")]        private static extern bool SetForegroundWindow(IntPtr hWnd);        private const int WS_SHOWNORMAL = 1;               /// <summary>        /// 应用程序的主入口点。        /// </summary>        [STAThread]        static void Main()        {            Application.EnableVisualStyles();            Application.SetCompatibleTextRenderingDefault(false);            Process instance = RunningInstance();            if (instance == null)            {                Form1 frm = new Form1();                Application.Run(new Form1());            }            else            {                HandleRunningInstance(instance);            }         }        public static Process RunningInstance()        {            Process current = Process.GetCurrentProcess();            Process[] processes = Process.GetProcessesByName(current.ProcessName);            foreach (Process process in processes)            {                if (process.Id != current.Id)                {                    if (Assembly.GetExecutingAssembly().Location.Replace("/", "//") == current.MainModule.FileName)                    {                        return process;                    }                }            }            return null;        }        /// <summary>         /// 显示已运行的程序。         /// </summary>         public static void HandleRunningInstance(Process instance)        {            ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL); //显示，可以注释掉             SetForegroundWindow(instance.MainWindowHandle);            //放到前端         }     }}