//方法一：只禁止多个进程运行using System;using System.Collections.Generic;using System.Windows.Forms;namespace DuoYeMianIE{    static class Program    {        /// <summary>        /// 应用程序的主入口点。        /// </summary>        [STAThread]        static void Main()        {            bool ret;            System.Threading.Mutex mutex = new System.Threading.Mutex(true, Application.ProductName, out ret);            if (ret)            {                System.Windows.Forms.Application.EnableVisualStyles();   //这两行实现   XP   可视风格                   System.Windows.Forms.Application.DoEvents();             //这两行实现   XP   可视风格                   System.Windows.Forms.Application.Run(new LamBrowser());                //   Main   为你程序的主窗体，如果是控制台程序不用这句                   mutex.ReleaseMutex();            }            else            {                MessageBox.Show(null, "有一个和本程序相同的应用程序已经在运行，请不要同时运行多个本程序。\n\n这个程序即将退出。", Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Warning);                //   提示信息，可以删除。                   Application.Exit();//退出程序               }        }    }}

//方法二：禁止多个进程运行,并当重复运行时激活以前的进程using System;using System.Collections.Generic;using System.Windows.Forms;using System.Diagnostics;using System.Runtime.InteropServices;using System.Reflection;namespace DuoYeMianIE{    static class Program    {        /// <summary>        /// 应用程序的主入口点。        /// </summary>        [STAThread]        static void Main(){    //Get   the   running   instance.       Process instance = RunningInstance();    if (instance == null)    { System.Windows.Forms.Application.EnableVisualStyles();   //这两行实现   XP   可视风格           System.Windows.Forms.Application.DoEvents();        //There   isn‘t   another   instance,   show   our   form.           System.Windows.Forms.Application.Run(new LamBrowser());    }        else    {        //There   is   another   instance   of   this   process.           HandleRunningInstance(instance);    }}   public static Process RunningInstance(){        Process current = Process.GetCurrentProcess();    Process[] processes = Process.GetProcessesByName(current.ProcessName);    //Loop   through   the   running   processes   in   with   the   same   name       foreach (Process process in processes)    {        //Ignore   the   current   process           if (process.Id != current.Id)        {            //Make   sure   that   the   process   is   running   from   the   exe   file.                          if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)            {                //Return   the   other   process   instance.                   return process;            }        }    }    //No   other   instance   was   found,   return   null.     return null;}public static void HandleRunningInstance(Process instance){    //Make   sure   the   window   is   not   minimized   or   maximized       ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL);    //Set   the   real   intance   to   foreground   window    SetForegroundWindow(instance.MainWindowHandle);}[DllImport("User32.dll")]private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);[DllImport("User32.dll")]private static extern bool SetForegroundWindow(IntPtr hWnd);private const int WS_SHOWNORMAL = 1;    }}