AppJustOne.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Windows;
namespace FLY.AppHelper
{
    public class AppJustOne
    {
        public  AppJustOne(Application app) 
        {
            app.Startup += new StartupEventHandler(app_Startup);

        }

        void app_Startup(object sender, StartupEventArgs e)
        {
            Process process = Process.GetCurrentProcess();
            string name = process.ProcessName;

            Process[] processes = Process.GetProcesses();
            IEnumerable<Process> ps = from p in processes
                                      where
                                          (p.ProcessName == process.ProcessName) &&
                                          (p.Id != process.Id) &&
                                          (p.MainModule.FileName == process.MainModule.FileName) &&
                                          (!p.HasExited)
                                      select p;
            try
            {
                if (ps.Count() >= 1)
                {
                    MessageBoxResult r = MessageBox.Show(name + "已经运行， 是否关闭正在运行的，然后重启新的？", "警告", MessageBoxButton.YesNo, MessageBoxImage.Warning, MessageBoxResult.No);
                    if (r == MessageBoxResult.Yes)
                    {
                    
                            for (int i = 0; i < ps.Count(); i++)
                            {
                                Process p = ps.ElementAt(i);
                                p.Kill();
                            }

                    }
                    else
                    {
                        System.Environment.Exit(0);
                    }
                }
            }
            catch
            {
                //当有进程正在关闭时，访问ps 就会出错
            }
        }
    }
}