保证应用程序只有一个实例运行

         public static Process RunningInstance()
        {
            Process current = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName(current.ProcessName);
            //查找相同名称的进程
            foreach (Process process in processes)
            {
                //忽略当前进程
                if (process.Id != current.Id)
                {
                    //确认相同进程的程序运行位置是否一样.
                    if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
                    {
                        //Return the other process instance.
                        return process;
                    }
                }
            }
            //No other instance was found, return null.
            return null;
        }