[STAThread]

        static void Main()

        {

            Application.EnableVisualStyles();

            Application.SetCompatibleTextRenderingDefault(false);

   

        System.Threading.Mutex mutex = new System.Threading.Mutex(false, "SINGLE_INSTANCE_MUTEX");

            if (!mutex.WaitOne(0, false))

            {

                mutex.Close();

                mutex = null;

            }

            if (mutex != null)

            {

                Application.Run(new Form1());

            }

            else

            {

                MessageBox.Show("程序已经启动 ");

            }

        }