如何使应用程序只有一个实例在运行

[STAThread]
    static void Main()                  // args are OK here, of course
    {
        bool ok;
        m = new System.Threading.Mutex(true, "YourNameHere", out ok);

        if (! ok)
        {
            MessageBox.Show("Another instance is already running.");
            return;
        }

        Application.Run(new Form1());   // or whatever was there

        GC.KeepAlive(m);                // important!
    }