C#程序单例模式运行

static class Program
{
///
/// 应用程序的主入口点。
///
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
bool ret;
Mutex mutex = new Mutex(true, “FormMain”, out ret);
//Application.ProductName
if (ret)
{
Application.Run(new FormMain());
}
else
{
var current = Process.GetCurrentProcess();

            foreach (var process in Process.GetProcessesByName(current.ProcessName))
            {
                if (process.Id != current.Id)
                {
                   SetForegroundWindow(process.MainWindowHandle);
                    break;
                }
            }
           // Shutdown();
        }
       

    }


    [DllImport("user32.dll", EntryPoint = "SetForegroundWindow", SetLastError = true)]
    public static extern void SetForegroundWindow(IntPtr hwnd);  //已经运行的程序放到前台
}