Winform只运行一个实例

创建帮助类

单例帮助类

 public class MainHelper
    {
        public static Process RunningInstance(string location)
        {
            var current = Process.GetCurrentProcess();
            var processes = Process.GetProcessesByName(current.ProcessName);
            foreach (Process process in processes)
            {
                if (process.Id != current.Id)
                {
                    if (location.Replace("/", @"\") == current.MainModule.FileName)
                    {
                        return process;
                    }
                }
            }
            return null;
        }

        public static void Active(Process instance)
        {
            ShowWindowAsync(instance.MainWindowHandle, 1);
            SetForegroundWindow(instance.MainWindowHandle);
        }

        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);

        [DllImport("User32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);
    }

 

// ShowWindowAsync      说明
private const int SW_HIDE = 0;

private const int SW_NORMAL = 1;

private const int SW_MAXIMIZE = 3;

private const int SW_SHOWNOACTIVATE = 4;

private const int SW_SHOW = 5;

private const int SW_MINIMIZE = 6;

private const int SW_RESTORE = 9;

private const int SW_SHOWDEFAULT = 10;

调用

var location = Assembly.GetExecutingAssembly().Location;
 var instance = MainHelper.RunningInstance(location);
 if (instance != null)
 {
     MainHelper.Active(instance);
 }
 else
 {
     Application.Run(new Form());
 }