通常，这是我用于单实例Windows窗体应用程序的代码:

[STAThread]
public static void Main()
{
    String assemblyName = Assembly.GetExecutingAssembly().GetName().Name;

    using (Mutex mutex = new Mutex(false, assemblyName))
    {
        if (!mutex.WaitOne(0, false))
        {
            Boolean shownProcess = false;
            Process currentProcess = Process.GetCurrentProcess();

            foreach (Process process in Process.GetProcessesByName(currentProcess.ProcessName))
            {
                if (!process.Id.Equals(currentProcess.Id) && process.MainModule.FileName.Equals(currentProcess.MainModule.FileName) && !process.MainWindowHandle.Equals(IntPtr.Zero))
                {
                    IntPtr windowHandle = process.MainWindowHandle;

                    if (NativeMethods.IsIconic(windowHandle))
                        NativeMethods.ShowWindow(windowHandle, ShowWindowCommand.Restore);

                    NativeMethods.SetForegroundWindow(windowHandle);

                    shownProcess = true;
                }
            }

            if (!shownProcess)
                MessageBox.Show(String.Format(CultureInfo.CurrentCulture, "An instance of {0} is already running!", assemblyName), assemblyName, MessageBoxButtons.OK, MessageBoxIcon.Asterisk, MessageBoxDefaultButton.Button1, (MessageBoxOptions)0);
        }
        else
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form());
        }
    }
}

本地组件的位置:

[DllImport("User32.dll", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern Boolean IsIconic([In] IntPtr windowHandle);

[DllImport("User32.dll", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern Boolean SetForegroundWindow([In] IntPtr windowHandle);

[DllImport("User32.dll", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern Boolean ShowWindow([In] IntPtr windowHandle, [In] ShowWindowCommand command);

public enum ShowWindowCommand : int
{
    Hide                   = 0x0,
    ShowNormal             = 0x1,
    ShowMinimized          = 0x2,
    ShowMaximized          = 0x3,
    ShowNormalNotActive    = 0x4,
    Minimize               = 0x6,
    ShowMinimizedNotActive = 0x7,
    ShowCurrentNotActive   = 0x8,
    Restore                = 0x9,
    ShowDefault            = 0xA,
    ForceMinimize          = 0xB
}

Just some thoughts: There are cases when requiring that only one instance of an application is not "lame" as some would have you believe. Database apps, etc. are an order of magnitude more difficult if one allows multiple instances of the app for a single user to access a database (you know, all that updating all the records that are open in multiple instances of the app on the users machine, etc.). First, for the "name collision thing, don't use a human readable name - use a GUID instead or, even better a GUID + the human readable name. Chances of name collision just dropped off the radar and the Mutex doesn't care. As someone pointed out, a DOS attack would suck, but if the malicious person has gone to the trouble of getting the mutex name and incorporating it into their app, you are pretty much a target anyway and will have to do MUCH more to protect yourself than just fiddle a mutex name. Also, if one uses the variant of: new Mutex(true, "some GUID plus Name", out AIsFirstInstance), you already have your indicator as to whether or not the Mutex is the first instance.

看起来有一个很好的方法来处理这个问题:

WPF单实例应用程序

这提供了一个类，您可以添加它来管理所有互斥量和消息传递的cruff，从而将实现简化到非常简单的程度。

请检查这里提出的解决方案，它使用信号量来确定现有实例是否已经在运行，适用于WPF应用程序，并且可以通过使用TcpListener和TcpClient将参数从第二个实例传递给第一个已经运行的实例:

它不仅适用于。net Framework，也适用于。net Core。

这是我用的。它结合了进程枚举来执行切换和互斥，以防止“活动点击器”:

public partial class App
{
    [DllImport("user32")]
    private static extern int OpenIcon(IntPtr hWnd);

    [DllImport("user32.dll")]
    private static extern bool SetForegroundWindow(IntPtr hWnd);

    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);
        var p = Process
           .GetProcessesByName(Process.GetCurrentProcess().ProcessName);
            foreach (var t in p.Where(t => t.MainWindowHandle != IntPtr.Zero))
            {
                OpenIcon(t.MainWindowHandle);
                SetForegroundWindow(t.MainWindowHandle);
                Current.Shutdown();
                return;
            }

            // there is a chance the user tries to click on the icon repeatedly
            // and the process cannot be discovered yet
            bool createdNew;
            var mutex = new Mutex(true, "MyAwesomeApp", 
               out createdNew);  // must be a variable, though it is unused - 
            // we just need a bit of time until the process shows up
            if (!createdNew)
            {
                Current.Shutdown();
                return;
            }

            new Bootstrapper().Run();
        }
    }

永远不要使用命名互斥来实现单实例应用程序(至少在生产代码中不要这样做)。恶意代码可以很容易地DoS(拒绝服务)你的屁股…