这里有一个解决方案:

Protected Overrides Sub OnStartup(e As StartupEventArgs)
    Const appName As String = "TestApp"
    Dim createdNew As Boolean
    _mutex = New Mutex(True, appName, createdNew)
    If Not createdNew Then
        'app is already running! Exiting the application
        MessageBox.Show("Application is already running.")
        Application.Current.Shutdown()
    End If
    MyBase.OnStartup(e)
End Sub

从这里。

跨进程互斥锁的一个常见用途是确保一个程序一次只能运行一个实例。以下是如何做到的:

class OneAtATimePlease {

  // Use a name unique to the application (eg include your company URL)
  static Mutex mutex = new Mutex (false, "oreilly.com OneAtATimeDemo");

  static void Main()
  {
    // Wait 5 seconds if contended – in case another instance
    // of the program is in the process of shutting down.
    if (!mutex.WaitOne(TimeSpan.FromSeconds (5), false))
    {
        Console.WriteLine("Another instance of the app is running. Bye!");
        return;
    }

    try
    {    
        Console.WriteLine("Running - press Enter to exit");
        Console.ReadLine();
    }
    finally
    {
        mutex.ReleaseMutex();
    }    
  }    
}

互斥锁的一个很好的特性是，如果应用程序在没有首先调用ReleaseMutex的情况下终止，CLR将自动释放互斥锁。

我在解决方案中使用互斥来防止多个实例。

static Mutex mutex = null;
//A string that is the name of the mutex
string mutexName = @"Global\test";
//Prevent Multiple Instances of Application
bool onlyInstance = false;
mutex = new Mutex(true, mutexName, out onlyInstance);

if (!onlyInstance)
{
  MessageBox.Show("You are already running this application in your system.", "Already Running..", MessageBoxButton.OK);
  Application.Current.Shutdown();
}

我添加了一个sendMessage方法到NativeMethods类。

显然，如果应用程序没有显示在任务栏中，postmessage方法不会工作，但是使用sendmessage方法解决了这个问题。

class NativeMethods
{
    public const int HWND_BROADCAST = 0xffff;
    public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME");
    [DllImport("user32")]
    public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    public static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
    [DllImport("user32")]
    public static extern int RegisterWindowMessage(string message);
}

这里有一个解决方案:

Protected Overrides Sub OnStartup(e As StartupEventArgs)
    Const appName As String = "TestApp"
    Dim createdNew As Boolean
    _mutex = New Mutex(True, appName, createdNew)
    If Not createdNew Then
        'app is already running! Exiting the application
        MessageBox.Show("Application is already running.")
        Application.Current.Shutdown()
    End If
    MyBase.OnStartup(e)
End Sub

这么简单的问题有这么多答案。稍微改变一下这里是我对这个问题的解决方案。

Creating a Mutex can be troublesome because the JIT-er only sees you using it for a small portion of your code and wants to mark it as ready for garbage collection. It pretty much wants to out-smart you thinking you are not going to be using that Mutex for that long. In reality you want to hang onto this Mutex for as long as your application is running. The best way to tell the garbage collector to leave you Mutex alone is to tell it to keep it alive though out the different generations of garage collection. Example:

var m = new Mutex(...);
...
GC.KeepAlive(m);

我从这个网页上获得了灵感:http://www.ai.uga.edu/~mc/SingleInstance.html