Make windows applications have only one instance

Using system;
Using system. diagnostics;
Using system. Windows. forms;
Using system. reflection;
Using system. runtime. interopservices;

Using zhzuo. wingui;

Namespace zhzuo
{
/** // <Summary>
/// Summary of appstart.
/// </Summary>
Public class applicationstart
{
Private const int ws_shownormal = 1;
[Dllimport ("user32.dll")]
Private Static extern bool showwindowasync (intptr hwnd, int cmdshow );
[Dllimport ("user32.dll")]
Private Static extern bool setforegroundwindow (intptr hwnd );

/** // <Summary>
/// Main entry point of the application.
/// </Summary>
[STAThread]
Static void Main ()
{
Process instance = GetRunningInstance ();
If (instance = null)
{
// Initialize the program Configuration
// ApplicationSettings. Initialize ();
Application. Run (new MainForm ());
}
Else
{
HandleRunningInstance (instance );
}
}
/** // <Summary>
/// Obtain the application instance. If no other routine exists, Null is returned.
/// </Summary>
/// <Returns> </returns>
Public static Process GetRunningInstance ()
{
Process current = Process. GetCurrentProcess ();
Process [] processes = Process. GetProcessesByName (current. ProcessName );
// Traverse a routine with the same name running
Foreach (Process process in processes)
{
// Ignore existing routines
If (process. Id! = Current. Id)
// Ensure that the routine runs from the EXE file
If (Assembly. GetExecutingAssembly (). Location. Replace ("/", "\") = current. MainModule. FileName)
// Return another routine instance
Return process;
}
Return null;
}
/** // <Summary>
/// Obtain the window handle
/// </Summary>
/// <Param name = "instance"> </param>
Public static void HandleRunningInstance (Process instance)
{
// Ensure that the window is not minimized or maximized
ShowWindowAsync (instance. main1_whandle, WS_SHOWNORMAL );
// Set the actual routine to foreground window
SetForegroundWindow (instance. main1_whandle );
}
}
}