There are several option that can be used to create singleton application.
Option 1.
///
<summary>
/// Supporting function for “singleton” functionality
///
</summary>
///
<returns></returns>
public
static
Process IsRunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);
//Loop through the running processes in with the same name
foreach (Process process in processes)
{
//Ignore the current process
if (process.Id != current.Id)
{
//Make sure that the process is running from the exe file.
if (Assembly.GetExecutingAssembly().Location.
Replace(“/”, “\\”) == current.MainModule.FileName)
{
//Return the other process instance.
return process;
}
}
}
//No other instance was found, return null.
return
null;
}
Application code (in constructor of the main form):
// Singleton verification – exit if application is already started
if (RunningInstance() != null)
{
string singletonRedirectUrl = util.GetAppSetting(“singletonRedirectUrl”, “0”);
string redirectPage = DownloadWebPage(singletonRedirectUrl);
//MessageBox.Show(“redirected”);
log.Info(“Duplicate instance detected. Exiting application.”);
System.Environment.Exit(1);
}
Option 2.
This sample is based on:
http://blog.billsdon.com/2011/10/c-sharp-check-if-application-is-already-running-then-set-focus/
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
/// ————————————————————————————————-
/// <summary> Application Running Helper. </summary>
/// ————————————————————————————————-
public static class ApplicationRunningHelper
{
[DllImport(“user32.dll”)]
private static extern
bool SetForegroundWindow(IntPtr hWnd);
[DllImport(“user32.dll”)]
private static extern
bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);
[DllImport(“user32.dll”)]
private static extern
bool IsIconic(IntPtr hWnd);
/// ————————————————————————————————-
/// <summary> check if current process already running. if running, set focus to existing process and
/// returns <see langword=”true”/> otherwise returns <see langword=”false”/>. </summary>
/// <returns> <see langword=”true”/> if it succeeds, <see langword=”false”/> if it fails. </returns>
/// ————————————————————————————————-
public static bool AlreadyRunning()
{
/*
const int SW_HIDE = 0;
const int SW_SHOWNORMAL = 1;
const int SW_SHOWMINIMIZED = 2;
const int SW_SHOWMAXIMIZED = 3;
const int SW_SHOWNOACTIVATE = 4;
const int SW_RESTORE = 9;
const int SW_SHOWDEFAULT = 10;
*/
const int swRestore = 9;
var me = Process.GetCurrentProcess();
var arrProcesses = Process.GetProcessesByName(me.ProcessName);
if (arrProcesses.Length > 1)
{
for (var i = 0; i < arrProcesses.Length; i++)
{
if (arrProcesses[i].Id != me.Id)
{
// get the window handle
IntPtr hWnd = arrProcesses[i].MainWindowHandle;
// if iconic, we need to restore the window
if (IsIconic(hWnd))
{
ShowWindowAsync(hWnd, swRestore);
}
// bring it to the foreground
SetForegroundWindow(hWnd);
break;
}
}
return true;
}
return false;
}
}
