C#如何讓應用程序只有一個實例在運行

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Diagnostics;
using System.Reflection;

public class OneInstnace
{
[STAThread]
public static void Main()
{
//得到正在運行的例程
Process instance = RunningInstance();
if (instance == null)
{
//如果沒有其它例程，就新建一個窗體
Application.Run (new Form());
}
else
{
//處理發現的例程
HandleRunningInstance(instance);
}
}
public static Process RunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);

//遍歷正在有相同名字運行的例程
foreach (Process process in processes)
{
//忽略現有的例程
if (process.Id != current.Id)
{
//確保例程從EXE文件運行
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") ==current.MainModule.FileName)
{
//返回另一個例程實例
return process;
}
}
}

//沒有其它的例程，返回Null
return null;
}

public static void HandleRunningInstance(Process instance)
{
//確保窗口沒有被最小化或最大化
ShowWindowAsync (instance.MainWindowHandle , WS_SHOWNORMAL);

//設置真實例程為foreground window
SetForegroundWindow (instance.MainWindowHandle);
}

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

[DllImport("User32.dll")]
private static extern bool SetForegroundWindow(IntPtr hWnd);
private const int WS_SHOWNORMAL = 1;
}