c# 程序只能运行一个实例

程序只能运行一个程序
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Diagnostics;
using System.Reflection;

namespace SystemTray
{
static class Program
{
/// <summary>
/// 應用程式的主入口點。
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Process instance = RunningInstance();
if (instance == null)
{
//如果沒有其他常式，就新建一個表單
//Application.Run(new Form());
Application.Run(new ClockWaring());
}
else
{
//處理發現的常式
HandleRunningInstance(instance);
}
}

public static Process RunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);

//遍曆正在有相同名字運行的常式
foreach (Process process in processes)
{
//忽略現有的常式
if (process.Id != current.Id)
{
//確保常式從EXE檔運行
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") ==
current.MainModule.FileName)
{
//返回另一個常式實例
return process;
}
}
}

//沒有其他的常式，返回Null
return null;
}

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

//設置真實常式為foreground window
SetForegroundWindow(instance.MainWindowHandle);
}

[DllImport("User32.dll")]

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

}
}