C#winfrom中应用程序只启动一次代码

static class Program
{
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>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Process instance = GetRunningInstance();
if (instance==null)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Login());
}
else
{
HandleRunningInstance(instance);

}
}

public static Process GetRunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName(current.ProcessName);
//遍历正在有相同名字运行的例程
foreach (Process process in processes)
{
//忽略现有的例程
if (process.Id != current.Id)
//确保例程从EXE文件运行
if ( System.Reflection.Assembly.GetExecutingAssembly().Location.Replace("/" , "\\") == current.MainModule.FileName )
return process;
}
return null;
}
/// <summary>
/// 激活原有的进程。
/// </summary>
/// <param name="instance"></param>
public static void HandleRunningInstance(Process instance)
{
ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL);
SetForegroundWindow(instance.MainWindowHandle);
}
}

看了评论，学习了新的方法。

void Mian()

{

bool isStart;
Mutex MyMutex = new Mutex(true, "RunOne", out isStart);
if (isStart)
{
启动程序
Application.Run(new Form());
}
else{
//程序已经启动
}

}