【转】winform 程序实现一次只能打开一个该程序

ref： http://www.jb51.net/article/17747.htm

//在程序的main函数中加入以下代码 
bool createdNew; 
System.Threading.Mutex instance = new System.Threading.Mutex(true, "MutexName", out createdNew); 
if (createdNew) 
{ 
　　Application.Run(new LoginForm()); 
　　instance.ReleaseMutex(); 
} 
else 
{ 
　　Application.Exit(); 
} 
//还可以写成以下形式，一个窗体只能启动一次 
Form1 a = new Form1(); 
bool createdNew; 
System.Threading.Mutex instance = new System.Threading.Mutex(true, "MutexName", out createdNew); 
if (createdNew) 
{ 
　　a.ShowDialog(); 
　　instance.ReleaseMutex(); 
} 
else 
{ 
　　a.Close(); 
}

private static bool HasRunning()
{
    Process currentProcess = Process.GetCurrentProcess();
    Process[] processCollection = Process.GetProcessesByName(currentProcess.ProcessName);
    foreach (Process p in processCollection)
    {
        if (p.Id == currentProcess.Id)  //检查ID是否相同
        {
            return true;
        }
    }
    return false;
}