winfrom判断程序是否运行，并给提示

private static System.Threading.Mutex mutex;
/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
mutex = new System.Threading.Mutex(true, "TcpSocket");
if (mutex.WaitOne(0, false))
{
Application.Run(new Form1());
}
else
{
MessageBox.Show("程序已经在运行！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
Application.Exit();
}
}