防止程序被多次实例运行

[STAThread]
static void Main()
{
System.Diagnostics.Process[] ps = System.Diagnostics.Process.GetProcessesByName(System.Diagnostics.Process.GetCurrentProcess().ProcessName);
if (ps.Length <= 1)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}