public class Constrctor

    {

        public Constrctor()

        {

            SystemEvents.SessionSwitch += new SessionSwitchEventHandler(SystemEvents_SessionSwitch);

        }

        ~Constrctor()

        {

            Microsoft.Win32.SystemEvents.SessionSwitch -= new SessionSwitchEventHandler(SystemEvents_SessionSwitch);

        }

        void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)

        {

            switch (e.Reason)

            {

                case SessionSwitchReason.SessionLogon:

                    Console.WriteLine("用户登录");

                    break;

                case SessionSwitchReason.SessionUnlock:

                    Console.WriteLine("解锁");

                    break;

                case SessionSwitchReason.SessionLock:

                    Console.WriteLine("锁屏");

                    break;

                case SessionSwitchReason.SessionLogoff:

                    Console.WriteLine("注销");

                    break;

            }

        }

    }