有时在应用中需要获取当前的系统状态，如果闲置一段时间将锁屏或自动登出。

代码示例

internal struct LASTINPUTINFO
        {
            public uint cbSize;
            public uint dwTime;
        }

        [DllImport("User32.dll")]
        public static extern bool LockWorkStation();
        [DllImport("User32.dll")]
        private static extern bool GetLastInputInfo(ref LASTINPUTINFO Dummy);
        [DllImport("Kernel32.dll")]
        private static extern uint GetLastError();

        public static uint GetIdleTime()
        {
            LASTINPUTINFO LastUserAction = new LASTINPUTINFO();
            LastUserAction.cbSize = (uint)Marshal.SizeOf(LastUserAction);
            GetLastInputInfo(ref LastUserAction);
            return ((uint)Environment.TickCount - LastUserAction.dwTime);
        }

        public static long GetTickCount()
        {
            return Environment.TickCount;
        }

        public static long GetLastInputTime()
        {
            LASTINPUTINFO LastUserAction = new LASTINPUTINFO();
            LastUserAction.cbSize = (uint)Marshal.SizeOf(LastUserAction);
            if (!GetLastInputInfo(ref LastUserAction))
            {
                throw new Exception(GetLastError().ToString());
            }

            return LastUserAction.dwTime;
        }

可以调用GetIdleTime()方法，返回的是毫秒。