在c#中怎么调用ExitWindowsEx函数实现XP的关机、注销、重启操作？

-----------代码范例------------------

using System;

using System.Collections.Generic;

using System.Text;





namespace System.Helper

{

 

    public class ServerRoot

    {

        [StructLayout(LayoutKind.Sequential, Pack = 1)]

        internal struct TokPriv1Luid

        {

            public int Count;

            public long Luid;

            public int Attr;

        }

        [DllImport("kernel32.dll", ExactSpelling = true)]

        internal static extern IntPtr GetCurrentProcess();



        [DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]

        internal static extern bool OpenProcessToken(IntPtr h, int acc, ref IntPtr phtok);



        [DllImport("advapi32.dll", SetLastError = true)]

        internal static extern bool LookupPrivilegeValue(string host, string name, ref long pluid);



        [DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]

        internal static extern bool AdjustTokenPrivileges(IntPtr htok, bool disall,

            ref TokPriv1Luid newst, int len, IntPtr prev, IntPtr relen);



        [DllImport("user32.dll", ExactSpelling = true, SetLastError = true)]

        internal static extern bool ExitWindowsEx(int DoFlag, int rea);



        internal const int SE_PRIVILEGE_ENABLED = 0x00000002;

        internal const int TOKEN_QUERY = 0x00000008;

        internal const int TOKEN_ADJUST_PRIVILEGES = 0x00000020;

        internal const string SE_SHUTDOWN_NAME = "SeShutdownPrivilege";

        internal const int EWX_LOGOFF = 0x00000000;

        internal const int EWX_SHUTDOWN = 0x00000001;

        internal const int EWX_REBOOT = 0x00000002;

        internal const int EWX_FORCE = 0x00000004;

        internal const int EWX_POWEROFF = 0x00000008;

        internal const int EWX_FORCEIFHUNG = 0x00000010;



        private static bool DoExitWin(int DoFlag)

        {

            bool ok;

            TokPriv1Luid tp;

            IntPtr hproc = GetCurrentProcess();

            IntPtr htok = IntPtr.Zero;

            ok = OpenProcessToken(hproc, TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, ref htok);

            tp.Count = 1;

            tp.Luid = 0;

            tp.Attr = SE_PRIVILEGE_ENABLED;

            ok = LookupPrivilegeValue(null, SE_SHUTDOWN_NAME, ref tp.Luid);

            ok = AdjustTokenPrivileges(htok, false, ref tp, 0, IntPtr.Zero, IntPtr.Zero);

            ok = ExitWindowsEx(DoFlag, 0);

            return ok;

        }



        /**/

        /// <summary>

        /// 重新启动

        /// </summary>

        public static bool Reboot()

        {

            return DoExitWin(EWX_FORCE | EWX_REBOOT);

        }



        /**/

        /// <summary>

        /// 关机

        /// </summary>

        public static bool PowerOff()

        {

            return DoExitWin(EWX_FORCE | EWX_POWEROFF);

        }



        /**/

        /// <summary>

        /// 注销

        /// </summary>

        public static bool LogOff()

        {

            return DoExitWin(EWX_FORCE | EWX_LOGOFF);

        }

    }

}