模式屏幕锁

近日在贾涛老师的BLOG上,看到了一偏文章主要是回答CSDN上朋友提出的问题:
"当我登录进入主界面时，在规定的时间内没有做任何操作，系统就注销（就像电脑的屏保）。 "
http://blog.csdn.net/jinjazz/archive/2008/02/21/2110620.aspx
看了代码后根据实际的需要做了如下的修改:
1:需要导入非托管DLL"user32"
在Class写下如是代码:
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Runtime.InteropServices;

 public class OnNotOperation : System.Windows.Forms.Form
 {
  [StructLayout(LayoutKind.Sequential)]
   public struct LASTINPUTINFO
  {
   [MarshalAs(UnmanagedType.U4)]
    public int cbSize;
   [MarshalAs(UnmanagedType.U4)]
    public uint dtTime;
  }

//调用获取最后一次操作屏幕的时间(包括鼠标移动,键盘等)
  [DllImport("user32")]
   public static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);
  public long getIdleTick()
  {
   LASTINPUTINFO i = new LASTINPUTINFO();
   i.cbSize = Marshal.SizeOf(i);
   if(!GetLastInputInfo(ref i)) return 0;
   return Environment.TickCount -(long)i.dtTime;
  }
//导入user32调用屏保的API
  [DllImport("user32")]
//屏保的API
   public static extern int SendMessageA(int hWnd, int Msg, int wParam, int lParam);
  private const int HWND_BROADCAST = 0xffff;
  private const int WM_SYSCOMMAND = 0x112;
  private const int SC_SCREENSAVE = 0xf140;
//自定义产生屏保的方法
  public void  screenSaveStart()
  {
   SendMessageA(HWND_BROADCAST, WM_SYSCOMMAND, SC_SCREENSAVE, 0);
  }
//导入user32并调用锁屏的API
  [DllImport("user32")]
   public static extern bool LockWorkStation();
//自定义的锁屏方法
  private void LockWindow()
  {
   bool retuen =  LockWorkStation();
   if(retuen == false)
   {
    throw new Win32Exception(Marshal.GetLastWin32Error());
   }
  }

private void OnNotOperation_Load(object sender, System.EventArgs e)
  {
//开始TIMER的运行
   this.timer1.Interval=2000;
   this.timer1.Enabled =true;
  }

  private void timer1_Tick(object sender, System.EventArgs e)
  {
   long i = getIdleTick();
   this.label1.Text = String.Format("zyzhang,你已經{0}ms沒有動電腦了",i);
//20秒内如果没有动作就锁定屏幕
   if(i>2*1000)
   {
    //this.WindowState = FormWindowState.Minimized;
//屏幕锁定
    LockWindow();
//停止TIMER的运行
    this.timer1.Enabled=false;
//出现屏保的效果
    //screenSaveStart();
   }
   else
   {
    this.WindowState =FormWindowState.Normal;
   }
  }
}