屏幕锁定程序例子

导入win32api程序

using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
using System.Runtime.InteropServices;

namespace ScreenLock
{
    class Win32Api
    {
        
    
        //设置钩子
        [DllImport("user32.dll")]
        public static extern int SetWindowsHookEx(int idHook,HookProc lpfn,IntPtr hInstance,int threadID);
        //卸载钩子
        [DllImport("user32.dll,CharSet=CharSet.Auto,CallingConvention=CallingConvention.StdCall")]
        public static extern bool UnHookWindowsHookEx(int idHook);
        //调用下一个钩子
        [DllImport("user32.dll")]
        public static extern int CallNextHookEx(int idHook, int nCode,int wParam,IntPtr lParam);
        //返回当前线程ID值
        [DllImport("kernel32.dll")]
        public static extern int GetCurrentThreadId();

        //返回指定模块的句柄
        [DllImport("kernel32.dll")]
        public static extern IntPtr GetModuleHandle(string name);
    }
}

程序锁定模块

using System;
using System.Windows.Forms;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace ScreenLock
{
    public delegate int HookProc(int nCode, int wParam, IntPtr lParam);//定义钩子过程委托（钩子函数原型)
    public partial class LockForm : Form
    {
       
        public LockForm()
        {
            InitializeComponent();
            HookStart();//启动Hook，截获键盘事件
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //密码正确，将将窗体以淡出形式退出
                ControlOpacity.Enabled = true;
                
        }


        //下面定义键盘钩子的相关内容，用于截获键盘消息
        #region
        HookProc KeyBoardProcedure;

        static int hHook = 0;//钩子函数的句柄

        public const int WH_KEYBOARD = 13;



        //钩子结构函数
        public struct KeyBoardHookStruct
        {
            public int vkCode;
            public int scanCode;
            public int flags;
            public int time;
            public int dwExtraInfo;

        }



        //安装键盘钩子
        public void HookStart()
        {
            if (hHook == 0)
            {
                //实例化一个HookProc对象
                KeyBoardProcedure = new HookProc(LockForm.KeyBoardHookProc);

                //创建线程钩子
                hHook = Win32Api.SetWindowsHookEx(WH_KEYBOARD, KeyBoardProcedure, Win32Api.GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName), 0);

                //如果设置线程钩子失败
                if (hHook == 0)
                {
                    HookClear();
                }
            }
        }

        //取消钩子
        public void HookClear()
        {
            bool rsetKeyboard = true;
            if (hHook != 0)
            {
                rsetKeyboard = Win32Api.UnHookWindowsHookEx(hHook);
                hHook = 0;
            }
            if (!rsetKeyboard)
            {
                throw new Exception("取消钩子失败!");
            }
        }

        //对截获的键盘操作的处理
        public static int KeyBoardHookProc(int nCode, int wParam, IntPtr lParam)
        {
            if (nCode >= 0)
            {
                KeyBoardHookStruct kbh = (KeyBoardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyBoardHookStruct));

                if (kbh.vkCode == 91)//截获左边WIN键
                {
                    return 1;
                }
                if (kbh.vkCode == 92)//截获右边WIN键
                {
                    return 1;
                }
                if (kbh.vkCode == (int)Keys.Escape && (int)Control.ModifierKeys == (int)Keys.Control)//截获Ctrl+ESC键
                {
                    return 1;
                }
                if (kbh.vkCode == (int)Keys.F4 && (int)Control.ModifierKeys == (int)Keys.Alt)//截获ALT+F4
                {
                    return 1;
                }
                if (kbh.vkCode == (int)Keys.Tab && (int)Control.ModifierKeys == (int)Keys.Alt)//截获ALT+TAB
                {
                    return 1;
                }
                //......可以在这里做更多处理

            }

            return Win32Api.CallNextHookEx(hHook, nCode, wParam, lParam);
        }

        #endregion


        //控制窗体透明度
        private void ControlOpacity_Tick_1(object sender, EventArgs e)
        {
            if (this.Opacity <= 0.1)
            {
                this.Close();
            }
            else
            {
                this.Opacity = this.Opacity - 0.1;
            }
        }

        private void KillTaskmgr_Tick(object sender, EventArgs e)
        {
            Process[] remoteAll = Process.GetProcessesByName("taskmgr");
            foreach (Process  s in remoteAll )
            {
                s.Kill();
            }
        }

      
       
    }
}