C# .NET锁屏程序（顺带屏蔽任务管理器）

第一步：将窗体的FormBorderStyle设置为none，WindowState设为Maximized

占据整个屏幕。

第二步：使用钩子监控全局键盘事件。即屏蔽掉大部分系统热键。但是屏蔽ctrl+alt+del 任务管理器则较复杂，这个特例后面讨论。

使用全局钩子应该注意的地方：将代码放到一个独立的类库里面（只有dll才能被注射到其他进程中）。

using System; 

using System.Collections.Generic; 

using System.Text; 

using System.Runtime.InteropServices; 

using System.IO; 

using System.Reflection; 

namespace KeyboardHookDLL 

{ 

    public class KeyboardHook 

    { 

        public delegate int KeyboardProc(int nCode, IntPtr wParam, IntPtr lParam); 

        static int hKeyboardHook = 0; 

        KeyboardProc KeyboardHookProcedure; 

        /// <summary> 

        /// 钩子函数,需要引用空间(using System.Reflection;) 

        /// 线程钩子监听键盘消息设为2,全局钩子监听键盘消息设为13 

        /// 线程钩子监听鼠标消息设为7,全局钩子监听鼠标消息设为14 

        /// </summary> 

        public const int WH_KEYBOARD = 13; 

        public const int WH_MOUSE_LL = 14; 

        public struct KeyboardMSG 

        { 

            public int vkCode; 

            public int scanCode; 

            public int flags; 

            public int time; 

            public int dwExtraInfo; 

        } 

        //private FileStream MyFs;

//各种键位的ASC码 

        private const byte LLKHF_ALTDOWN = 0x20; 

        private const byte VK_CAPITAL = 0x14; 

        private const byte VK_ESCAPE = 0x1B; 

        private const byte VK_F4 = 0x73; 

        private const byte VK_LCONTROL = 0xA2; 

        private const byte VK_NUMLOCK = 0x90; 

        private const byte VK_RCONTROL = 0xA3; 

        private const byte VK_SHIFT = 0x10; 

        private const byte VK_TAB = 0x09; 

        //public const int WH_KEYBOARD = 13; 

        private const int WH_KEYBOARD_LL = 13; 

        private const int WH_MOUSE = 7; 

        //private const int WH_MOUSE_LL = 14; 

        private const int WM_KEYDOWN = 0x100; 

        private const int WM_KEYUP = 0x101; 

        private const int WM_LBUTTONDBLCLK = 0x203; 

        private const int WM_LBUTTONDOWN = 0x201; 

        private const int WM_LBUTTONUP = 0x202; 

        private const int WM_MBUTTONDBLCLK = 0x209; 

        private const int WM_MBUTTONDOWN = 0x207; 

        private const int WM_MBUTTONUP = 0x208; 

        private const int WM_MOUSEMOVE = 0x200; 

        private const int WM_MOUSEWHEEL = 0x020A; 

        private const int WM_RBUTTONDBLCLK = 0x206; 

        private const int WM_RBUTTONDOWN = 0x204; 

        private const int WM_RBUTTONUP = 0x205; 

        private const int WM_SYSKEYDOWN = 0x104; 

        private const int WM_SYSKEYUP = 0x105; 

        //private static int hKeyboardHook = 0; 

        /// <summary> 

        /// vs2008中的声明方法，在vs2010中略有不同 

        /// </summary> 

        /// <returns></returns> 

        [DllImport("kernel32")] 

        public static extern int GetCurrentThreadId(); 

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = 

CallingConvention.StdCall)] 

        public static extern int SetWindowsHookEx(int idHook, KeyboardProc lpfn, IntPtr 

hInstance, int threadId); 

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = 

CallingConvention.StdCall)] 

        public static extern bool UnhookWindowsHookEx(int idHook); 

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] 

        public static extern int CallNextHookEx(int idHook, int nCode, IntPtr wParam, IntPtr lParam); 

        [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Winapi)] 

        public static extern short GetKeyState(int keycode); 

//在这里你可以自己定义要拦截的键。 

        private int KeyboardHookProc(int nCode, IntPtr wParam, IntPtr lParam) 

        { 

            KeyboardMSG m = (KeyboardMSG)Marshal.PtrToStructure(lParam, typeof(KeyboardMSG)); 

             if ( 

            ((int)m.vkCode == 91) || ((int)m.vkCode == 92) || 

            //两个组合键 

            ((m.vkCode == VK_TAB) && ((m.flags & LLKHF_ALTDOWN) != 0)) || 

            ((m.vkCode == VK_ESCAPE) && ((m.flags & LLKHF_ALTDOWN) != 0)) || 

            ((m.vkCode == VK_F4) && ((m.flags & LLKHF_ALTDOWN) != 0)) || 

            //用于三个组合键 

            (m.vkCode == VK_ESCAPE) && ((GetKeyState(VK_LCONTROL) & 0x8000) != 0) || 

            ((int)m.vkCode >= 65 && (int)m.vkCode <= 90 && ((GetKeyState(0x12) & 0x8000) != 0) ) || 

            ((int)m.vkCode >= 65 && (int)m.vkCode <= 90&& ((GetKeyState(0x11) & 0x8000) != 0)) || 

            (m.vkCode == VK_ESCAPE) && ((GetKeyState(VK_RCONTROL) & 0x8000) != 0) 

            ) 

            { 

                return 1; 

            } 

            return CallNextHookEx(hKeyboardHook, nCode, wParam, lParam); 

        } 

   // 安装钩子 

        public void KeyMaskStart() 

        { 

            if (hKeyboardHook == 0) 

            { 

                // 创建HookProc实例 

                KeyboardHookProcedure = new KeyboardProc(KeyboardHookProc); 

                // 设置线程钩子 

                hKeyboardHook = SetWindowsHookEx(WH_KEYBOARD, KeyboardHookProcedure, 

                    Marshal.GetHINSTANCE(Assembly.GetExecutingAssembly().GetModules()[0]), 0); 

                // 如果设置钩子失败 

                if (hKeyboardHook == 0) 

                { 

                    KeyMaskStop(); 

                    throw new Exception("SetWindowsHookEx failed."); 

                } 

                ////用二进制流的方法打开任务管理器。而且不关闭流.这样任务管理器就打开不了 

                //MyFs = new FileStream(Environment.ExpandEnvironmentVariables("%windir%\\system32\\taskmgr.exe"), 

                //FileMode.Open); 

                //byte[] MyByte = new byte[(int)MyFs.Length]; 

                //MyFs.Write(MyByte, 0, (int)MyFs.Length); 

            } 

        } 

        // 卸载钩子 

        public void KeyMaskStop() 

        { 

            bool retKeyboard = true; 

            if (hKeyboardHook != 0) 

            { 

                retKeyboard = UnhookWindowsHookEx(hKeyboardHook); 

                hKeyboardHook = 0; 

            } 

            if (!(retKeyboard)) 

            { 

                throw new Exception("UnhookWindowsHookEx  failed."); 

            } 

        } 

    } 

}

第三步：这个时候你会发现，程序能屏蔽大部分的热键了，唯独ctrl+alt+del，你无论怎么去拦截，只要你按下这三个键，任务管理器活灵活现的出来了。

原因：这个组合键是系统级别滴（唯一的，ctrl+shift+esc不是）。普通的软件拦截是木有用的。得驱动级啥的才行吧。

既然如此，就只能转换思路了。既然不能治本，治标也行，只要能达到目的。

思路有两个：1是让任务管理器一旦运行就被结束，让用户不能操作。2是让任务管理器以另外的方式先运行并隐藏起来，用户就不能运行了。

思路1的代码：使用timer控件

//引用这个空间using System.Diagnostics; 

        private void timer1_Tick(object sender, EventArgs e) 

        { 

            Process[] p = Process.GetProcesses(); 

            foreach (Process p1 in p) 

            { 

                try

                { 

                    if (p1.ProcessName.ToLower().Trim() == "taskmgr")//这里判断是任务管理器    

                    { 

                        p1.Kill(); 

                        return; 

                    } 

                } 

                catch

                { 

                    return; 

                } 

            } 

        }

思路2有两个比较好的办法

还有个不咋滴的办法，就是以文件流的方式打开taskmgr.exe（代码在上面的KeyboardHookDLL中能找到），在xp下还行，到win7下面就会有提示了。

办法1：以隐藏的方式运行。

using System; 

using System.Collections.Generic; 

using System.ComponentModel; 

using System.Data; 

using System.Drawing; 

using System.Text; 

using System.Windows.Forms; 

using Microsoft.Win32; 

using System.Diagnostics; 

using System.Runtime.InteropServices; 

namespace KidWorld 

{ 

    public partial class Form1 : Form 

    { 

        [DllImport("user32.dll")] 

        public static extern int FindWindow(string lpClassName, string lpWindowName); 

        [DllImport("User32.dll")] 

        public static extern Int32 SendMessage( 

        int hWnd, // handle to destination window 

        int Msg, // message 

        int wParam, // first message parameter 

        int lParam); // second message parameter 

        public Form1() 

        { 

            InitializeComponent(); 

        } 

        private void Form1_Load(object sender, EventArgs e) 

        { 

            Process p = new Process(); 

            p.StartInfo.WorkingDirectory = Environment.GetFolderPath(Environment.SpecialFolder.System); 

            p.StartInfo.FileName = "taskmgr.exe"; 

            p.StartInfo.CreateNoWindow = true; 

            p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden; 

            p.Start(); 

        } 

        private void Form1_FormClosing(object sender, FormClosingEventArgs e) 

        { 

            const int WM_CLOSE = 0x0010; 

            int taskManager = FindWindow("#32770", "Windows Task Manager"); 

            SendMessage(taskManager, WM_CLOSE, 0, 0); 

        } 

    } 

}

办法2：

private void Form1_Load(object sender, EventArgs e) 

        { 

            //this.Text =Environment.GetFolderPath( Environment.SpecialFolder.System).ToString(); 

            blockTaskMgr(); 

        } 

        void blockTaskMgr() { 

            //阻塞其他程序读取 

            Stream oStream = File.Open(@"C:\WINDOWS\system32\taskmgr.exe", FileMode.OpenOrCreate, FileAccess.Write); 

        }