hook（钩子）是windows提供的一种消息处理机制平台，是指在程序正常运行中接受信息之前预先启动的函数，用来检查和修改传给该程序的信息，（钩子）实际上是一个处理消息的程序段，通过系统调用，把它挂入系统。每当特定的消息发出， 在没有到达目的窗口前，钩子程序就先捕获该消息，亦即钩子函数先得到控制权。这时钩子函数即可以加工处理（改变）该消息，也可以不作处理而继续传递该消息，还可以强制结束消息的传递(return)。
运行下面的程序案例需注意，程序会全屏展示，并且拦截所有系统组合键（除ctrl+alt+del），在程序菜单栏可退出。
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using static WindowsFormsApplication1.Win32Api;
namespace WindowsFormsApplication1
{
/**
* c#钩子程序 键盘监控(拦截系统组合键)
* */
public class Win32Api
{
#region 常数和结构
public const int WM_KEYDOWN = 0x100;
public const int WM_KEYUP = 0x101;
public const int WM_SYSKEYDOWN = 0x104;
public const int WM_SYSKEYUP = 0x105;
public const int WH_KEYBOARD_LL = 13;
[StructLayout(LayoutKind.Sequential)] //声明键盘钩子的封送结构类型
public class KeyboardHookStruct
{
public int vkCode; //表示一个在1到254间的虚似键盘码
public int scanCode; //表示硬件扫描码
public int flags;
public int time;
public int dwExtraInfo;
}
#endregion
#region Api
public delegate int HookProc(int nCode, Int32 wParam, IntPtr lParam);
//安装钩子的函数
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);
//卸下钩子的函数
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern bool UnhookWindowsHookEx(int idHook);
//下一个钩挂的函数
[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern int CallNextHookEx(int idHook, int nCode, Int32 wParam, IntPtr lParam);
[DllImport("user32")]
public static extern int ToAscii(int uVirtKey, int uScanCode, byte[] lpbKeyState, byte[] lpwTransKey, int fuState);
[DllImport("user32")]
public static extern int GetKeyboardState(byte[] pbKeyState);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern IntPtr GetModuleHandle(string lpModuleName);
#endregion
}
public class KeyboardHook
{
int hHook;
Win32Api.HookProc KeyboardHookDelegate;
public event KeyEventHandler OnKeyDownEvent;
public event KeyEventHandler OnKeyUpEvent;
public event KeyPressEventHandler OnKeyPressEvent;
public KeyboardHook() { }
/**
* 设置钩子
* */
public void SetHook()
{
KeyboardHookDelegate = new Win32Api.HookProc(KeyboardHookProc);
Process cProcess = Process.GetCurrentProcess();
ProcessModule cModule = cProcess.MainModule;
var mh = Win32Api.GetModuleHandle(cModule.ModuleName);
hHook = Win32Api.SetWindowsHookEx(Win32Api.WH_KEYBOARD_LL, KeyboardHookDelegate, mh, 0);
}
/**
* 卸载钩子
* */
public void UnHook()
{
Win32Api.UnhookWindowsHookEx(hHook);
}
/**
* 拦截按键
* nCode参数是钩子代码，钩子子程使用这个参数来确定任务，这个参数的值依赖于Hook类型。
* wParam和lParam参数包含了消息信息，我们可以从中提取需要的信息。
* */
private int KeyboardHookProc(int nCode, Int32 wParam, IntPtr lParam)
{
if (nCode >= 0)
{
KeyboardHookStruct kbh = (KeyboardHookStruct)Marshal.PtrToStructure(lParam, typeof(KeyboardHookStruct));
// 截获左win(开始菜单键)
if (kbh.vkCode == 91)
{
return 1;
}
// 截获右win
if (kbh.vkCode == 92)
{
return 1;
}
//截获Ctrl+Esc
if (kbh.vkCode == (int)Keys.Escape && (int)Control.ModifierKeys == (int)Keys.Control)
{
return 1;
}
//截获alt+f4
if (kbh.vkCode == (int)Keys.F4 && (int)Control.ModifierKeys == (int)Keys.Alt)
{
return 1;
}
//截获alt+tab
if (kbh.vkCode == (int)Keys.Tab && (int)Control.ModifierKeys == (int)Keys.Alt)
{
return 1;
}
//截获Ctrl+Shift+Esc
if (kbh.vkCode == (int)Keys.Escape && (int)Control.ModifierKeys == (int)Keys.Control + (int)Keys.Shift)
{
return 1;
}
//截获alt+空格
if (kbh.vkCode == (int)Keys.Space && (int)Control.ModifierKeys == (int)Keys.Alt)
{
return 1;
}
//截获F1
if (kbh.vkCode == 241)
{
return 1;
}
//截获Ctrl+Alt+Delete
if ((int)Control.ModifierKeys == (int)Keys.Control + (int)Keys.Alt + (int)Keys.Delete)
{
return 1;
}
}
return Win32Api.CallNextHookEx(hHook, nCode, wParam, lParam);
}
}
}using System;
using System.Windows.Forms;
/**
* 命名空间，类似于java中的import
* */
namespace WindowsFormsApplication1
{
static class Program
{
/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
}using System;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
partial class Form1
{
/// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// 清理所有正在使用的资源。
/// </summary>
/// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows 窗体设计器生成的代码
/// <summary>
/// 设计器支持所需的方法 - 不要修改
/// 使用代码编辑器修改此方法的内容。
/// </summary>
private void InitializeComponent()
{
this.menuStrip1 = new System.Windows.Forms.MenuStrip();
this.菜单ToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
this.退出程序ToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
this.考试须知ToolStripMenuItem = new System.Windows.Forms.ToolStripMenuItem();
this.webBrowser1 = new System.Windows.Forms.WebBrowser();
this.menuStrip1.SuspendLayout();
this.SuspendLayout();
//
// menuStrip1
//
this.menuStrip1.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {
this.菜单ToolStripMenuItem,
this.考试须知ToolStripMenuItem});
this.menuStrip1.Location = new System.Drawing.Point(0, 0);
this.menuStrip1.Name = "menuStrip1";
this.menuStrip1.Size = new System.Drawing.Size(893, 25);
this.menuStrip1.TabIndex = 0;
this.menuStrip1.Text = "menuStrip1";
//
// 菜单ToolStripMenuItem
//
this.菜单ToolStripMenuItem.DropDownItems.AddRange(new System.Windows.Forms.ToolStripItem[] {
this.退出程序ToolStripMenuItem});
this.菜单ToolStripMenuItem.Name = "菜单ToolStripMenuItem";
this.菜单ToolStripMenuItem.Size = new System.Drawing.Size(44, 21);
this.菜单ToolStripMenuItem.Text = "菜单";
//
// 退出程序ToolStripMenuItem
//
this.退出程序ToolStripMenuItem.Name = "退出程序ToolStripMenuItem";
this.退出程序ToolStripMenuItem.Size = new System.Drawing.Size(124, 22);
this.退出程序ToolStripMenuItem.Text = "退出程序";
this.退出程序ToolStripMenuItem.Click += new System.EventHandler(this.退出程序ToolStripMenuItem_Click);
//
// 考试须知ToolStripMenuItem
//
this.考试须知ToolStripMenuItem.Name = "考试须知ToolStripMenuItem";
this.考试须知ToolStripMenuItem.Size = new System.Drawing.Size(68, 21);
this.考试须知ToolStripMenuItem.Text = "考试须知";
this.考试须知ToolStripMenuItem.Click += new System.EventHandler(this.考试须知ToolStripMenuItem_Click);
//
// webBrowser1 属性设置
//
this.webBrowser1.Dock = System.Windows.Forms.DockStyle.Fill;
this.webBrowser1.Location = new System.Drawing.Point(0, 25);
this.webBrowser1.MinimumSize = new System.Drawing.Size(20, 20);
this.webBrowser1.Name = "webBrowser1";
this.webBrowser1.Size = new System.Drawing.Size(893, 286);
this.webBrowser1.TabIndex = 1;
/**
* 设置 WebBrowser 容器默认请求的ip地址
* */
this.webBrowser1.Navigate("http://www.baidu.com");
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size(893, 311);
this.Controls.Add(this.webBrowser1);
this.Controls.Add(this.menuStrip1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
this.MainMenuStrip = this.menuStrip1;
this.Name = "Form1";
this.ShowInTaskbar = false;
this.Text = "Form1";
this.TopMost = true;
this.WindowState = System.Windows.Forms.FormWindowState.Maximized;//窗体最大化
this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.Form1_FormClosing);
this.Load += new System.EventHandler(this.Form1_Load);
this.menuStrip1.ResumeLayout(false);
this.menuStrip1.PerformLayout();
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
/**
* 定义菜单
* */
private MenuStrip menuStrip1;
/**
* 定义菜单按钮
* */
private ToolStripMenuItem 菜单ToolStripMenuItem;
private ToolStripMenuItem 退出程序ToolStripMenuItem;
private ToolStripMenuItem 考试须知ToolStripMenuItem;
/**
* 定义WebBrowser容器
* */
private WebBrowser webBrowser1;
}
}using System;
using System.Diagnostics;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
/**
* 窗体类
* */
public partial class Form1 : Form
{
public Form1()
{
/**
* 容器初始化
* */
InitializeComponent();
}
/**
* 定义钩子对象
* */
KeyboardHook kh;
/**
* 窗体加载时启动 winfrom 钩子
**/
private void Form1_Load(object sender, EventArgs e)
{
kh = new KeyboardHook();
kh.SetHook();
}
/**
* 键盘事件监听
* */
void kh_OnKeyDownEvent(object sender, KeyEventArgs e)
{
}
/**
* 窗体关闭
* */
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
kh.UnHook();
}
/**
* 退出程序
* */
private void 退出程序ToolStripMenuItem_Click(object sender, EventArgs e)
{
Process.GetCurrentProcess().Kill();
}
private void 考试须知ToolStripMenuItem_Click(object sender, EventArgs e)
{
MessageBox.Show("考生请注意：作弊者，格杀勿论，不留余地~");
}
}
}