c#中使用钩子
相信以前用过VB、Delphi，特别是VC的程序员应该对钩子程序都不陌生。在C#中我们同样可以使用钩子程序来实现特殊效果，比如当用户按下某个特殊键时提示，比如关闭应用程序前提示等。 当然使用方法相对VC来说要稍微复杂一点，有的地方还不太方便，下面的例子中实现两个基本功能： 1、按下Alt+F4时使窗口最小化 2、关闭应用程序前提示 不过目前只能捕获消息，不能屏蔽消息，我正在实验，也希望知道的高手能多多指教 一、加入winuser.h中的定义 因为钩子程序一般情况下都是在vc下使用的，在c#里面并没有对应的方法、结构等的定义，我们首先需要把winuser.h中的相关定义加入自己的类
钩子类型的枚举
public enum HookType : int
{
WH_JOURNALRECORD = ,
WH_JOURNALPLAYBACK = ,
WH_KEYBOARD = ,
WH_GETMESSAGE = ,
WH_CALLWNDPROC = ,
WH_CBT = ,
WH_SYSMSGFILTER = ,
WH_MOUSE = ,
WH_HARDWARE = ,
WH_DEBUG = ,
WH_SHELL = ,
WH_FOREGROUNDIDLE = ,
WH_CALLWNDPROCRET = ,
WH_KEYBOARD_LL = ,
WH_MOUSE_LL =
}具体的说明在msdn中都可以查到，主要的比如WH_KEYBOARD是监控按键事件，WH_CALLWNDPROC是在消息触发时执行
虚键值的定义
public enum VirtualKeys
{
VK_SHIFT = 0x10,
VK_CONTROL = 0x11,
VK_MENU = 0x12, //ALT
VK_PAUSE = 0x13,
VK_CAPITAL = 0x14
}这个不用说明了，对应ALT、CTRL等键
消息结构体
public struct CWPSTRUCT
{
public IntPtr lparam;
public IntPtr wparam;
public int message;
public IntPtr hwnd;
}这个是windows内部传递过来的消息的结构 二、加入自己定义的委托和事件参数
钩子委托
public delegate int HookProc(int code, IntPtr wParam, IntPtr lParam);
public delegate void HookEventHandler(object sender, HookEventArgs e);HokkProc是SetWindowsHookEx调用时的委托事件，HookEventHandler是自己的委托事件
钩子事件参数
public class HookEventArgs : EventArgs
{
public int HookCode;
public IntPtr wParam;
public IntPtr lParam;
public Keys key;
public bool bAltKey;
public bool bCtrlKey;
}是自己的委托事件中接受的事件参数 三、实现自己的钩子类 这一步是最重要的，要使用钩子，我们需要引用user32.dll中的相应方法：
[DllImport("user32.dll")]
static extern IntPtr SetWindowsHookEx(HookType hook, HookProc callback, IntPtr hMod, uint dwThreadId);
[DllImport("user32.dll")]
static extern bool UnhookWindowsHookEx(IntPtr hhk);
[DllImport("user32.dll")]
static extern int CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
[DllImport("user32.dll")]
static extern short GetKeyState(VirtualKeys nVirtKey);SetWindowsHookEx是注册一个钩子程序，UnhookWindowsHookEx是释放钩子程序，CallNextHookEx调用钩子的后续事件处理，GetKeyState得到所按的虚键 然后就可以调用这些方法来实现钩子程序，比如注册一个钩子可以调用：
m_hook = SetWindowsHookEx(m_hooktype, m_hookproc, IntPtr.Zero, (uint)AppDomain.GetCurrentThreadId());其中m_hooktype就是HookType中定义的类型，m_hookproc就是实际的钩子处理程序：
m_hookproc = new HookProc(KeyHookProcedure);最关键的就是KeyHookProcedure等钩子处理程序：
protected int KeyHookProcedure(int code, IntPtr wParam, IntPtr lParam)
{
if (code != )
{
return CallNextHookEx(m_hook, code, wParam, lParam);
}
if (HookInvoked != null)
{
Keys key = (Keys)wParam.ToInt32();
HookEventArgs eventArgs = new HookEventArgs();
eventArgs.key = key;
eventArgs.lParam = lParam;
eventArgs.wParam = wParam;
eventArgs.HookCode = code;
eventArgs.bAltKey = GetKeyState(VirtualKeys.VK_MENU) <= -;
eventArgs.bCtrlKey = GetKeyState(VirtualKeys.VK_CONTROL) <= -;
HookInvoked(this, eventArgs);
}
return CallNextHookEx(m_hook, code, wParam, lParam);
}在这个事件中可以取得消息的参数，特别是按键的值，然后通过HookInvoked委托调用事件实际的处理程序 四、在应用程序中调用钩子类 我们可以在自己的form中声明两个钩子对象
private MyHook callProcHook = new MyHook(HookType.WH_CALLWNDPROC);
private MyHook keyHook = new MyHook(HookType.WH_KEYBOARD);然后在初始化时注册钩子：
private void Form1_Load(object sender, EventArgs e)
{
keyHook.HookInvoked += new HookEventHandler(keyHook_HookInvoked);
keyHook.Install();
callProcHook.HookInvoked += new HookEventHandler(callProcHook_HookInvoked);
callProcHook.Install();
}然后就是实际的钩子事件：
private void keyHook_HookInvoked(object sender, HookEventArgs e)
{
if (e.key == Keys.F4 && e.bAltKey) //Alt + F4
{
this.WindowState = FormWindowState.Minimized;
}
}
private void callProcHook_HookInvoked(object sender, HookEventArgs e)
{
unsafe
{
CWPSTRUCT* message = (CWPSTRUCT*)e.lParam;
if (message != null)
{
if (message->message == WM_CLOSE)
{
(sender as MyHook).CallNextProc = false;
MessageBox.Show("程序即将关闭！");
}
}
}
}这样我们就可以通过钩子实现一些相对底层的应用。 代码说的有点乱，我就把最主要的代码直接列在下面供大家参考：
例子代码
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace HookTest
{
public partial class Form1 : Form
{
#region 消息定义(WinUser.h中定义)
private const int WM_PAINT = 0x000F;
private const int WM_CLOSE = 0x0010;
private const int WM_QUIT = 0x0012;
private const int WM_DESTROY = 0x0002;
#endregion
private MyHook callProcHook = new MyHook(HookType.WH_CALLWNDPROC);
private MyHook keyHook = new MyHook(HookType.WH_KEYBOARD);
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
keyHook.HookInvoked += new HookEventHandler(keyHook_HookInvoked);
keyHook.Install();
callProcHook.HookInvoked += new HookEventHandler(callProcHook_HookInvoked);
callProcHook.Install();
}
private void keyHook_HookInvoked(object sender, HookEventArgs e)
{
if (e.key == Keys.F4 && e.bAltKey) //Alt + F4
{
this.WindowState = FormWindowState.Minimized;
}
}
private void callProcHook_HookInvoked(object sender, HookEventArgs e)
{
unsafe
{
CWPSTRUCT* message = (CWPSTRUCT*)e.lParam;
if (message != null)
{
if (message->message == WM_CLOSE)
{
(sender as MyHook).CallNextProc = false;
MessageBox.Show("程序即将关闭！");
}
}
}
}
}
#region 消息结构体(参照WinUser.h中定义)
public struct CWPSTRUCT
{
public IntPtr lparam;
public IntPtr wparam;
public int message;
public IntPtr hwnd;
}
#endregion
#region 钩子类型的枚举
public enum HookType : int
{
WH_JOURNALRECORD = ,
WH_JOURNALPLAYBACK = ,
WH_KEYBOARD = ,
WH_GETMESSAGE = ,
WH_CALLWNDPROC = ,
WH_CBT = ,
WH_SYSMSGFILTER = ,
WH_MOUSE = ,
WH_HARDWARE = ,
WH_DEBUG = ,
WH_SHELL = ,
WH_FOREGROUNDIDLE = ,
WH_CALLWNDPROCRET = ,
WH_KEYBOARD_LL = ,
WH_MOUSE_LL =
}
#endregion
#region 虚键值的定义(参照WinUser.h中定义)
public enum VirtualKeys
{
VK_SHIFT = 0x10,
VK_CONTROL = 0x11,
VK_MENU = 0x12, //ALT
VK_PAUSE = 0x13,
VK_CAPITAL = 0x14
}
#endregion
#region 钩子委托
public delegate int HookProc(int code, IntPtr wParam, IntPtr lParam);
public delegate void HookEventHandler(object sender, HookEventArgs e);
#endregion
#region 钩子事件参数
public class HookEventArgs : EventArgs
{
public int HookCode;
public IntPtr wParam;
public IntPtr lParam;
public Keys key;
public bool bAltKey;
public bool bCtrlKey;
}
#endregion
#region 钩子类
public class MyHook
{
#region 调用Windows API
[DllImport("user32.dll")]
static extern IntPtr SetWindowsHookEx(HookType hook, HookProc callback, IntPtr hMod, uint dwThreadId);
[DllImport("user32.dll")]
static extern bool UnhookWindowsHookEx(IntPtr hhk);
[DllImport("user32.dll")]
static extern int CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam);
[DllImport("user32.dll")]
static extern short GetKeyState(VirtualKeys nVirtKey);
#endregion
#region 局部变量
private IntPtr m_hook;
private HookType m_hooktype;
private HookProc m_hookproc;
private bool _bCallNext;
public bool CallNextProc
{
get { return _bCallNext; }
set { _bCallNext = value; }
}
#endregion
public event HookEventHandler HookInvoked;
public void Install()
{
m_hook = SetWindowsHookEx(m_hooktype, m_hookproc, IntPtr.Zero, (uint)AppDomain.GetCurrentThreadId());
}
public void Uninstall()
{
if (m_hook != IntPtr.Zero)
{
UnhookWindowsHookEx(m_hook);
}
}
public MyHook(HookType HookType)
{
m_hooktype = HookType;
if (m_hooktype == HookType.WH_KEYBOARD)
{
m_hookproc = new HookProc(KeyHookProcedure);
}
else if (m_hooktype == HookType.WH_CALLWNDPROC)
{
m_hookproc = new HookProc(CallProcHookProcedure);
}
}
protected int KeyHookProcedure(int code, IntPtr wParam, IntPtr lParam)
{
if (code != )
{
return CallNextHookEx(m_hook, code, wParam, lParam);
}
if (HookInvoked != null)
{
Keys key = (Keys)wParam.ToInt32();
HookEventArgs eventArgs = new HookEventArgs();
eventArgs.key = key;
eventArgs.lParam = lParam;
eventArgs.wParam = wParam;
eventArgs.HookCode = code;
eventArgs.bAltKey = GetKeyState(VirtualKeys.VK_MENU) <= -;
eventArgs.bCtrlKey = GetKeyState(VirtualKeys.VK_CONTROL) <= -;
HookInvoked(this, eventArgs);
}
return CallNextHookEx(m_hook, code, wParam, lParam);
}
protected int CallProcHookProcedure(int code, IntPtr wParam, IntPtr lParam)
{
try
{
CallNextProc = true;
if (HookInvoked != null)
{
HookEventArgs eventArgs = new HookEventArgs();
eventArgs.lParam = lParam;
eventArgs.wParam = wParam;
eventArgs.HookCode = code;
HookInvoked(this, eventArgs);
}
if (CallNextProc)
{
return CallNextHookEx(m_hook, code, wParam, lParam);
}
else
{
//return 1;
return CallNextHookEx(IntPtr.Zero, code, wParam, lParam);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
return ;
}
}
}
#endregion
}以上的钩子只对当前应用程序起作用，如果想控制其他的所有程序，需要使用全局钩子。原则上全局钩子在C#中是不支持的，在http://www.codeproject.com/csharp/globalhook.asp 中的代码可以参照来实现全局钩子
本文参与 腾讯云自媒体同步曝光计划，分享自作者个人站点/博客。
原始发表：2008-05-22 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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