C#中全局鼠标、键盘Hook的应用方法

    怎样在C#中使用全局钩子？以前写的全局钩子都是用unmanaged C或C++写个DLL来实现，可大家都知道，C#是基于.Net Framework的，是managed，怎么实现全局钩子呢？于是开始到网上搜索，好不容易找到一篇，318804 - HOW TO: Set a Windows Hook in Visual C# .NET，里面详细的说明了如何使用鼠标钩子捕获鼠标的移动等，可是，它只能在Application里起作用，出了Application就没用了，就是说它还是没有实现全局钩子，而且文章结尾处说：“Global Hooks are not supported in the .NET Framework...”，这可怎么办呢？

　　别担心，办法总是有的，经过一番摸索以后，发现WH_KEYBORAD_LL和WH_MOUSE_LL这两个low-level的hook可以被安装成全局的，这就好办了，我们不妨用这两个low-level的hook替换掉WH_KEYBORAD和WH_MOUSE，于是开始测试。结果成功了，在C#里实现了全局钩子。

　　我们来看一下主要代码段。

　　首先倒入所需要的windows函数，主要有三个，SetWindowsHookEX用来安装钩子，UnhookWindowsHookEX用来卸载钩子以及CallNextHookEX用来将hook信息传递到链表中下一个hook处理过程。


[DllImport(\"user32.dll\", CharSet = CharSet.Auto,
           CallingConvention = CallingConvention.StdCall, SetLastError = true)]
        private static extern int SetWindowsHookEx(
            int idHook,
            HookProc lpfn,
            IntPtr hMod,
            int dwThreadId);

[DllImport(\"user32.dll\", CharSet = CharSet.Auto,
            CallingConvention = CallingConvention.StdCall, SetLastError = true)]
        private static extern int UnhookWindowsHookEx(int idHook);

[DllImport(\"user32.dll\", CharSet = CharSet.Auto,
             CallingConvention = CallingConvention.StdCall)]
        private static extern int CallNextHookEx(
            int idHook,
            int nCode,
            int wParam,
            IntPtr lParam);

　　下面是有关这两个low-level hook在Winuser.h中的定义：


/**//// <summary>
        /// Windows NT/2000/XP: Installs a hook procedure that monitors low-level mouse input events.
        /// </summary> [Page]
        private const int WH_MOUSE_LL       = 14;
        /**//// <summary>
        /// Windows NT/2000/XP: Installs a hook procedure that monitors low-level keyboard  input events.
        /// </summary>
        private const int WH_KEYBOARD_LL    = 13;

　　在安装全局钩子的时候，我们就要做替换了，将WH_MOUSE和WH_KEYBORAD分别换成WH_MOUSE_LL和WH_KEYBORAD_LL：


//install hook
                hMouseHook = SetWindowsHookEx(
                    WH_MOUSE_LL,　//原来是WH_MOUSE
                    MouseHookProcedure,
                    Marshal.GetHINSTANCE(
                        Assembly.GetExecutingAssembly().GetModules()[0]),
                    0);

//install hook
                hKeyboardHook = SetWindowsHookEx(

 WH_KEYBOARD_LL, //原来是WH_KEYBORAD
                    KeyboardHookProcedure,
                    Marshal.GetHINSTANCE(
                    Assembly.GetExecutingAssembly().GetModules()[0]),
                    0); [Page]
 
　　这样替换了之后，我们就可以实现全局钩子了，而且，不需要写DLL。看一下程序运行情况：

　　下面是关于鼠标和键盘的两个Callback函数：


private int MouseHookProc(int nCode, int wParam, IntPtr lParam)
        {
            // if ok and someone listens to our events
            if ((nCode >= 0) && (OnMouseActivity != null))
            {
                //Marshall the data from callback.
                MouseLLHookStruct mouseHookStruct = (MouseLLHookStruct)Marshal.PtrToStructure(lParam, typeof(MouseLLHookStruct));

                //detect button clicked
                MouseButtons button = MouseButtons.None;
                short mouseDelta = 0;
                switch (wParam)
                {
                    case WM_LBUTTONDOWN:
                        //case WM_LBUTTONUP: 
                        //case WM_LBUTTONDBLCLK: 
                        button = MouseButtons.Left;
                        break; [Page]
                    case WM_RBUTTONDOWN:
                        //case WM_RBUTTONUP: 
                        //case WM_RBUTTONDBLCLK: 
                        button = MouseButtons.Right;
                        break;
                    case WM_MOUSEWHEEL:
                        //If the message is WM_MOUSEWHEEL, the high-order word of mouseData member is the wheel delta. 
                        //One wheel click is defined as WHEEL_DELTA, which is 120. 
                        //(value >> 16) & 0xffff; retrieves the high-order word from the given 32-bit value

mouseDelta = (short)((mouseHookStruct.mouseData >> 16) & 0xffff);
                        //TODO: X BUTTONS (I havent them so was unable to test)
                        //If the message is WM_XBUTTONDOWN, WM_XBUTTONUP, WM_XBUTTONDBLCLK, WM_NCXBUTTONDOWN, WM_NCXBUTTONUP,  [Page]
                        //or WM_NCXBUTTONDBLCLK, the high-order word specifies which X button was pressed or released,
                        //and the low-order word is reserved. This value can be one or more of the following values.
                        //Otherwise, mouseData is not used.
                        break;
                }

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【责编:Ken】