C# 键盘钩子

键盘钩子是一种可以监控键盘操作的指令，我们去钓鱼只要鱼儿上钩

不管它怎么逃，只要掌控好钩子上的绳子总是可以找到这条鱼，键盘

钩子是利用电脑一行行执行代码特性，在目的窗口处理键代码前拦截

把某个指令替换为另外一种指令，然后再把消息传送给目的窗口这样

一个周期下来，窗口程序会认为用户输入的就是现在的数值或者没有

输入，不过键盘钩子在某些不法分子手里则成为了 盗号、监控密码 等

违法操作。原型：HHOOK SetWindowsHookEx(int idHook, HOOKPROC lpfn, HINSTANCE hMod, DWORD dwThreadId);

        // Win32 keyboard hook.
        public const int WH_KEYBOARD_LL = 13;
        public const int NULL = 0;

        public delegate int HookProc(int code, int wParam, KBDLLHOOKSTRUCT lParam);

        [DllImport("user32.dll", SetLastError = true)]
        public static extern int SetWindowsHookEx(int hookType, HookProc lpfn, int hMod, int dwThreadId);

        [DllImport("User32.dll", SetLastError = true)]
        public extern static int CallNextHookEx(int handle, int code, int wParam, KBDLLHOOKSTRUCT lParam);

        [StructLayout(LayoutKind.Sequential)]
        public class KBDLLHOOKSTRUCT
        {
            public uint vkCode;
            public uint scanCode;
            public KBDLLHOOKSTRUCT flags;
            public uint time;
            public UIntPtr dwExtraInfo;
        }

        [Flags]
        public enum KBDLLHOOKSTRUCT : uint
        {
            LLKHF_EXTENDED = 0x01,
            LLKHF_INJECTED = 0x10,
            LLKHF_ALTDOWN = 0x20,
            LLKHF_UP = 0x80,
        }

        public volatile int hHook;

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
            // 安装全局键盘钩子
            if ((this.hHook = SetWindowsHookEx(WH_KEYBOARD_LL, this.KeyBoardProc, NULL, NULL)) == NULL)
                Console.WriteLine("Unable to establish a keyboard hook.");
        }

        protected int KeyBoardProc(int code, int wParam, KBDLLHOOKSTRUCT lParam)
        {
            if (lParam.vkCode == (int)Keys.A)
                return 1; // <span style="font-family: arial, 宋体, sans-serif;font-size:18px; line-height: 24px; text-indent: 28px;">返回1表示拦截消息，返回0表示放行</span>
            return CallNextHookEx(hHook, code, wParam, lParam);
        }

监控系统内所有进程键盘消息：
        SetWindowsHookEx(WH_KEYBOARD_LL, KeyBoardProc, NULL, NULL)

<pre name="code" class="csharp">        // Win32 keyboard hook.
        public const int WH_KEYBOARD = 2;
        public const int NULL = 0;

        public delegate int HookProc(int code, int wParam, int lParam);

        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern int GetCurrentThreadId();

        [DllImport("user32.dll", SetLastError = true)]
        public static extern int SetWindowsHookEx(int hookType, HookProc lpfn, int hMod, int dwThreadId);

        [DllImport("User32.dll", SetLastError = true)]
        public extern static int CallNextHookEx(int handle, int code, int wParam, int lParam);

        public volatile int hHook;

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
<pre name="code" class="csharp" style="line-height: 24px;font-size:18px;">            // 安装键盘钩子

if ((this.hHook = SetWindowsHookEx(WH_KEYBOARD, KeyBoardProc, NULL, GetCurrentThreadId())) == NULL) Console.WriteLine("Unable to establish a keyboard hook."); }

        protected int KeyBoardQueue(int code, int wParam, int lParam)
        {
            if (wParam == (int)Keys.A)
                return 1; <span style="font-family: arial, 宋体, sans-serif;">// </span><span style="font-family: arial, 宋体, sans-serif;">返回1表示拦截消息，返回0表示放行</span>
            return CallNextHookEx(hHook, code, wParam, lParam);
        }

监控本进程的所有键盘消息：

     SetWindowsHookEx(WH_KEYBOARD, KeyBoardProc, NULL, GetCurrentThreadId());

     protected int KeyBoardProc(int code, int wParam, int lParam)
        {
            if (wParam == (int)Keys.A)
                return 1;
            return CallNextHookEx(hHook, code, wParam, lParam);
        }

标签： 代码

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