C# 鍵盤鉤子

鍵盤鉤子是一種可以監控鍵盤操作的指令，我們去釣魚只要魚兒上鉤

不管它怎么逃，只要掌控好鉤子上的繩子總是可以找到這條魚，鍵盤

鉤子是利用電腦一行行執行代碼特性，在目的窗口處理鍵代碼前攔截

把某個指令替換為另外一種指令，然后再把消息傳送給目的窗口這樣

一個周期下來，窗口程序會認為用戶輸入的就是現在的數值或者沒有

輸入，不過鍵盤鉤子在某些不法分子手里則成為了 盜號、監控密碼 等

違法操作。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);
            // 安裝全局鍵盤鉤子
            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, 宋體, sans-serif;font-size:18px; line-height: 24px; text-indent: 28px;">返回1表示攔截消息，返回0表示放行</span>
            return CallNextHookEx(hHook, code, wParam, lParam);
        }

監控系統內所有進程鍵盤消息：
        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;">            // 安裝鍵盤鉤子

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, 宋體, sans-serif;">// </span><span style="font-family: arial, 宋體, sans-serif;">返回1表示攔截消息，返回0表示放行</span>
            return CallNextHookEx(hHook, code, wParam, lParam);
        }

監控本進程的所有鍵盤消息：

     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);
        }