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麼逃，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，在目的視窗處理鍵代碼前攔截把某個指令替換為另外一種指令，然後再把訊息傳送給目的視窗這樣一個周期下來，視窗程序會認為使用者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裡則成為了 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);    // 安裝全域鍵盤鉤子    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; // 返回1表示攔截訊息，返回0表示允許存取    return CallNextHookEx(hHook, code, wParam, lParam);}

監控系統內所有進程鍵盤訊息：
SetWindowsHookEx(WH_KEYBOARD_LL, KeyBoardProc, NULL, NULL)

        // 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);
            // 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; // 返回1表示攔截訊息，返回0表示允許存取    return CallNextHookEx(hHook, code, wParam, lParam);}
監控本進程的所有鍵盤訊息：
     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);   }
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