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);          }

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C# 键盘钩子