c++ - 如何向键盘添加钩子(Hook) (HookProc)

Question

我试图做一个简单的键盘记录测试，但我的程序没有按预期工作，我也不知道为什么。

在我的程序中，我有一个低级键盘钩子(Hook)并为其附加了一个简单的过程。该过程只是打开/创建一个文件并写入“Hello World”然后关闭。但是它没有创建文件，可能是因为我的过程不正确或者因为我的 Hook 没有正确建立。

代码:

#include<windows.h>
#include<stdio.h>
#include <iostream>
#include <fstream>

using namespace std;

LRESULT CALLBACK KeyboardProc(int code, WPARAM wParam, LPARAM lParam){
    ofstream myfile;
        myfile.open ("[PATH]/example.txt");
        myfile << "Hello world";//((KBDLLHOOKSTRUCT *)lParam)->vkCode
    myfile.close();
    return CallNextHookEx(NULL,code,wParam,lParam);
}

int main(void){
    HINSTANCE hInst = NULL;
    HHOOK hHook = SetWindowsHookEx(WH_KEYBOARD_LL, KeyboardProc, hInst, 0);
    printf("HHOOK is not null: %s\n", (hHook != NULL) ? "True" : "False");
    char q;
    for (cout << "q to quit\n"; q != 'q'; cin >> q);

    printf("Successfully unhooked: %s", UnhookWindowsHookEx(hHook) ? "True" : "False");
}

解决方案 我需要在主函数中添加一个消息循环:

LPMSG Msg;
while(GetMessage(Msg, NULL, 0, 0) > 0)
{
    TranslateMessage(Msg);
    DispatchMessage(Msg);
}

Answer 1

有两种钩子(Hook):

全局钩子(Hook)
全局钩子(Hook)程序应放在一个单独的 DLL 中，然后在您的主进程中加载​​钩子(Hook) dll 及其钩子(Hook)程序并设置钩子(Hook)。

A global hook monitors messages for all threads in the same desktop as the calling thread. A thread-specific hook monitors messages for only an individual thread. A global hook procedure can be called in the context of any application in the same desktop as the calling thread, so the procedure must be in a separate DLL module.

就是说:KeyboardProc 进入一个单独的 DLL(例如 myhookdll.dll)。
在你的过程中你做这样的事情:

HOOKPROC hkprc;
static HINSTANCE hhookDLL ; 
static HHOOK hhook ; 

hhookDLL = LoadLibrary(TEXT("c:\\...\\myhookdll.dll")); 
hkprc = (HOOKPROC)GetProcAddress(hhookDLL, "KeyboardProc"); 

hhook = SetWindowsHookEx( 
                    WH_KEYBOARD,
                    hkprc,
                    hhookDLL,
                    0); 

这是一个很好的引用:http://msdn.microsoft.com/en-us/library/windows/desktop/ms644960(v=vs.85).aspx

线程级 Hook
关于这个在线程级 Hook 的特定“WH_KEYBOARD_LL”，它不需要单独的 DLL。

A thread-specific hook procedure is called only in the context of the associated thread. If an application installs a hook procedure for one of its own threads, the hook procedure can be in either the same module as the rest of the application's code or in a DLL. If the application installs a hook procedure for a thread of a different application, the procedure must be in a DLL. For information, see Dynamic-Link Libraries.

但是线程级钩子(Hook)需要一个消息泵:

This hook is called in the context of the thread that installed it. The call is made by sending a message to the thread that installed the hook. Therefore, the thread that installed the hook must have a message loop.

这是一个基本的消息循环:

   while((bRet = GetMessage(&msg, NULL, 0, 0)) != 0)
   {
     if(bRet == -1)
     {
         // Handle Error
     }
     else
     {
         TranslateMessage(&msg);
         DispatchMessage(&msg);
     }
   }