用户按下该键时无法看到该消息

Question

以下java程序调用{​​{1}}中的本机方法，如果用户按下某个键，则该方法应打印消息C。但我无法看到消息，因为我按下了键。我还检查函数you pressed a key !是否返回null但不是，它不返回null。

Java代码：

SetWindowsHookEx

} C代码：

package keylogger;

public class TestKeys {

private native void setWinHook();

public static void main(String args[]) {
    TestKeys o = new TestKeys();
    try {
        o.setWinHook();
        Thread.sleep(10000);
    } catch(Exception exc) {
        exc.printStackTrace();
    }
}

static {
    System.loadLibrary("MyHook");
}

我看到的唯一输出是不是NullInside fucntion setWinHook！

问题出在哪里？

当我按下该键时，我应该怎么做才能让该程序返回信息。 我看到的唯一输出是：#include <stdio.h> #include <windows.h> #include <w32api.h> #include "keylogger_TestKeys.h" static HHOOK handleKeyboardHook = NULL; HINSTANCE hInst = NULL; static LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam) { printf("You pressed a key !\n"); return CallNextHookEx(handleKeyboardHook, nCode, wParam, lParam); } void Java_keylogger_TestKeys_setWinHook (JNIEnv *env, jobject obj) { hInst = GetModuleHandle(NULL); // include or exclude,i don't see the result handleKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc,NULL, 0); if(handleKeyboardHook==NULL) { printf("Is Null"); } else { printf("Is not Null"); } printf("Inside fucntion setWinHook !"); } /*int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { printf("Hello World !"); handleKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hInstance, 0); if(handleKeyboardHook==NULL) { printf("Is Null"); } else { printf("Is not Null"); } MSG msg; while(GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg); DispatchMessage(&msg); } return msg.wParam; }*/

注意：

如果上述程序在某人的机器上运行，请提及。

输出图片：

我没有在按键上看到任何消息。程序只在10秒后退出而不显示消息。

Answer 1

您不能简单地声明本地HINSTANCE变量并将其传递给函数。 HINSTANCE是应用程序实例的句柄，换句话说，指针必须指向有效位置。您需要使用属于您自己的应用程序的HINSTANCE。

我的Windows API有点生疏，但我相信你可以通过GetModuleHandle（）来做到这一点。 所以：

void Java_keylogger_TestKeys_setWinHook
     (JNIEnv *env, jobject obj) {
   HINSTANCE hInst;
   hInst = GetModuleHandle(null);
   handleKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hInst, 0);
   printf("Inside function setWinHook !");
 }

你的Java goo很可能在某个对象中隐藏了一个HINSTANCE。

Answer 2

查看Java Global(low level) Keyboard/Mouse Hook

我自己写了一个，但似乎有太多未知的细节（JNI，HOOKS，穿线问题等）

Answer 3

肯定有更好的方法来实现这一点。一旦创建了一个线程，就会多次调用DllMain，这对我来说似乎不对。我不确定这是否合法！ C代码启动一个新线程来实现keycatcher。

C代码：

#include <stdio.h>
#include <windows.h>
#include <w32api.h>
#include "keylogger_TestKeys.h"

static HHOOK handleKeyboardHook = NULL;
HINSTANCE hInst = NULL;
static DWORD hookThreadId = 0;
static HANDLE hookThreadHandle = NULL;
BOOL WINAPI installHook(HINSTANCE hinstDLL, DWORD fwdReason, LPVOID lpvReserved);
static int i = 0;

static LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam) {

  printf("You pressed the key !");
  return CallNextHookEx(handleKeyboardHook, nCode, wParam, lParam);
}


BOOL WINAPI DllMain( HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved) {
 if(hookThreadHandle==NULL) {
    printf("hookThreadHandle is NULL\n");
    LPTHREAD_START_ROUTINE lpStartAddress = &installHook;
    hookThreadHandle = CreateThread(NULL, 0, lpStartAddress, NULL, 0, &hookThreadId);
 }
}

BOOL WINAPI installHook(HINSTANCE hinstDLL, DWORD fwdReason, LPVOID lpvReserved) {
// printf("From installHook : %u",fwdReason);
printf("count : %d\n",i++);
handleKeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, hinstDLL, 0);
MSG msg;

while(GetMessage(&msg, NULL, 0, 0))
{
  TranslateMessage(&msg);
  DispatchMessage(&msg);
}
return msg.wParam;
}

void Java_keylogger_TestKeys_unregisterWinHook
 (JNIEnv *env, jobject obj) {
 // should have stopped the thread before unhooking
 if(handleKeyboardHook != NULL) {
    UnhookWindowsHookEx(handleKeyboardHook);
 }
}

void Java_keylogger_TestKeys_stopNativeThread // stop the native thread
  (JNIEnv *env, jobject obj) {
    PostThreadMessage(hookThreadId, WM_QUIT, (WPARAM) NULL, (LPARAM) NULL);
    WaitForSingleObject(hookThreadHandle, 5000);
}

Java代码：

package keylogger;

public class TestKeys {
private static int i = 0;
private native void setWinHook();
private native void unregisterWinHook();
private native void createWinThread();
private native void stopNativeThread();

public static void main(String args[]) {
    TestKeys o = new TestKeys();
    try {
        Thread.sleep(5000);
    }catch(Exception exc) {
        exc.printStackTrace();
    }
   o.stopNativeThread();
   o.unregisterWinHook();
   System.out.println("Native thread stopped and Hook unregistered !");

   try {
        Thread.sleep(3000); // Now you won't see the message : you pressed the key 
    }catch(Exception exc) {
        exc.printStackTrace();
    }
}

static {
    System.loadLibrary("MyHook");
}
}

我启动java程序并调用DLLMain。

Answer 4

HHOOK 变量需要在共享数据段内声明。 在这里查看它是如何完成的 - http://www.codeproject.com/Articles/5002/Mousey-Roll-Over-and-Park

Answer 5

您需要GetMessage/PeekMessage循环才能使键盘挂钩接收任何事件。有关Windows上键盘钩子的Java实现，请参阅JNA Keyboard Hook in Windows或在JNA项目中执行相同功能的贡献包（https://github.com/twall/jna/tree/master/contrib/w32keyhook）。