问题描述

以下java程序在C中调用本机方法，如果用户按键，该方法应打印消息you pressed a key !.但是当我按键时，我看不到消息.我还检查函数SetWindowsHookEx是否返回null，但不，它不会返回null.

java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");
}

}
C代码:

#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;
}*/

我看到的唯一输出是不是nullinside fucntion setWinhook！

问题在哪里?

我应该做什么，以便当我按键时，该程序会返回我的消息.
我看到的唯一输出是:Inside function setWinHook !

注意:

如果以上程序在某人的机器上运行，请提及.

输出图片:

我在键敲击上看不到任何消息.

推荐答案

肯定有一种更好的方法来实现此目标.在这里DllMain创建线程后，多次被称为多次，这对我来说似乎并不正确.我不确定这是否合法！ C代码启动了一个新线程以实现键盘.

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");
}
}

i启动Java程序，DLLMain被称为.

其他推荐答案

您不能简单地从蓝色中声明本地hinstance变量，然后将其传递给函数. hinstance是您应用程序实例的处理方法，换句话说，必须指向有效位置的指针.您需要使用自己的应用程序.

我的Windows API有点生锈，但我相信您可以通过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 !");
 }

您的Java Goo很可能在某个地方隐藏了一个hinstance.

其他推荐答案

查看 java global(低级)键盘/鼠标钩

我试图自己写一个，但是对我来说似乎有太多未知细节(JNI，钩子，线程问题等)

)

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