Turn off/ignore win, alt, and ctrl keys

**Melawe** · August 30th, 2012, 01:02 PM

Hello,

I'm coding an application for the daughter of a friend, and need to swtich off the win(super), alt, and ctrl keys. I got some native code from the net, but it seams its not working on Win 7. The program works well, no error messages or anything of that sort, the only problem is, the alt, ctrl, and win(super) key are still working.

The code below would be called in the key event handlers, but doesn't do the job as required. It was only tested on win 7 by the client. Since I don't have windows of any version atm, I can't test it to know how it works on other versions.

 
import com.sun.jna.platform.win32.Kernel32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HMODULE;
import com.sun.jna.platform.win32.WinDef.LRESULT;
import com.sun.jna.platform.win32.WinDef.WPARAM;
import com.sun.jna.platform.win32.WinUser.HHOOK;
import com.sun.jna.platform.win32.WinUser.KBDLLHOOKSTRUCT;
import com.sun.jna.platform.win32.WinUser.LowLevelKeyboardProc;
import com.sun.jna.platform.win32.WinUser.MSG;
 
class KeyHook {
 
    private static HHOOK hhk;
    private static LowLevelKeyboardProc keyboardHook;
    private static User32 lib;
 
    public static void blockWindowsKey() {
        if (isWindows()) {
            new Thread(new Runnable() {
 
                @Override
                public void run() {
                    lib = User32.INSTANCE;
                    HMODULE hMod = Kernel32.INSTANCE.GetModuleHandle(null);
                    keyboardHook = new LowLevelKeyboardProc() {
                        public LRESULT callback(int nCode, WPARAM wParam, KBDLLHOOKSTRUCT info) {
                            if (nCode >= 0) {
                                switch (info.vkCode){
                                    case 0x5B:
                                    case 0x5C:
                                    return new LRESULT(1);
                                    default: //do nothing
                                }
                            }
                            return lib.CallNextHookEx(hhk, nCode, wParam, info.getPointer());
                        }
                    };
                    hhk = lib.SetWindowsHookEx(13, keyboardHook, hMod, 0);
 
                    // This bit never returns from GetMessage
                    int result;
                    MSG msg = new MSG();
                    while ((result = lib.GetMessage(msg, null, 0, 0)) != 0) {
                        if (result == -1) {
                            break;
                        } else {
                            lib.TranslateMessage(msg);
                            lib.DispatchMessage(msg);
                        }
                    }
                    lib.UnhookWindowsHookEx(hhk);
                }
            }).start();
        }
    }
 
    public static void unblockWindowsKey() {
        if (isWindows() && lib != null) {
            lib.UnhookWindowsHookEx(hhk);
        }
    }
 
    public static boolean isWindows(){
        String os = System.getProperty("os.name").toLowerCase();
            return (os.indexOf( "win" ) >= 0);
    }
}

I tried changing the last part of the code

public static boolean isWindows(){
        String os = System.getProperty("os.name").toLowerCase();
            return (os.indexOf( "win" ) >= 0);
    }

to

public static boolean isWindows(){
        String os = System.getProperty("os.name").toLowerCase();
            return (os.indexOf( "windows 7" ) >= 0);
    }

But that didn't work as well.

**curmudgeon** · August 30th, 2012, 01:09 PM

This looks to be code that uses the JNA library. Do you mean to be saying that you've tested this code on other versions of Window and that it works on them but that it doesn't work for just Windows 7?

**Melawe** · August 30th, 2012, 01:20 PM

Yes it uses the JNA library. No I didn't get to test it. I use Ubuntu and don't have win available atm.

**newbie** · August 30th, 2012, 01:22 PM

If you're trying to use Windows libraries on Ubuntu and it doesn't work, then that is your problem ;p

**Melawe** · August 30th, 2012, 03:18 PM

Lol no. I'm coding it for windows, on an Ubuntu based platform. The client(a friend, also a programmer) tests it, but it wont work on his win7 based pc.

**curmudgeon** · August 30th, 2012, 05:15 PM

Where did you get this code from? I've used JNA quite a bit, but never for hooking the keyboard, and so I'd like to see your source.

**Melawe** · August 30th, 2012, 06:37 PM

I got it from the net, don't have the link anymore, but it was from one of the stackoverflow questions, or a link from there. I can't show you the code since I'll be selling.

**curmudgeon** · August 30th, 2012, 07:15 PM

Originally Posted by Melawe

I got it from the net, don't have the link anymore, but it was from one of the stackoverflow questions, or a link from there. I can't show you the code since I'll be selling.

OK, then I wish you the best of luck.

**Melawe** · August 30th, 2012, 07:46 PM

Originally Posted by curmudgeon

OK, then I wish you the best of luck.

Is there a problem with something I said, or not showing all the sources? If you don't know or want to tell how to do it, that's okay with me. But if there is something came out wrong, I'd like to know.

**jps** · August 30th, 2012, 08:05 PM

Originally Posted by Melawe

Is there a problem with something I said, or not showing all the sources? If you don't know or want to tell how to do it, that's okay with me. But if there is something came out wrong, I'd like to know.

The problem is there is not mch information to go on, Not to mention your description of the problem in the first post,:

but it seams its not working on Win 7.

...does not tell much about what is wrong. What is that supposed to mean?
Nothing happens when the program runs?
The program fails to run?
Was there any error message?

**curmudgeon** · August 30th, 2012, 08:08 PM

Also there's no compilable code provided to run and test. JNA is a very complex subject and there's not much most of us can do with only partial information. But you're declining to show your code base which is your decision and which is OK, but as for me, it limits what I can do.

**Melawe** · August 30th, 2012, 08:21 PM

Originally Posted by jps

The problem is there is not mch information to go on, Not to mention your description of the problem in the first post,:...does not tell much about what is wrong. What is that supposed to mean?
Nothing happens when the program runs?
The program fails to run?
Was there any error message?

The program runs well, no error messages or any other problems, except for the win, alt, and ctrl keys working. I have to switch these three keys off, so when they are pressed, system wont respond to them.

Originally Posted by curmudgeon

Also there's no compilable code provided to run and test. JNA is a very complex subject and there's not much most of us can do with only partial information. But you're declining to show your code base which is your decision and which is OK, but as for me, it limits what I can do.

I'll edit the original message and add more info too it. Apologies for the very little info, up really late and tiered.

**curmudgeon** · August 30th, 2012, 08:46 PM

OK, I looked through your code and the MSDN and can't see any glaring errors though with the caveat that I am no keyboard hook pro, not by any means. I then added a main method to your code:

 
   public static void main(String[] args) {
      blockWindowsKey();
      System.out.println("here 1");
      try {
         Thread.sleep(10*1000);
      } catch (InterruptedException e) {}
      unblockWindowsKey();
      System.out.println("here 2");
   }

And your code worked on my Windows 7 machine: I was unable to use either the left or right windows keys (0x5B and 0x5C codes) for 10 seconds, and then I was able to use them fine.

**curmudgeon** · August 30th, 2012, 09:03 PM

Here's a small example from the JNA source site at GitHub: KeyHook.java

**Melawe** · August 31st, 2012, 10:50 AM

Originally Posted by curmudgeon

OK, I looked through your code and the MSDN and can't see any glaring errors though with the caveat that I am no keyboard hook pro, not by any means. I then added a main method to your code:

 
   public static void main(String[] args) {
      blockWindowsKey();
      System.out.println("here 1");
      try {
         Thread.sleep(10*1000);
      } catch (InterruptedException e) {}
      unblockWindowsKey();
      System.out.println("here 2");
   }

And your code worked on my Windows 7 machine: I was unable to use either the left or right windows keys (0x5B and 0x5C codes) for 10 seconds, and then I was able to use them fine.

Thanks! I'll try that, but shouldn't it work just fine with out a main method?

**curmudgeon** · August 31st, 2012, 11:29 AM

Originally Posted by Melawe

Thanks! I'll try that, but shouldn't it work just fine with out a main method?

The JVM always needs a starting place to initiate the program, so how would your code work if it's never called?

**Melawe** · August 31st, 2012, 05:09 PM

Originally Posted by curmudgeon

The JVM always needs a starting place to initiate the program, so how would your code work if it's never called?

I have one class with a main method(handles gui and sets everything together), and other objects that deal with other things like ignoring certain keys, and popups. I have another class that ignores keys like delete, backspace, enter, its called in the key listener methods and works great. I don't see why I would need a second main method for the keyhook class if it will be called in the main class. If you could explain that, it would be great!

**curmudgeon** · August 31st, 2012, 05:26 PM

Originally Posted by Melawe

I have one class with a main method(handles gui and sets everything together), and other objects that deal with other things like ignoring certain keys, and popups. I have another class that ignores keys like delete, backspace, enter, its called in the key listener methods and works great. I don't see why I would need a second main method for the keyhook class if it will be called in the main class. If you could explain that, it would be great!

I think we have a miscommunication. I was saying as long as you have a main method that calls the appropriate methods of this class, then you're set. Since all I was testing was your posted class, then I must provide a main method with which to test it.

As an aside, many of my non-"main" classes have main methods for testing purposes.

**Melawe** · August 31st, 2012, 05:38 PM

Originally Posted by curmudgeon

I think we have a miscommunication. I was saying as long as you have a main method that calls the appropriate methods of this class, then you're set. Since all I was testing was your posted class, then I must provide a main method with which to test it.

As an aside, many of my non-"main" classes have main methods for testing purposes.

Ah!

Thanks all for your help. Ill report how things go in a day or so, after client tries it.

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