From Java, capture mouse click and use as hotkey?

Question

For keyboard, I'm using this to capture keyboard inputs: JIntellitype

This works extremely well, but I would also like to capture mouse events (clicks specifically) and use them as global "hotkeys".

Platform is Windows only, language is Java. I would prefer a nice Java package, and hopefully avoid using JNI/JNA calls or Win32 directly (those are fine though if they are in a nice wrapper).

Answer 1

If you want to use JNA, you can use something similar to the following code.

Using JNA 3.3.0 and JNA platform JAR.

More doco on the LowLevelMouseProc function here and the mouse events here.

MouseHook.java:

package jnatest;

import jnatest.WinUserX.LowLevelMouseProc;
import jnatest.WinUserX.MSLLHOOKSTRUCT;

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;
import com.sun.jna.platform.win32.WinUser.HHOOK;
import com.sun.jna.platform.win32.WinUser.MSG;

public class MouseHook
{
    private static volatile boolean quit;
    private static HHOOK hhk;
    private static LowLevelMouseProc mouseHook;

    public static void main(String[] args) 
    {
        System.out.println("Press middle button to quit.");
        final User32 lib = User32.INSTANCE;
        HMODULE hMod = Kernel32.INSTANCE.GetModuleHandle(null);
        mouseHook = new LowLevelMouseProc() 
        {
            public LRESULT callback(int nCode, WPARAM wParam, MSLLHOOKSTRUCT info) 
            {
                if (nCode >= 0) 
                {
                    switch (wParam.intValue())
                    {
                        case WinUserX.WM_LBUTTONDOWN:
                            System.out.println("Left button click at " + info.pt.x + ", " + info.pt.y);
                            break;
                        case WinUserX.WM_LBUTTONUP:
                            System.out.println("Left button release.");
                            break;
                        case WinUserX.WM_MBUTTONDOWN:
                            System.out.println("Middle button.");
                            quit = true;
                            break;
                    }
                }
                return lib.CallNextHookEx(hhk, nCode, wParam, info.getPointer());
            }
        };
        hhk = lib.SetWindowsHookEx(WinUser.WH_MOUSE_LL, mouseHook, hMod, 0);
        new Thread() 
        {
            public void run() 
            {
                while (!quit) 
                {
                    try { Thread.sleep(10); } catch(InterruptedException e) { }
                }
                System.err.println("unhook and exit");
                lib.UnhookWindowsHookEx(hhk);
                System.exit(0);
            }
        }.start();

        // This bit never returns from GetMessage
        int result;
        MSG msg = new MSG();
        while ((result = lib.GetMessage(msg, null, 0, 0)) != 0) 
        {
            if (result == -1) 
            {
                System.err.println("error in get message");
                break;
            }
            else 
            {
                System.err.println("got message");
                lib.TranslateMessage(msg);
                lib.DispatchMessage(msg);
            }
        }
        lib.UnhookWindowsHookEx(hhk);
    }
}        

WinUserX.java:

package jnatest;

import com.sun.jna.Structure;
import com.sun.jna.platform.win32.BaseTSD.ULONG_PTR;
import com.sun.jna.platform.win32.WinDef.LRESULT;
import com.sun.jna.platform.win32.WinDef.WPARAM;
import com.sun.jna.platform.win32.WinUser;

public interface WinUserX extends WinUser
{
    public int WM_LBUTTONDOWN = 0x0201;
    public int WM_LBUTTONUP = 0x0202; 
    public int WM_MOUSEMOVE = 0x0200;
    public int WM_MOUSEWHEEL = 0x020A;
    public int WM_MOUSEHWHEEL = 0x020E;
    public int WM_RBUTTONDOWN = 0x0204;
    public int WM_RBUTTONUP = 0x0205;
    public int WM_MBUTTONDOWN = 0x0207;

    public interface LowLevelMouseProc extends HOOKPROC 
    {
        LRESULT callback(int nCode, WPARAM wParam, MSLLHOOKSTRUCT lParam);
    }

    public class MSLLHOOKSTRUCT extends Structure 
    {
        public POINT pt;
        public int mouseData;
        public int flags;
        public int time;
        public ULONG_PTR dwExtraInfo;
    }
}