JNA在Windows中的键盘钩子

Question

我已经用JNA创建了一个安装Windows键盘钩子的代码（使用了JNA的示例）。 代码编译和运行都没有问题，我成功安装了钩子（获得钩子句柄），而且我可以成功卸载钩子。 但是，当我按下键盘上的任何键时，回调函数从未被调用。 这是我的代码（大部分是从JNA示例中获取的类型定义，请直接转到“main”查看我的部分）。

import com.sun.jna.IntegerType;
import com.sun.jna.Pointer;
import com.sun.jna.PointerType;
import com.sun.jna.Structure;
import com.sun.jna.FromNativeContext;
import com.sun.jna.ptr.IntByReference;
import com.sun.jna.ptr.PointerByReference;
import com.sun.jna.win32.StdCallLibrary;
import com.sun.jna.win32.StdCallLibrary.StdCallCallback;
import com.sun.jna.Native;
import com.sun.jna.Platform;
import com.sun.jna.Library;
import com.sun.jna.win32.W32APITypeMapper;
import com.sun.jna.win32.W32APIFunctionMapper;

import java.util.Map;
import java.util.HashMap;

public class HelloWorld {
    static Map UNICODE_OPTIONS = new HashMap() {
        {
            put("type-mapper", W32APITypeMapper.UNICODE);
            put("function-mapper", W32APIFunctionMapper.UNICODE);
        }
    };

    public static class LONG_PTR extends IntegerType {
        public LONG_PTR() { this(0); }
        public LONG_PTR(long value) { super(Pointer.SIZE, value); }
    }

    public static class UINT_PTR extends IntegerType {
        public UINT_PTR() { super(Pointer.SIZE); }
        public UINT_PTR(long value) { super(Pointer.SIZE, value); }
        public Pointer toPointer() { return Pointer.createConstant(longValue()); }
    }

    public static class ULONG_PTR extends IntegerType {
        public ULONG_PTR() { this(0); }
        public ULONG_PTR(long value) { super(Pointer.SIZE, value); }
    }

    public static class LRESULT extends LONG_PTR {
        public LRESULT() { this(0); }
        public LRESULT(long value) { super(value); }
    }

    public static class WPARAM extends UINT_PTR {
        public WPARAM() { this(0); }
        public WPARAM(long value) { super(value); }
    }

    public static class LPARAM extends LONG_PTR {
        public LPARAM() { this(0); }
        public LPARAM(long value) { super(value); }
    }

    public static class KBDLLHOOKSTRUCT extends Structure {
        public int vkCode;
        public int scanCode;
        public int flags;
        public int time;
        public ULONG_PTR dwExtraInfo;
    }

    static HANDLE INVALID_HANDLE_VALUE = new HANDLE() {
        { super.setPointer(Pointer.createConstant(-1)); }
        public void setPointer(Pointer p) {
            throw new UnsupportedOperationException("Immutable reference");
        }
    };

    public static class HANDLE extends PointerType {
        public Object fromNative(Object nativeValue, FromNativeContext context) {
            Object o = super.fromNative(nativeValue, context);
            if (INVALID_HANDLE_VALUE.equals(o))
                return INVALID_HANDLE_VALUE;
            return o;
        }
    }

    public static class HHOOK extends HANDLE { }
    public static class HINSTANCE extends HANDLE { }
    public static class HMODULE extends HINSTANCE { }

    public interface User32 extends StdCallLibrary  {
        User32 INSTANCE = (User32)Native.loadLibrary("user32", User32.class, UNICODE_OPTIONS);

        static final int WH_KEYBOARD_LL = 13;

        public static interface HOOKPROC extends StdCallCallback  {
            LRESULT callback(int nCode, WPARAM wParam, KBDLLHOOKSTRUCT lParam);
        }

        HHOOK SetWindowsHookEx(int idHook, HOOKPROC lpfn, HMODULE hMod, int dwThreadId);
        LRESULT CallNextHookEx(HHOOK idHook, int nCode, WPARAM wParam, LPARAM lParam);
        LRESULT CallNextHookEx(HHOOK idHook, int nCode, WPARAM wParam, Pointer lParam);

        boolean UnhookWindowsHookEx(HHOOK idHook);
    }

    public interface Kernel32 extends StdCallLibrary {
        Kernel32 INSTANCE = (Kernel32)Native.loadLibrary("kernel32", Kernel32.class, UNICODE_OPTIONS);

        HMODULE GetModuleHandle(String name);
    }

    public static HHOOK hHook;
    public static User32.HOOKPROC lpfn;
    public static volatile boolean quit = false;

    public static void main(String[] args) throws Exception {
        HMODULE hMod = Kernel32.INSTANCE.GetModuleHandle(null);
        System.out.println(hMod);

        lpfn = new User32.HOOKPROC() {
            public LRESULT callback(int nCode, WPARAM wParam, KBDLLHOOKSTRUCT lParam) {
                System.out.println("here");
                quit = true;
                return User32.INSTANCE.CallNextHookEx(hHook, nCode, wParam, lParam.getPointer());
            }
        };

        hHook = User32.INSTANCE.SetWindowsHookEx(User32.WH_KEYBOARD_LL, lpfn, hMod, 0);
        System.out.println(hHook);

        if(hHook != null)
            System.out.println("Keyboard hooked, type anything to quit");

        while(!quit) {
            Thread.sleep(100);
        }

        if(User32.INSTANCE.UnhookWindowsHookEx(hHook))
            System.out.println("Unhooked");

    }
}

我之前用过C++和C#多次完成键盘/鼠标钩子。这是我第一次尝试使用Java，我不确定我是否正确导入和映射了库文件。有什么建议吗？

谢谢。

- temp

Answer 1

看起来你需要调用 GetMessage 或者 PeekMessage，这很奇怪——在Hooks或LowLevelKeyboardProc文档中都没有提到它。我对此API的了解不够深入，无法猜测原因。

我只是使用了示例类：

import com.sun.jna.examples.win32.*;

public class Callback {
  public static User32.HHOOK hHook;
  public static User32.LowLevelKeyboardProc lpfn;
  public static volatile boolean quit = false;

  public static void main(String[] args) throws Exception {
    W32API.HMODULE hMod = Kernel32.INSTANCE.GetModuleHandle(null);
    lpfn = new User32.LowLevelKeyboardProc() {
      public W32API.LRESULT callback(int nCode, W32API.WPARAM wParam,
          User32.KBDLLHOOKSTRUCT lParam) {
        System.out.println("here");
        quit = true;
        return User32.INSTANCE.CallNextHookEx(hHook, nCode, wParam, lParam
            .getPointer());
      }
    };
    hHook = User32.INSTANCE.SetWindowsHookEx(User32.WH_KEYBOARD_LL, lpfn, hMod,
        0);
    if (hHook == null)
      return;
    User32.MSG msg = new User32.MSG();
    while (!quit) {
      User32.INSTANCE.PeekMessage(msg, null, 0, 0, 0);
      Thread.sleep(100);
    }
    if (User32.INSTANCE.UnhookWindowsHookEx(hHook))
      System.out.println("Unhooked");
  }
}

- McDowell

---

看到另一个使用GetMessage/DispatchMessage的例子，虽然从未想过它与键盘钩子本身有任何关系（我在C++/C#中从未需要它们）。非常感谢您的帮助McDowell，我又恢复了理智 :) - temp

如何获取com.sun.jna.examples.win32？我在jna.jar或platform.jar中都找不到它。请告诉我。谢谢。 - Qiang Li

@Qiang Li - 我是根据JNA 3.0.9编写的这段代码；示例类在examples.jar中。 - McDowell

Answer 2

一个极简的例子：

import com.sun.jna.platform.win32.Kernel32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HINSTANCE;
import com.sun.jna.platform.win32.WinDef.LPARAM;
import com.sun.jna.platform.win32.WinDef.LRESULT;
import com.sun.jna.platform.win32.WinDef.WPARAM;
import com.sun.jna.platform.win32.WinUser.HOOKPROC;

public class MainTestKeyHook {


    public static void main(String[] args) throws Exception {
        HOOKPROC hookProc = new HOOKPROC_bg();
        HINSTANCE hInst = Kernel32.INSTANCE.GetModuleHandle(null);

        User32.HHOOK hHook = User32.INSTANCE.SetWindowsHookEx(User32.WH_KEYBOARD_LL, hookProc, hInst, 0);
        if (hHook == null)
            return;
        User32.MSG msg = new User32.MSG();
        System.err.println("Please press any key ....");
        while (true) {
            User32.INSTANCE.GetMessage(msg, null, 0, 0);
        }   
    }
}

class HOOKPROC_bg implements HOOKPROC {

    public HOOKPROC_bg() {
    }

    public LRESULT callback(int nCode, WPARAM wParam, LPARAM lParam) {
        System.err.println("callback bbbnhkilhjkibh nCode: " + nCode);
        return new LRESULT(0);
    }
}

- Bertrand