java - 用 Java JNA 编写的 key 监听器。防止多次回调

Question

我使用下面的代码来监听全局按键事件:Win32HookManager.java

import com.sun.jna.Pointer;
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.WinDef.LPARAM;
import com.sun.jna.platform.win32.WinUser;
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;

/** Sample implementation of a low-level keyboard hook on W32. */
public class KeyHook {
    private static volatile boolean quit;
    private static HHOOK hhk;
    private static LowLevelKeyboardProc keyboardHook;

    public static void main(String[] args) {
        final User32 lib = User32.INSTANCE;
        HMODULE hMod = Kernel32.INSTANCE.GetModuleHandle(null);
        keyboardHook = new LowLevelKeyboardProc() {
            @Override
            public LRESULT callback(int nCode, WPARAM wParam, KBDLLHOOKSTRUCT info) {
                if (nCode >= 0) {
                    switch(wParam.intValue()) {
                    case WinUser.WM_KEYUP:
                    case WinUser.WM_KEYDOWN:
                    case WinUser.WM_SYSKEYUP:
                    case WinUser.WM_SYSKEYDOWN:
                        System.err.println("in callback, key=" + info.vkCode);
                        if (info.vkCode == 81) {
                            quit = true;
                        }
                    }
                }

                Pointer ptr = info.getPointer();
                long peer = Pointer.nativeValue(ptr);
                return lib.CallNextHookEx(hhk, nCode, wParam, new LPARAM(peer));
            }
        };
        hhk = lib.SetWindowsHookEx(WinUser.WH_KEYBOARD_LL, keyboardHook, hMod, 0);
        System.out.println("Keyboard hook installed, type anywhere, 'q' to quit");
        new Thread() {
            @Override
            public void run() {
                while (!quit) {
                    try { Thread.sleep(10); } catch(Exception 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);
    }
}

我想知道为什么我们按一次回调键会调用两次，我们如何防止它？这可能吗？这是单次按键的示例。

in callback, key= 70
in callback, key= 70

我不确定我是否有权在该主题中提出另一个问题，但问题是第一个问题结束，我不想创建另一个主题。所以为什么我们得到 keycode=70 而不是 VC_F = 0x0021。有什么办法只得到VC_F代码

VC_F = 0x0021;

Answer 1

程序正在监听几个消息:WM_KEYUP 和 WM_KEYDOWN

您应该只监听 WM_KEYDOWN。

相关问题:Keyboard Input & the Win32 message loop

MSDN 信息:https://msdn.microsoft.com/en-us/library/windows/desktop/ms646280(v=vs.85).aspx

如果您需要更复杂的行为，那么您应该存储一些信息并查看要接收的连续消息。