java - JNativeHook (GlobalScreen) 不使用 switch 和 if 语句

Question

我正在创建一个简单的工具来检索当前的鼠标坐标，以帮助我编写 future 的项目。我决定不下载一个，因为我想作为一名自学成才的程序员扩展我的知识。

我将 JNativeHook 用作 NetBeans 中的库，以在 JFrame 未获得焦点时帮助我使用 KeyListeners。我研究和调试了几个小时，发现 KeyReleased 方法不适用于 if 和 switch 语句。它检测到 KeyRelease，因为我将 System.out.println(); 放在方法中；它打印出来了。我的代码在下面。

package Main;

import java.awt.MouseInfo;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.StringSelection;
import java.util.logging.LogManager;
import javax.swing.*;
import org.jnativehook.GlobalScreen;
import org.jnativehook.NativeHookException;
import org.jnativehook.dispatcher.SwingDispatchService;
import org.jnativehook.keyboard.NativeKeyEvent;
import org.jnativehook.keyboard.NativeKeyListener;

public class MainClass implements NativeKeyListener {

    static JFrame frame;
    static JLabel label;
    static JPanel panel;
    static boolean run = true; //pause variable

    private static void jframe(){ //JFrame code
        frame = new JFrame("Mouse Coordinates");    
        label = new JLabel();
        panel = new JPanel();
        frame.setUndecorated(true);
        frame.setVisible(true);
        frame.setResizable(false);
        frame.setAlwaysOnTop(true);

        panel.add(label);
        frame.add(panel);
        frame.pack();
    }

    private static void check(){ //updating label text
        if(run){ //if not paused
            new Thread(new Runnable() {
                @Override
                public void run() {
                    while(run){ //loop
                        label.setText(MouseInfo.getPointerInfo().getLocation().toString().replaceAll("java.awt.Point", "")); 
                        frame.setSize(label.getWidth() + 5, label.getHeight() + 5); //Adapt frame size to fit label
                    }
                }
            }).start();
        }
    }

    public void nativeKeyPressed(NativeKeyEvent e) {

    }

    public void nativeKeyReleased(NativeKeyEvent e) {
        switch(e.getKeyCode()){
            case 27: //close code (esc key)
                System.exit(0);
            case 80: //pause code (p key)
                run = !run;
                check();
            case 67: //copy code (c key)
                StringSelection ss = new StringSelection(MouseInfo.getPointerInfo().getLocation().toString().replaceAll("java.awt.Point", "").replaceAll("\\[", "").replaceAll("\\]", "").replaceAll("=", "").replaceAll("x", "").replaceAll("y", "").replaceAll(",", ", ")); //get mouse coordinates and set them as a StringSelection
                Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard(); //get the clipboard
                cb.setContents(ss, ss); //set what is copied to the current mouse coordinates
            break;
        }
    }

    public void nativeKeyTyped(NativeKeyEvent e) {

    }

    public static void main(String[] args){

        LogManager.getLogManager().reset(); //stop the annoying constant logging of GlobalScreen

        try {
            GlobalScreen.setEventDispatcher(new SwingDispatchService());
            GlobalScreen.registerNativeHook();
        } catch (NativeHookException ex) {
            System.err.println("There was a problem registering the native hook.");
            System.err.println(ex.getMessage());

            System.exit(1);
        }

        GlobalScreen.addNativeKeyListener(new MainClass());

        jframe(); //Run JFrame code
        check(); //Run check code

        SwingUtilities.invokeLater(new Runnable() { 
            @Override
            public void run() {
                new MainClass();
            }
        });
    }  
}

感谢任何帮助重新使用 JNativeHook 的 switch 语句!

Answer 1

这段代码解决了你的问题。

1. 我认为主要问题出在 e.getKeyCode() 上因为它不会在 nativeKeyPressed 上返回相同的值和 nativeKeyReleased所以我把你的代码放在方法中 public void nativeKeyPressed(NativeKeyEvent e)

2. 我还添加了一些注释以直观地指示您按的是哪个键。

3. 为了避免“魔数(Magic Number)”(27、87、67 谁能猜出是什么意思？)我将其转换为字符串形式，我认为代码的可读性有所提高。

4. 我把 break;每个 case block 末尾的指令，如果您不放置，代码将遍历所有 case。

   public void nativeKeyPressed(NativeKeyEvent e) {
       String keyText = NativeKeyEvent.getKeyText(e.getKeyCode());
       switch(keyText){
       case "Escape": //close code (esc key)
           System.out.println("Pressed esc");
           System.exit(0);
           break;
       case "P": //pause code (p key)
           System.out.println("Pressed p");
           run = !run;
           check();
           break;
       case "C": //copy code (c key)
           System.out.println("Pressed c");
           StringSelection ss = new StringSelection(MouseInfo.getPointerInfo().getLocation().toString().replaceAll("java.awt.Point", "").replaceAll("\\[", "").replaceAll("\\]", "").replaceAll("=", "").replaceAll("x", "").replaceAll("y", "").replaceAll(",", ", ")); //get mouse coordinates and set them as a StringSelection
           Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard(); //get the clipboard
           cb.setContents(ss, ss); //set what is copied to the current mouse coordinates
           break;
       }
   }
   
   public void nativeKeyReleased(NativeKeyEvent e) {
   
   }