java - KeyListener 不工作(requestFocus 没有修复它)

Question

我正在尝试在没有 YouTube 视频帮助的情况下制作我的第一款游戏。我看过很多关于制作 java 游戏的 youtube 系列，但它们从来没有出现在我想做的地方，所以在学习足够多之后，我开始制作自己的游戏。我对 Java 有足够的了解，到目前为止，一切都没有问题。

我曾尝试寻求一些帮助，但我只能找到人们说尝试以下内容的地方:

setFocusable(true);
requestFocus();

然而，这对我不起作用。我知道大多数人不喜欢只浏览我的所有代码，但我认为它是易于管理的(代码还不是那么多)。

我打算把它做成一种蛇类游戏，你会变大而不是变长，你是一只豚鼠(现在用橙色矩形表示)而不是蛇。

游戏.java:

package com.kaperly.game;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.IOException;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Game extends JFrame {
    private static final long serialVersionUID = 1L;

    public static JFrame frame;
    public static JPanel panel;

    public static int width = 1000;
    public static int height = 600;

    public Game() {
        frame = new JFrame();
        panel = new Panel();

        frame.setPreferredSize(new Dimension(width, height));
        frame.setResizable(false);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Guinea Pig Eat");
        frame.setLayout(new BorderLayout());
        frame.setVisible(true);
        panel.setFocusable(true);
        panel.requestFocus(true);

        frame.add(panel, BorderLayout.CENTER);
        frame.pack();
    }

    public static void init() {

    }

    public static void loop() throws InterruptedException { while(true) {
        Character.move();

        Thread.sleep(10);
    }}

    public static void main(String[] args) throws InterruptedException, IOException {
        Game game = new Game();

        init();
        loop();
    }
}

面板.java:

package com.kaperly.game;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JPanel;

public class Panel extends JPanel implements KeyListener {
    private static final long serialVersionUID = 1L;

    public static Image startButton;

    public static boolean goingRight = false;
    public static boolean goingLeft = false;
    public static boolean goingUp = false;
    public static boolean goingDown = false;

    private static int changeDirection = 0;

    @Override
    public void keyPressed(KeyEvent e) {
        if(e.getKeyCode() == KeyEvent.VK_W) {
            goingUp = true;
            changeDirection = 1;
            System.out.println("Moved Up!");

        }else if(e.getKeyCode() == KeyEvent.VK_A) {
            goingLeft = true;
            changeDirection = 2;

        }else if(e.getKeyCode() == KeyEvent.VK_S) {
            goingDown = true;
            changeDirection = 3;

        }else if(e.getKeyCode() == KeyEvent.VK_D) {
            goingRight = true;
            changeDirection = 4;

        }else if(changeDirection == (1 | 2 | 3 | 4)) {
            changeDirection = 0;
            if(changeDirection == 1) {
                goingLeft = false;
                goingDown = false;
                goingRight = false;

            }else if(changeDirection == 2) {
                goingUp = false;
                goingDown = false;
                goingRight = false;

            }else if(changeDirection == 3) {
                goingUp = false;
                goingLeft = false;
                goingRight = false;

            }else if(changeDirection == 4) {
                goingUp = false;
                goingLeft = false;
                goingDown = false;
            }
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {

    }

    @Override
    public void keyTyped(KeyEvent e) {

    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        //Set background color
        g.setColor(Color.GRAY);
        g.fillRect(0, 0, Game.width, Game.height);


        //Make Walls
        g.setColor(Color.BLACK);
        g.fillRect(0, 0, Game.width, 25);
        g.fillRect(0, 550, Game.width, 25);
        g.fillRect(0, 0, 25, Game.height);
        g.fillRect(970, 0, 25, Game.height);

        //Show Character
        g.setColor(Color.ORANGE);
        g.fillRect(Character.x, Character.y, Character.width, Character.height);

        repaint();
    }
}

字符.java:

package com.kaperly.game;

public class Character {

    public static int x = 475;
    public static int y = 250;

    public static int width = 50;
    public static int height = 75;

    public static void move() {
        if(Panel.goingUp == true) {
            y = y ++;
        }
        if(Panel.goingLeft == true) {
            x = x --;
        }
        if(Panel.goingDown == true) {
            y = y --;
        }
        if(Panel.goingRight == true) {
            x = x ++;
        }
    }
}

Answer 1

KeyListener 应该避免，因为它存在与焦点相关的固有问题。您永远不知道什么可能会将键盘焦点从您的组件上移开。

相反，利用 Key Bindings API，它允许您控制触发关键事件所需的焦点级别。

它还允许您在其他地方重用与键绑定(bind)关联的底层 Action...

您最好将类 Panel 重命名为更有意义的名称。 AWT 已经有一个 Panel 类，很容易混淆这两者