ActionListener无法在某些计算机上运行？

Question

我正在制作一个蛇游戏，它可以在我的电脑上正常工作，但不适用于任何学校的电脑。它编译，我可以运行它，但我的按键事件不起作用，所以我无法控制蛇，因为键不起作用。

蛇类

import java.awt.Dimension;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.Timer;

public class Snake implements ActionListener, KeyListener 
{

    public static Snake snake;

    public JFrame jframe;

    public RenderPanel renderPanel;

    public Timer timer = new Timer(20, this);

    public ArrayList<Point> snakeParts = new ArrayList<Point>();

    public static final int UP = 0, DOWN = 1, LEFT = 2, RIGHT = 3, SCALE = 10;

    public int ticks = 0, direction = DOWN, score, tailLength = 10, time;

    public Point head, mouse;

    public Random random;

    public boolean over = false, paused;

    public Dimension dim;

    public Snake() 
    {
        dim = Toolkit.getDefaultToolkit().getScreenSize();
        jframe = new JFrame("TechnoSnake");
        jframe.setVisible(true);
        jframe.setSize(805, 700);
        jframe.setResizable(false);
        jframe.setLocation(dim.width / 2 - jframe.getWidth() / 2, dim.height / 2 - jframe.getHeight() / 2);
        jframe.add(renderPanel = new RenderPanel());
        jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jframe.addKeyListener(this);
        startGame();
    }

    public void startGame() 
    {
        over = false;
        paused = false;
        time = 0;
        score = 0;
        tailLength = 1;
        ticks = 0;
        direction = DOWN;
        head = new Point(0, -1);
        random = new Random();
        snakeParts.clear();
        mouse = new Point(random.nextInt(79), random.nextInt(66));
        timer.start();
    }

    public void actionPerformed(ActionEvent arg0) 
    {
        renderPanel.repaint();
        ticks++;
        if (ticks % 2 == 0 && head != null && !over && !paused) 
        {
            time++;
            snakeParts.add(new Point(head.x, head.y));
            if (direction == UP)
                if (head.y - 1 >= 0 && noTailAt(head.x, head.y - 1)) 
                    head = new Point(head.x, head.y - 1);
                else
                    over = true;
            if (direction == DOWN)
                if (head.y + 1 < 67 && noTailAt(head.x, head.y + 1))
                    head = new Point(head.x, head.y + 1);
                else
                    over = true;
            if (direction == LEFT)
                if (head.x - 1 >= 0 && noTailAt(head.x - 1, head.y))
                    head = new Point(head.x - 1, head.y);
                else
                    over = true;
            if (direction == RIGHT)
                if (head.x + 1 < 80 && noTailAt(head.x + 1, head.y))
                    head = new Point(head.x + 1, head.y);
                else
                    over = true;
            if (snakeParts.size() > tailLength)
                snakeParts.remove(0);
            if (mouse != null) 
            {
                if (head.equals(mouse)) 
                {
                    score += 10;
                    tailLength++;
                    mouse.setLocation(random.nextInt(79), random.nextInt(66));
                }
            }
        }
    }

    public boolean noTailAt(int x, int y) 
    {
        for (Point point : snakeParts) 
        {
            if (point.equals(new Point(x, y))) 
            {
                return false;
            }
        }
        return true;
    }

    public static void main(String[] args) 
    {
        snake = new Snake();
    }

    public void keyPressed(KeyEvent e)
    { 
        int i = e.getKeyCode();
        if ((i == KeyEvent.VK_A || i == KeyEvent.VK_LEFT)  && direction != RIGHT)
            direction = LEFT;
        if ((i == KeyEvent.VK_D || i == KeyEvent.VK_RIGHT) && direction != LEFT)
            direction = RIGHT;
        if ((i == KeyEvent.VK_W || i == KeyEvent.VK_UP)  && direction != DOWN)
            direction = UP;
        if ((i == KeyEvent.VK_S || i == KeyEvent.VK_DOWN) && direction != UP)
            direction = DOWN;
        if (i == KeyEvent.VK_SPACE)
            if (over)
                startGame();
            else
                paused = !paused;
    }

    public void keyReleased(KeyEvent e) 
    {

    }


    public void keyTyped(KeyEvent e) 
    {

    }

}

RenderPanel Class

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;

import javax.swing.JPanel;

public class RenderPanel extends JPanel 
{
    //public static Color green = new Color(1666073);
    public static Color brown = new Color(6697728);

    protected void paintComponent(Graphics g) 
    {
        super.paintComponent(g);
        //g.setColor(green);
        g.setColor(Color.BLACK);
        g.fillRect(0, 0, 800, 700);
        Snake snake = Snake.snake;
        g.setColor(Color.BLUE);
        for (Point point : snake.snakeParts) 
        {
            g.fillRect(point.x * Snake.SCALE, point.y * Snake.SCALE, Snake.SCALE, Snake.SCALE);
        }
        g.fillRect(snake.head.x * Snake.SCALE, snake.head.y * Snake.SCALE, Snake.SCALE, Snake.SCALE);
        g.setColor(Color.RED);
        g.fillRect(snake.mouse.x * Snake.SCALE, snake.mouse.y * Snake.SCALE, Snake.SCALE, Snake.SCALE);
        String string = "Score: " + snake.score + ", Length: " + snake.tailLength + ", Time: " + snake.time / 20;
        g.setColor(Color.white);
        g.drawString(string, (int) (getWidth() / 2 - string.length() * 2.5f), 10);
        string = "Game Over!";
        if (snake.over)
            g.drawString(string, (int) (getWidth() / 2 - string.length() * 2.5f), (int) snake.dim.getHeight() / 4);
        string = "Paused!";
        if (snake.paused && !snake.over)
            g.drawString(string, (int) (getWidth() / 2 - string.length() * 2.5f), (int) snake.dim.getHeight() / 4);
    }
}

Answer 1

你真的不应该向KeyListener添加JFrame。 JFrame由框架JRootPane组成，其中包含内容窗格（现在是您的RenderPanel），并且可能还有一个玻璃窗格。所有这些都可以将焦点从框架中移开，这意味着它永远无法响应关键事件

KeyListener只会在注册的组件具有焦点并且具有焦点时才会引发关键事件。

请尝试使用key bindings。它们可以更好地控制生成关键事件所需的焦点水平