如何使用 Key Bindings 而不是 Key Listener？

Question

所以我正在制作一款破砖游戏。我使用按键侦听器让桨移动，但是我得到了一些使用按键绑定的建议。我一直在阅读和到处寻找这个，我想我有点明白了，但实施让我有点困惑。

对于我的球拍，我是用 paint 组件创建的。因此，这就是我希望能够使用箭头键左右移动的内容。但是，我发现的所有键绑定解释似乎都使用了 JComponent，而桨不是。有没有办法解决这个问题，还是我必须让我的桨变成一个 JComponent 图像图标？如果是这样，我可以将图像加载到我的 Paddle class 吗？

此外，构建我的代码以包含键绑定的最佳方式是什么？例如，我最好为它创建一个全新的 class ，还是把它放在例如我的游戏面板 class

有什么建议吗？

这是我的一些代码，您可以了解一下：

主要Class:

public class BrickBreakerGameApp {
    public static void main(String[] args) {
        int pw = 500;
        int ph = 900;
        GamePanel gPanel = new GamePanel(pw,ph);
        
        GameFrame gFrame = new GameFrame();
       
        gFrame.getContentPane().add(gPanel); //add game panel to frame
        
      //  gFrame.addKeyListener(gPanel); //adds the key listener for the game panel frame
        
        gFrame.pack();
        gFrame.setVisible(true); //make frame visible
    }
}

游戏框架class:

import java.awt.Dimension;

import javax.swing.ImageIcon;
import javax.swing.JFrame;

public class GameFrame extends JFrame {
    //Global Variables
    public int frameWidth = 500;
    public int frameHeight = 800;
    
    //create constructor
    GameFrame () {
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //so app closes properly
        this.setPreferredSize(new Dimension(frameWidth, frameHeight)); //set frame size
        this.setTitle("Brick Breaker Game");

        ImageIcon icon = new ImageIcon("res/brick-breaker-logo.jpg"); //create image icon
        this.setIconImage(icon.getImage()); //update frame icon

        this.pack();
    }
}

游戏面板Class

import java.awt.Color;
import java.awt.event.*;

import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

import java.awt.*;

/**
 * This class handles the game panel as a whole
 */

public class GamePanel extends JPanel {

    // Global Variables
    private Ball ball;
    private Paddle paddle;
    private Bricks bricks;
    private GameFrame gameFrame;
    private int width;
    private int height;
    private int[] bArray = new int[20];

    // create a constructor
    GamePanel (int gamePanelWidth, int gamePanelHeight) {
    

        this.setWidth(gamePanelWidth);
        this.setHeight(gamePanelHeight);
        
        
        
        initialiseGame();
        this.isVisible();
        
    }


    private void initialiseGame() {
        ball = new Ball(10, 520, 30, 30); //create the ball object
        paddle = new Paddle(this, 50, 700, 100, 10); //creates paddle object
        bricks = new Bricks(10, 10, 60, 30, bArray); //creates the bricks object

        //for key binding initialisation
        MotionAction motion = new MotionAction(paddle, 24);
        
    }

    
    // paint all the elements in
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        // background
        g.setColor(Color.black);
        g.fillRect(0, 0, getWidth(), getHeight());

        // paddle
     //   g.setColor(Color.CYAN);
     //   g.fillRect(paddle.getPaddleX(), paddle.getPaddleY(), paddle.getPaddleWidth(), paddle.getPaddleHeight());

        // ball
        g.setColor(Color.MAGENTA);
        g.fillOval(ball.getBallX(), ball.getBallY(), ball.getBallWidth(), ball.getBallHeight());

        // brick
        g.setColor(Color.GREEN);
        g.fillRect(bricks.getBrickX(), bricks.getBrickY(), bricks.getBrickWidth(), bricks.getBrickHeight());

    }

    //add any unimplemented methods because we are using an interface
 /*   @Override
    public void actionPerformed(ActionEvent e) {
        
    }

    @Override
    public void keyPressed(KeyEvent e) {
        

        if(e.getKeyCode() == KeyEvent.VK_LEFT) {
            paddle.moveLeft();
            
    
        }
        if(e.getKeyCode() == KeyEvent.VK_RIGHT) {
            paddle.moveRight();
            
        }
        this.repaint();
        
        
    }


 
    
    




    @Override
    public void keyTyped(KeyEvent e) {  
    }
    
    @Override
    public void keyReleased(KeyEvent e) {   
    } */
    
    
    
    //create get and set methods for all panel attributes
    public int getWidth() {
        return width;
    }

    public void setWidth(int pWidth) {
        this.width = pWidth;
    }

    public int getHeight() {
        return height;
    }

    public void setHeight(int pHeight) {
        this.height = pHeight;
    }

    
}

桨 class:

import javax.swing.AbstractAction;

import java.awt.event.*;

public class Paddle extends AbstractAction implements ActionListener {
    //Global Variables
    private int paddleWidth;
    private int paddleHeight;
    private int paddleX; //paddle x position
    private int paddleY;
    private GamePanel gamePanel;
    
    //create paddle constructor
    Paddle() {

    }

    //create a paddle constructor based off parameters
    Paddle(GamePanel gPanel, int pX, int pY, int pWidth, int pHeight) {
        //set the values
        this.setPaddleWidth(pWidth);
        this.setPaddleHeight(pHeight);
        this.setPaddleX(pX);
        this.setPaddleY(pY);
        this.setGamePanel(gPanel);

    }

    //create get and set methods for all paddle attributes
    public int getPaddleWidth() {
        return paddleWidth;
    }

    public void setPaddleWidth(int pWidth) {
        this.paddleWidth = pWidth;
    }

    public int getPaddleHeight() {
        return paddleHeight;
    }

    public void setPaddleHeight(int pHeight) {
        this.paddleHeight = pHeight;
    }

    public int getPaddleX() {
        return paddleX;
    }

    public void setPaddleX(int pX) {
        this.paddleX = pX;
    }

    public int getPaddleY() {
        return paddleY;
    }

    public void setPaddleY(int pY) {
        this.paddleY = pY;
    }

    
    public GamePanel getGamePanel() {
        return gamePanel;
    }

    public void setGamePanel(GamePanel gPanel) {
        this.gamePanel = gPanel;
    }

    //move the paddle left if it is not already positoned at 0 (far left)
    public void moveLeft() {
        try {
            if(getPaddleX() <= 0) {
                setPaddleX(0);
                System.out.println("less than 0, x: " + getPaddleX());
                
            } 
            else if (getPaddleX() > 0) {
                setPaddleX(getPaddleX()-10); //to move paddle left -10
          //      gamePanel.repaint(getPaddleX()+10, getPaddleY(), getPaddleWidth(), getPaddleHeight()); //repaint old position
          //      gamePanel.repaint(getPaddleX(), getPaddleY(), getPaddleWidth(), getPaddleHeight()); //repaint new position
                System.out.println("left, x: " + getPaddleX());
              
            }
            
            
        }
        catch (Exception e) {
            
         }
        

    }

    

    //move the paddle right if it is not already positioned to the far right of the panel
    public void moveRight() {
        
        if(getPaddleX() >= gamePanel.getWidth() - getPaddleWidth()) { //dont move the paddle if it is on the right edge of the panel
            setPaddleX(gamePanel.getWidth() - getPaddleWidth());
            System.out.println("right1, x:" + getPaddleX());
            
        }
        else if ((getPaddleX()+getPaddleWidth()) <= gamePanel.getWidth()){ //if the paddle is within the panel bounds
            setPaddleX(getPaddleX() + 10); //to move paddle right +10
            System.out.println("right, x:" + getPaddleX());
        }
        
    }
}

以下是我尝试使用的一些主要资源：这个我试过了，但对将它集成到我自己的代码中的最佳方式感到非常困惑 --> https://tips4java.wordpress.com/2013/06/09/motion-using-the-keyboard/

这个我试过了，直到我意识到我没有 jcomponent --> https://coderanch.com/t/606742/java/key-bindings

Answer 1

您可以向 GamePanel 或框架内容窗格（均从 JComponent 扩展）注册键绑定。例如：

public class DemoFrame extends JFrame {
  public static void main(String[] args) throws Exception {
    new DemoFrame().setVisible(true);
  }

  public DemoFrame() {
    setSize(800, 600);
    setLocationRelativeTo(null);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    {
      String actionId = "left";
      KeyStroke keyStroke = KeyStroke.getKeyStroke("LEFT");
      getRootPane().getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(keyStroke, actionId);
      getRootPane().getActionMap().put(actionId, new AbstractAction() {
        @Override
        public void actionPerformed(ActionEvent e) {
          actionLeft();
        }
      });
    }
  }

  private void actionLeft() {
    System.out.println("left");
  }
}

如何使用 Key Bindings 而不是 Key Listener？

How to use Key Bindings instead of Key Listener?

java

swing

jcomponent

keylistener

key-bindings