java - 如何将 WASD 键连接到特定事件？

Question

我对编程还很陌生，但我很好奇并且想了解更多。目前，我正在尝试制作一个非常简单的程序，可以在屏幕上移动二维球。然而，目前我必须使用程序中的按钮来移动球。我希望能够使用 WASD 之类的。我已经搜索过这个网站，但没有找到足够基本的东西。我的问题实际上很简单 - 当我按下一个键(例如 W)时，如何才能使球朝那个方向移动(或我添加到其中的任何事件)？我在这个网站上看到了类似的内容: ( g.getKeyCode() == KeyEvent.VK_LEFT)

但是，上述代码无法使球移动。是否有任何简单的代码可以连接按下的键和事件？请注意，我使用 NetBeans。

下面，您可以看到我正在尝试使用的内容(以及不起作用的内容)的描述:

编辑:为了澄清这一点，这里是我正在使用的整个代码，作为示例:

    package gamePanel;
    import java.awt.Color;
    import java.awt.Graphics;

    public class GamePanel extends javax.swing.JPanel {


public GamePanel() {
    initComponents();
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    btnUp = new javax.swing.JButton();
    btnDown = new javax.swing.JButton();
    btnLeft = new javax.swing.JButton();
    btnRight = new javax.swing.JButton();

    btnUp.setText("Up");
    btnUp.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnUpActionPerformed(evt);
        }
    });

    btnDown.setText("Down");
    btnDown.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnDownActionPerformed(evt);
        }
    });

    btnLeft.setBackground(new java.awt.Color(140, 140, 140));
    btnLeft.setText("Left");
    btnLeft.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnLeftActionPerformed(evt);
        }
    });

    btnRight.setBackground(new java.awt.Color(140, 140, 140));
    btnRight.setText("Right");
    btnRight.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            btnRightActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
    this.setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(84, 84, 84)
            .addComponent(btnLeft, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(btnUp, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(btnDown, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(btnRight)
            .addContainerGap(129, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
            .addContainerGap(238, Short.MAX_VALUE)
            .addComponent(btnUp)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(btnDown)
                .addComponent(btnLeft)
                .addComponent(btnRight))
            .addGap(10, 10, 10))
    );
}// </editor-fold>                        

int x = 0;
int y = 0;

private void btnUpActionPerformed(java.awt.event.ActionEvent evt) {                                      

    y -= 10;
    repaint();
}                                     

private void btnDownActionPerformed(java.awt.event.ActionEvent evt) {                                        

    y += 10;
    repaint();
}                                       

private void btnLeftActionPerformed(java.awt.event.ActionEvent evt) {                                        

    x -= 10;
    repaint();
}                                       

private void btnRightActionPerformed(java.awt.event.ActionEvent evt) {                                         

    x += 10;
    repaint();
}                                        

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

    g.setColor(Color.BLACK);
    g.fillOval(x, y, 25, 25);
}


// Variables declaration - do not modify                     
private javax.swing.JButton btnDown;
private javax.swing.JButton btnLeft;
private javax.swing.JButton btnRight;
private javax.swing.JButton btnUp;
// End of variables declaration                   

}

Answer 1

使用按键绑定(bind)。这是我的一个 Swing 应用程序中的方法。我将这些键绑定(bind)到 JPanel (gridPanel)，但您可以将它们绑定(bind)到您想要的任何 Swing 组件。

private void setKeyBindings() {
    InputMap inputMap = 
            gridPanel.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW);
    inputMap.put(KeyStroke.getKeyStroke("W"), "up arrow");
    inputMap.put(KeyStroke.getKeyStroke("S"), "down arrow");
    inputMap.put(KeyStroke.getKeyStroke("A"), "left arrow");
    inputMap.put(KeyStroke.getKeyStroke("D"), "right arrow");

    inputMap.put(KeyStroke.getKeyStroke("UP"), "up arrow");
    inputMap.put(KeyStroke.getKeyStroke("DOWN"), "down arrow");
    inputMap.put(KeyStroke.getKeyStroke("LEFT"), "left arrow");
    inputMap.put(KeyStroke.getKeyStroke("RIGHT"), "right arrow");

    inputMap = gridPanel.getInputMap(JPanel.WHEN_FOCUSED);
    inputMap.put(KeyStroke.getKeyStroke("UP"), "up arrow");
    inputMap.put(KeyStroke.getKeyStroke("DOWN"), "down arrow");
    inputMap.put(KeyStroke.getKeyStroke("LEFT"), "left arrow");
    inputMap.put(KeyStroke.getKeyStroke("RIGHT"), "right arrow");


    gridPanel.getActionMap().put("up arrow", 
            new UpArrowAction(this, model));
    gridPanel.getActionMap().put("down arrow", 
            new DownArrowAction(this, model));
    gridPanel.getActionMap().put("left arrow", 
            new LeftArrowAction(this, model));
    gridPanel.getActionMap().put("right arrow", 
            new RightArrowAction(this, model));
}

整个 Java Swing 应用程序可以在我的 2048 Game in Java Swing 中找到文章。