如何在java中输入键盘后更改图像？

我有以下代码向您展示：

public class Test extends JPanel implements ActionListener, KeyListener { Timer tm = new Timer(5, this); int x = 0, y = 0, velX = 0, velY = 0; public Test() { tm.start(); //starts the timer addKeyListener(this); setFocusable(true); setFocusTraversalKeysEnabled(false); } public void paint(Graphics g) { super.paint(g); ImageIcon s = new ImageIcon("C:\\Users\\Owner\\Pictures\\Stick.jpg"); s.paintIcon(this,g,x,y); } public void actionPerformed(ActionEvent e) { if (x  630) { velX = 0; x = 630; } if(y  430) { velY = 0; y = 430; } x = x + velX; y = y + velY; repaint(); } public void keyPressed(KeyEvent e) { int c = e.getKeyCode(); if (c == KeyEvent.VK_LEFT) { velX = -1; velY = 0; } if(c == KeyEvent.VK_UP) { velX = 0; velY = -1; } if(c == KeyEvent.VK_RIGHT) { velX = 1; velY = 0; } if(c == KeyEvent.VK_DOWN) { velX = 0; velY = 1; } } public void keyTyped(KeyEvent e){} public void keyReleased(KeyEvent e) { velX = 0; velY = 0; } public static void main(String[] args) { Test t = new Test(); JFrame jf = new JFrame(); jf.setTitle("Tutorial"); jf.setSize(700, 600); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); jf.add(t); jf.setVisible(true); } 

我的问题是我只要用户在键盘上按住右箭头就会改变图像，当用户放开它时，它会返回默认图像。 请告诉我该怎么做。 我认为这是Graphics类中的一系列if语句，然后将它们调用到键输入，但我不太确定。 我也在使用Eclipse。 谢谢。

Answer 1

1. 覆盖paintComponent而不是paint 。 有关详细信息，请参阅在AWT和Swing中 执行自定义绘画和绘画
2. 使用键绑定API而不是KeyListener ，它会减少问题。 有关更多详细信息，请参见如何使用键绑定

从本质上讲，您可以将Image作为类实例字段，由paintComponent方法绘制。 按下该键后，您可以将图像更改为“移动图像”，当它被释放时，将其更改回“默认图像”

更新了示例

 import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyEvent; import java.awt.image.BufferedImage; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.AbstractAction; import javax.swing.Action; import javax.swing.ActionMap; import javax.swing.InputMap; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.KeyStroke; import javax.swing.Timer; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class Test { public static void main(String[] args) { new Test(); } public Test() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } JFrame frame = new JFrame("Testing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(new TestPane()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public interface Mover { public enum Direction { LEFT, RIGHT, NONE; } public void setDirection(Direction direction); public Direction getDirection(); } public class TestPane extends JPanel implements Mover { private BufferedImage left; private BufferedImage right; private BufferedImage stand; private BufferedImage current; private Direction direction = Direction.NONE; private int xPos; private int yPos; public TestPane() { try { left = ImageIO.read(getClass().getResource("/Left.png")); right = ImageIO.read(getClass().getResource("/Right.png")); stand = ImageIO.read(getClass().getResource("/Stand.png")); current = stand; xPos = 100 - (current.getWidth() / 2); yPos = 100 - (current.getHeight() / 2); } catch (IOException exp) { exp.printStackTrace(); } bindKeyStrokeTo(WHEN_IN_FOCUSED_WINDOW, "move.left", KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), new MoveAction(this, Direction.LEFT)); bindKeyStrokeTo(WHEN_IN_FOCUSED_WINDOW, "stop.left", KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, true), new MoveAction(this, Direction.NONE)); bindKeyStrokeTo(WHEN_IN_FOCUSED_WINDOW, "move.right", KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), new MoveAction(this, Direction.RIGHT)); bindKeyStrokeTo(WHEN_IN_FOCUSED_WINDOW, "stop.right", KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), new MoveAction(this, Direction.NONE)); Timer timer = new Timer(40, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { updatePosition(); repaint(); } }); timer.start(); } protected void bindKeyStrokeTo(int condition, String name, KeyStroke keyStroke, Action action) { InputMap im = getInputMap(condition); ActionMap am = getActionMap(); im.put(keyStroke, name); am.put(name, action); } @Override public Direction getDirection() { return direction; } @Override public void setDirection(Direction direction) { this.direction = direction; } protected void updatePosition() { switch (getDirection()) { case LEFT: current = left; xPos -= 1; break; case RIGHT: current = right; xPos += 1; break; case NONE: current = stand; break; } if (xPos < 0) { xPos = 0; current = stand; } else if (xPos + current.getWidth() > getWidth()) { current = stand; xPos = getWidth() - current.getWidth(); } } @Override public Dimension getPreferredSize() { return new Dimension(200, 200); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); g2d.drawImage(current, xPos, yPos, this); g2d.dispose(); } } public class MoveAction extends AbstractAction { private Mover mover; private Mover.Direction direction; public MoveAction(Mover mover, Mover.Direction direction) { this.mover = mover; this.direction = direction; } @Override public void actionPerformed(ActionEvent e) { mover.setDirection(direction); } } }