- 使用摆动计时器进行实际运动。
- 按键启动计时器
- 释放密钥时将其停止。
- 更好的是，让计时器始终运行，但只能根据地图的状态移动精灵，地图的状态包含Direction枚举键和布尔值。
- 最好使用键绑定而不是KeyListeners。
例如，
import java.awt.*;import javax.swing.*;//!! import squarequest.sprites.*;import java.awt.event.*;import java.util.EnumMap;import java.util.HashMap;import java.util.Map;public class GamePanel extends JPanel { private static final int ANIMATION_DELAY = 15; private final int HEIGHT = 400; private final int WIDTH = 600; private Square square; private EnumMap<Direction, Boolean> dirMap = new EnumMap<>(Direction.class); private Map<Integer, Direction> keyToDir = new HashMap<>(); // !! private Circle circle; private Timer animationTimer; public GamePanel() { for (Direction dir : Direction.values()) { dirMap.put(dir, Boolean.FALSE); } keyToDir.put(KeyEvent.VK_UP, Direction.UP); keyToDir.put(KeyEvent.VK_DOWN, Direction.DOWN); keyToDir.put(KeyEvent.VK_LEFT, Direction.LEFT); keyToDir.put(KeyEvent.VK_RIGHT, Direction.RIGHT); // !! addKeyListener(new DirectionListener()); setKeyBindings(); setBackground(Color.white); setPreferredSize(new Dimension(WIDTH, HEIGHT)); setFocusable(true); square = new Square(); animationTimer = new Timer(ANIMATION_DELAY, new AnimationListener()); animationTimer.start(); } private void setKeyBindings() { int condition = WHEN_IN_FOCUSED_WINDOW; final InputMap inputMap = getInputMap(condition); final ActionMap actionMap = getActionMap(); boolean[] keyPressed = { true, false }; for (Integer keyCode : keyToDir.keySet()) { Direction dir = keyToDir.get(keyCode); for (boolean onKeyPress : keyPressed) { boolean onKeyRelease = !onKeyPress; // to make it clear how bindings work KeyStroke keyStroke = KeyStroke.getKeyStroke(keyCode, 0, onKeyRelease); Object key = keyStroke.toString(); inputMap.put(keyStroke, key); actionMap.put(key, new KeyBindingsAction(dir, onKeyPress)); } } } public void paintComponent(Graphics g) { super.paintComponent(g); square.display(g); } // public class DirectionListener implements KeyListener { // @Override // public void keyReleased(KeyEvent event) { // int keyCode = event.getKeyCode(); // if (keyToDir.keySet().contains(keyCode)) { // Direction dir = keyToDir.get(keyCode); // dirMap.put(dir, false); // } // } // // @Override // public void keyTyped(KeyEvent event) { // } // // @Override // public void keyPressed(KeyEvent event) { // int keyCode = event.getKeyCode(); // if (keyToDir.keySet().contains(keyCode)) { // Direction dir = keyToDir.get(keyCode); // dirMap.put(dir, true); // } // } // } private class AnimationListener implements ActionListener { @Override public void actionPerformed(ActionEvent evt) { boolean repaint = false; for (Direction dir : Direction.values()) { if (dirMap.get(dir)) { square.move(dir); repaint = true; } } if (repaint) { repaint(); } } } private class KeyBindingsAction extends AbstractAction { private Direction dir; boolean pressed; public KeyBindingsAction(Direction dir, boolean pressed) { this.dir = dir; this.pressed = pressed; } @Override public void actionPerformed(ActionEvent evt) { dirMap.put(dir, pressed); } } private static void createAndShowGUI() { GamePanel gamePanel = new GamePanel(); Jframe frame = new Jframe("GamePanel"); frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); frame.getContentPane().add(gamePanel); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); gamePanel.requestFocusInWindow(); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); }}enum Direction { UP(0, -1), DOWN(0, 1), LEFt(-1, 0), RIGHt(1, 0); private int incrX; private int incrY; private Direction(int incrX, int incrY) { this.incrX = incrX; this.incrY = incrY; } public int getIncrX() { return incrX; } public int getIncrY() { return incrY; }}class Square { private int x = 0; private int y = 0; private int w = 20; private int h = w; private int step = 1; private Color color = Color.red; private Color fillColor = new Color(255, 150, 150); private Stroke stroke = new BasicStroke(3f, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND); public void display(Graphics g) { Graphics2D g2d = (Graphics2D) g.create(); g2d.setColor(fillColor); g2d.fillRect(x, y, w, h); g2d.setStroke(stroke); g2d.setColor(color); g2d.drawRect(x, y, w, h); g2d.dispose(); } public void setStep(int step) { this.step = step; } public void move(Direction dir) { x += step * dir.getIncrX(); y += step * dir.getIncrY(); }// public void moveRight() {// x++;// }//// public void moveLeft() {// x--;// }//// public void moveUp() {// y--;// }//// public void moveDown() {// y++;// }}
