我如何在java中使用KeyListener？
如何在此代码上使用KeyListener进行上下移动？ 我知道如何使用KeyListener，但我不知道它在这个代码上的位置。
import java.awt.*; import java.awt.image.*; import java.awt.event.*; import java.awt.geom.*; import javax.swing.*; public class ControlPanel extends JPanel implements Runnable,ActionListener,KeyListener,MouseListener{ private MainPanel main; private final static int maxWidth = 800, maxHeight = 600; //width & height of JPanel private boolean running; //keeps track of state of the program private Thread thread; private Graphics2D graphics; private Image image; //used for double buffering private BufferedImage bgImage; private String s = ""; Font f = new Font("Times New Roman",Font.PLAIN,50); Timer t = new Timer(2000,this); private int typed = 0; private int x = 50,y = 500; public ControlPanel(MainPanel main) { this.setDoubleBuffered(false); //we'll use our own double buffering method this.setBackground(Color.black); this.setPreferredSize(new Dimension(maxWidth, maxHeight)); this.setFocusable(true); this.requestFocus(); this.main = main; addKeyListener(this); addMouseListener(this); t.start(); } public static void main(String[] args) { new MainPanel(); } public void addNotify() { super.addNotify(); startGame(); } public void stopGame() { running = false; } //Creates a thread and starts it public void startGame() { if (thread == null || !running) { thread = new Thread(this); } thread.start(); //calls run() } public void run() { running = true; init(); while (running) { createImage(); //creates image for double buffering ///////////////USE THESE 2 METHODS//////////////////// update(); //use this to change coordinates, update values, etc draw(); //use this to draw to the screen ////////////////////////////////////////////////////// drawImage(); //draws on the JPanel } System.exit(0); } //Use this to create or initialize any variables or objects you have public void init() { } public void initGame(){ } //Use this to update anything you need to update public void update() { } //Use this to draw anything you need to draw public void draw() { graphics.setColor(Color.WHITE); graphics.fillRect(250, 450, 300,100); graphics.setColor(Color.WHITE); graphics.fillRect(250, 320, 300,100); graphics.setColor(Color.GREEN); graphics.setFont(f); graphics.drawString(s, x, y); typed = 0; graphics.setFont(f); graphics.setColor(Color.blue); graphics.drawString("HANGMAN", 270,75); graphics.setFont(f); graphics.setColor(Color.blue); graphics.drawString("PLAY", 330, 390); graphics.setFont(f); graphics.setColor(Color.blue); graphics.drawString("QUIT", 330, 520); graphics.setColor(Color.red); graphics.drawRect(248, 318, 304,104); } //creates an image for double buffering public void createImage() { if (image == null) { image = createImage(maxWidth, maxHeight); if (image == null) { System.out.println("Cannot create buffer"); return; } else graphics = (Graphics2D)image.getGraphics(); //get graphics object from Image } if (bgImage == null) { graphics.setColor(Color.black); graphics.fillRect(0, 0, maxWidth, maxHeight); //System.out.println("No background image"); } else { //draws a background image on the Image graphics.drawImage(bgImage, 0, 0, null); } } //outputs everything to the JPanel public void drawImage() { Graphics g; try { g = this.getGraphics(); //a new image is created for each frame, this gets the graphics for that image so we can draw on it if (g != null && image != null) { g.drawImage(image, 0, 0, null); g.dispose(); //not associated with swing, so we have to free memory ourselves (not done by the JVM) } image = null; }catch(Exception e) {System.out.println("Graphics objects error");} } public void actionPerformed(ActionEvent e) { // TODO Auto-generated method stub } public void keyPressed(KeyEvent e) { } public void keyReleased(KeyEvent e) { } public void keyTyped(KeyEvent e) { typed = 1; s+=Character.toString(e.getKeyChar()); s+=" "; System.out.println(s); } @Override public void mouseClicked(MouseEvent e) { System.out.println(e.getPoint()); } @Override public void mouseEntered(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mousePressed(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } } KeyListener未指定用于侦听Swing JComponents的键盘事件，而是使用KeyBindings ，输出到Swing GUI应该来自Swing Action
您已通过调用此方法添加了关键侦听器
addKeyListener(this);