Question

paintComponent画的图怎么使用KeyListener使它动起来？

Answer 1

import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

/**
* 简单例子，按下哪个键，就会显示什么内容，不可显字符就算了，不多解释了
*/
public class Sanke extends JFrame implements KeyListener {
public MyComponent my = new MyComponent();

public Sanke() {
this.setSize(100, 100);

this.add(my);
this.addKeyListener(this);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}

@Override
public void keyTyped(KeyEvent e) {
}

@Override
public void keyPressed(KeyEvent e) {
char c = e.getKeyChar();
my.update(c);
}

@Override
public void keyReleased(KeyEvent e) {
}

public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new Sanke();
}
});
}
}

class MyComponent extends JComponent {
char c = 'a';
Font font = new Font("宋体", Font.BOLD, 30);

public void update(char c) {
this.c = c;
this.repaint();
}

@Override
public void paint(Graphics g) {
super.paint(g);
g.setFont(this.font);
g.drawString(String.valueOf(c), 20, 50);
}
}