import java.applet.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class KeyEventFrame extends JApplet implements KeyListener{
StringBuffer sb;//创建一个字符缓冲区，用于存放键盘的输入
char ch;
JLabel info;//在键盘上添加一个标签，用于显示用户的输入
int x=0;
public void init(){
info=new JLabel();
info.setBackground(Color.blue);
info.setSize(100,100);
add(info);
setSize(400,300);
addKeyListener(this);//添加键盘监听事件
}
public void paint(Graphics g){
if(x==1)
g.drawOval(30, 20, 100, 100);//画圈
if(x==2)
g.drawLine(30, 20, 30,100);//画线
}
public void keyTyped(KeyEvent e){
char ch =e.getKeyChar();
if(ch=='c'||ch=='c'){
x=1;
info.setText("画圈");
repaint();
}
else if(ch=='1'||ch=='L'){
x=2;
info.setText("画线");
repaint();
}
else{
ch=e.getKeyChar();
sb=new StringBuffer();
sb.append(ch);
info.setText("请输入的是："+sb.toString());
}
}
public void keyPressed(KeyEvent e){
}
public void keyReleased(KeyEvent e){
}
}