编写一个组合鼠标事件和键盘事件的程序，该程序模拟一个电子白板，用户用鼠标在白板上画画，并通过键盘在上面写字

//<applet code = MouseAndKeyDemo.class height = 100 width = 150>
//</applet>
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class MouseAndKeyDemo extends Applet{
protected int lastX = 0, lastY = 0;
public void init()
{
addMouseListener(new PositionRecorder());
addMouseMotionListener(new LineDrawer());
addKeyListener(new CharDrawer());
setForeground(Color.blue);
setBackground(Color.white);
}
protected void record(int x, int y)
{
lastX = x;
lastY = y;
}
private class PositionRecorder extends MouseAdapter
{
public void mouseEnter(MouseEvent e)
{
requestFocus();
record(e.getX(),e.getY());
}
public void mousePressed(MouseEvent e)
{
record(e.getX(),e.getY());
}
}
private class LineDrawer extends MouseMotionAdapter
{
public void mouseDragged(MouseEvent e)
{
int x = e.getX();
int y = e.getY();
Graphics g = getGraphics();
g.drawLine(lastX, lastY, x, y);
record(x, y);
}
}
private class CharDrawer extends KeyAdapter
{
public void keyTyped(KeyEvent event)
{
String s = String.valueOf(event.getKeyChar());
getGraphics().drawString(s, lastX, lastY);
record(lastX + 11, lastY);
}
}
}