//MouseEvents.java
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class MouseEvents extends Applet implements MouseListener
{
  String msg = "";
  int mouseX = 0, mouseY = 0;
  public void init() {
    addMouseListener(this);
  }
  public void mouseClicked(MouseEvent me)
  {
    mouseX = 0;
    mouseY = 10;
    msg = "鼠标被单击了";
    repaint();
  }
  public void mouseEntered(MouseEvent me)
  {
    mouseX = 0;
    mouseY = 10;
    msg = "鼠标进来了";
    repaint();
  }
  public void mouseExited(MouseEvent me)
  {
    mouseX = 0;
    mouseY = 10;
    msg = "鼠标被移走了";
    repaint();
  }
  public void mousePressed(MouseEvent me)
  {
    mouseX = me.getX();
    mouseY = me.getY();
    msg = "鼠标被按下了";
    repaint();
  }
  public void mouseReleased(MouseEvent me)
  {
    mouseX = me.getX();
    mouseY = me.getY();
    msg = "鼠标被放开了";
    repaint();
  }
  public void paint(Graphics g)
  {
    g.drawString(msg, mouseX, mouseY);
  }
  public static void main(String arg[])
  {
    MouseEvents A = new MouseEvents();
  }
}
请教一下repaint()是什么?

再多请教一下:讲解一下Applet类