help!!!!

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<%@ page import="java.awt.*" %>
<%@ page import="java.io.*" %>
<%@ page import="java.awt.image.*" %>
<%@ page import="java.awt.geom.*" %>
<%@ page import="com.sun.image.codec.jpeg.*" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head><body>
<br>观看旋转的椭圆
<form action="" method="post" name="form">
  <input type="submit" value="观看" name="Submit" >
</form>
<%
  String str=request.getParameter("submit");
  if(str!=null)
  {
    response.setContentType("image/jpeg");
int width=260, height=260;
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
g.setColor(Color.white);
g.fillRect(0, 0, width, height);
Graphics2D g_2d=(Graphics2D)g;
Ellipse2D ellipse=new Ellipse2D. Double (20,50,120,50);
g_2d.setColor(Color.blue);
AffineTransform trans=new AffineTransform();
  for(int i=1;i<=24;i++)
    {
  trans.rotate(15.0*Math.PI/180,75,75);
  g_2d.setTransform(trans);
  g_2d.draw(ellipse);
}
  g.dispose();
  OutputStream outClient= response.getOutputStream();
  JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(outClient);
  encoder.encode(image);
  }
  %>
</body>
</html>
  原封不动的抄的　为什么看不到旋转的椭圆