response.setContentType("image/jpeg");
BufferedImage image = new BufferedImage(60,20,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
Random r = new Random();
g.setColor(new Color(r.nextInt(255),r.nextInt(255), r.nextInt(255)));
g.fillRect(0, 0, 60, 20);
g.setColor(new Color(0,0,0));
String number = String.valueOf( r.nextInt(99999));
HttpSession session = request.getSession();
session.setAttribute("number", number);
g.drawString(number, 5, 15);
g.setColor( new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)));
g.drawLine(r.nextInt(60),r.nextInt(20),r.nextInt(60), r.nextInt(20));
OutputStream os =response.getOutputStream();
JPEGImageEncoder encoder =JPEGCodec.createJPEGEncoder(os);
encoder.encode(image);