private static void outputVerifyCode(HttpServletRequest request,

            HttpServletResponse response) throws Exception {

        BufferedImage img = new BufferedImage(68, 22, 1);

        Graphics g = img.getGraphics();

        Random r = new Random();

        Color c = new Color(200, 150, 255);

        g.setColor(c);

        g.fillRect(0, 0, 68, 22);

        StringBuffer sb = new StringBuffer();

        char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();

        int len = ch.length;

        for (int i = 0; i < 4; i++) {

            int index = r.nextInt(len);

            g.setColor(new Color(r.nextInt(88), r.nextInt(188), r.nextInt(255)));

            g.setFont(new Font("Arial", 2, 22));

            g.drawString(String.valueOf(ch[index]), i * 15 + 3, 18);

            sb.append(ch[index]);

        }

        request.getSession().setAttribute("verifypic", sb);

        ImageIO.write(img, "JPG", response.getOutputStream());

    }

private boolean chekcVerifycode(String inputStr, String correctStr) {

        return inputStr.toLowerCase().equals(correctStr.toLowerCase());

    }