HOW TO CREATE YOUR OWN CAPTCHA WITH JSF

1-Create a servlet

//This can be located at a package called servlets(next to entities and managed beans)
public class MyCaptcha extends HttpServlet{

      private int height = 0;

    private int width = 0;

    public static final String CAPTCHA_KEY = "captcha_key_name";

   @Override

    public void init(ServletConfig config) throws ServletException {

        super.init(config);

        height = Integer.parseInt(getServletConfig().getInitParameter("height"));

        width = Integer.parseInt(getServletConfig().getInitParameter("width"));

    }

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse response) throws IOException, ServletException {

        //Expire response

        response.setHeader("Cache-Control", "no-cache");

        response.setDateHeader("Expires", 0);

        response.setHeader("Pragma", "no-cache");

        response.setDateHeader("Max-Age", 0);

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        Graphics2D graphics2D = image.createGraphics();

        Hashtable<TextAttribute, Object> map = new Hashtable<TextAttribute, Object>();

        Random r = new Random();

        String token = Long.toString(Math.abs(r.nextLong()), 36);

        String ch = token.substring(0, 6);

        Color c = new Color(0.6662f, 0.4569f, 0.3232f);

       GradientPaint gp = new GradientPaint(30, 30, c, 15, 25, Color.white, true);

        graphics2D.setPaint(gp);

        Font font = new Font("Verdana", Font.CENTER_BASELINE, 26);

        graphics2D.setFont(font);

        graphics2D.drawString(ch, 2, 20);

        graphics2D.dispose();

        HttpSession session = req.getSession(true);

        session.setAttribute(CAPTCHA_KEY, ch);

        OutputStream outputStream = response.getOutputStream();

            ImageIO.write(image, "jpeg", outputStream);

        outputStream.close();

    }

}

2-Add the following settings to your web.xml:

<servlet>

            <servlet-name>Captcha</servlet-name>

            <servlet-class>servlets.MyCaptcha</servlet-class>

            <init-param>

                  <description>passing height</description>

                  <param-name>height</param-name>

                  <param-value>30</param-value>

            </init-param>

            <init-param>

                  <description>passing height</description>

                  <param-name>width</param-name>

                  <param-value>120</param-value>

            </init-param>

      </servlet>

      <servlet-mapping>

            <servlet-name>Captcha</servlet-name>

            <url-pattern>/Captcha.jpg</url-pattern>

      </servlet-mapping>

3- Add the captcha markup at the front page

<h:graphicImage id="capimg"

                                    value="#{facesContext.externalContext.requestContextPath}/../Captcha.jpg" />

                              <br />

                              <h:outputText value="*Napisite text koj vidite u slici " />

                              <h:inputText id="captchaSellerInput"

                                    value="#{registrationControllerSeller.captchaSellerInput}" />

4- Add the backing bean logic of the captha:

HttpServletRequest request = (HttpServletRequest) FacesContext

            .getCurrentInstance().getExternalContext().getRequest();

            Boolean isResponseCorrect = Boolean.FALSE;

            javax.servlet.http.HttpSession session = request.getSession();

            String parm = captchaSellerInput;

            String c = (String) session.getAttribute(MyCaptcha.CAPTCHA_KEY);

            if (parm.equals(c)) {
                 //CAPTCHA CORRECT INPUT
            }
            else {
                //CAPTCHA INCORRECT INPUT  

            }