Friday, June 10, 2011

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  
            }


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