Implementing Captcha in GWT-Ext 2.0.3

Hello All,

I am using GWT-Ext 2.0.3. I have implemented SimpleCaptcha in my project.I am not able to refresh the captcha image when I reload the panel.I am using simplecaptcha-1.2.1.jar file to implemet captcha.

I have created a servlet to display captcha image.

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import nl.captcha.Captcha;
import nl.captcha.backgrounds.GradiatedBackgroundProducer;
import nl.captcha.servlet.CaptchaServletUtil;
import nl.captcha.servlet.SimpleCaptchaServlet;

public class ExtendedCaptchaServlet  extends SimpleC开发者_高级运维aptchaServlet  {

    private static final long serialVersionUID = -3280477565969758716L;

    //@Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp)

    throws ServletException, IOException {

        HttpSession session = req.getSession();

        Captcha captcha = new Captcha.Builder(200, 50)

        .addText()

        .addBackground(new GradiatedBackgroundProducer()).addNoise()

        .addBorder()

        .build();

        session.setAttribute("captcha", captcha);
        CaptchaServletUtil.writeImage(resp, captcha.getImage());

    }
}

Entry in web.xml

<servlet>
    <servlet-name>SimpleCaptcha</servlet-name>
    <servlet-class> com.server.test.ExtendedCaptchaServlet 
    </servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>SimpleCaptcha</servlet-name>
    <url-pattern>/SimpleCaptcha.jpg</url-pattern>
</servlet-mapping>

My GWT Panel

FormPanel formPanel = new FormPanel();
Image captchaImage = new Image("/SimpleCaptcha.jpg");
formPanel.add(captchaImage);

It is displays the new captcha image each time when I refresh the page from browser. But it does not display the image when I reload the form panel.

Can anyone help me?

---

try to add "timestamp"

Image captchaImage = new Image("/SimpleCaptcha.jpg?" + Math.floor(Math.random()*100));