ClassLoader portalClassLoader = PortalClassLoaderUtil.getClassLoader();
@SuppressWarnings("unchecked")
Class<Captcha> captchaClass = (Class<Captcha>) portalClassLoader.loadClass(captchaClassName);
CaptchaUtil captchaUtil = new CaptchaUtil();
Captcha captcha = captchaClass.newInstance();
captchaUtil.setCaptcha(captcha);
CaptchaUtil.serveImage(httpServletRequest, captchaHttpServletResponse);
String captchaText = (String) httpServletRequest.getSession().getAttribute(CAPTCHA_TEXT);
portletSession.setAttribute(CAPTCHA_TEXT, captchaText);