Question

Can I use recaptcha with apache wicket 1.5.3? Is there some good example?

Answer 1

Have you read this?

I have added the guide here in case page disappears.

Usage

We will create a panel called RecaptchaPanel. In order to use this component to your application all you’ll have to do is this:

add(new RecaptchaPanel("recaptcha"));

and of course, add the component in your markup:

<div wicket:id="recaptcha"></div>

Implementation

Implementation is simple. All you have to do, is to follow several steps:

Add recaptcha dependency to your project

<dependency>
 <groupid>net.tanesha.recaptcha4j</groupid>
 <artifactid>recaptcha4j</artifactid>
 <version>0.0.7</version>
</dependency>

This library hides the implementation details and expose an API for dealing with recaptcha service.

Create associated markup (RecaptchaPanel.html)

<wicket:panel><div wicket:id="captcha"></div></wicket:panel>

Create RecaptchaPanel.java

import net.tanesha.recaptcha.ReCaptcha;
import net.tanesha.recaptcha.ReCaptchaFactory;
import net.tanesha.recaptcha.ReCaptchaImpl;
import net.tanesha.recaptcha.ReCaptchaResponse;

/**
 * Displays recaptcha widget. It is configured using a pair of public/private keys which can be registered at the
 * following location:
 * 
* https://www.google.com/recaptcha/admin/create
 * <br>
 * More details about recaptcha API: http://code.google.com/apis/recaptcha/intro.html
 *
 * @author Alex Objelean
 */
@SuppressWarnings("serial")
public class RecaptchaPanel extends Panel {
  private static final Logger LOG = LoggerFactory.getLogger(RecaptchaPanel.class);
  @SpringBean
  private ServiceProvider serviceProvider;


  public RecaptchaPanel(final String id) {
    super(id);
    final ReCaptcha recaptcha = ReCaptchaFactory.newReCaptcha(serviceProvider.getSettings().getRecaptchaPublicKey(),
      serviceProvider.getSettings().getRecaptchaPrivateKey(), false);
    add(new FormComponent<void>("captcha") {
      @Override
      protected void onComponentTagBody(final MarkupStream markupStream, final ComponentTag openTag) {
        replaceComponentTagBody(markupStream, openTag, recaptcha.createRecaptchaHtml(null, null));
      }

      @Override
      public void validate() {
        final WebRequest request = (WebRequest)RequestCycle.get().getRequest();

        final String remoteAddr = request.getHttpServletRequest().getRemoteAddr();
        final ReCaptchaImpl reCaptcha = new ReCaptchaImpl();
        reCaptcha.setPrivateKey(serviceProvider.getSettings().getRecaptchaPrivateKey());

        final String challenge = request.getParameter("recaptcha_challenge_field");
        final String uresponse = request.getParameter("recaptcha_response_field");
        final ReCaptchaResponse reCaptchaResponse = reCaptcha.checkAnswer(remoteAddr, challenge, uresponse);

        if (!reCaptchaResponse.isValid()) {
          LOG.debug("wrong captcha");
          error("Invalid captcha!");
        }
      }
    });
  }
}
</void>

Things to notice:

• ServiceProvider – is a spring bean containing reCaptcha configurations (public key and private key). These keys are different depending on the domain where your application is deployed (by default works for any key when using localhost domain). You can generate keys here: https://www.google.com/recaptcha/admin/create
• The RecaptchaPanel contains a FormComponent, which allows implementing validate method, containing the validation logic.
• Because reCaptcha use hardcoded values for hidden fields, this component cannot have multiple independent instances on the same page.