News

2007-07-03: Going fast with these minor versions, 0.0.7 is available. Since the 0.0.4 release, a typo with the noscript has been fixed and the themed output has also been fixed. Thanks to Darko Jankovic for pointing these errors out. Also, a convenience method has been added instead of using the options to createRecaptchaHtml(errorMessage, theme, tabindex). Finally, the output has been adjusted to validate as XHTML, thanks to Carl Hagenmaier for pointing that out.

2007-06-28: There is now a version 0.0.4 availble. This time some smaller fixes to make it work under JDK 1.4. Thanks to Maelcum for pointing this out.

Getting

You can get the source for the recaptcha4j library by subversion checkout. Just follow the links in the left menu, under the SCM point.

Another option is to download a prebuilt jar file. That can be done from here.

Finally, if you're using Maven2, you can include it as dependency in your project simply by adding http://tanesha.net/maven2 in your POM like this:

<project>
    ...
        <dependency>
                <groupId>net.tanesha.recaptcha4j</groupId>
                <artifactId>recaptcha4j</artifactId>
                <version>${version}</version>
        </dependency>
    ...
    
    <repositories>
        ...
        <repository>
                        <id>taneshanet</id>
                        <url>http://tanesha.net/maven2</url>
                </repository>
        ...
    </repositories>
</project>

Using

Before you can use the library, you need to get API keys from their website. Follow the link above to find those. After that you have to call the library from your code. You can do that something like this (example in JSP):

        ...
<%
        // create recaptcha without <noscript> tags
        ReCaptcha captcha = ReCaptchaFactory.newReCaptcha("my-public-key", "my-private-key", false);
        String captchaScript = captcha.createRecaptchaHtml(request.getParameter("error"), null);
        
        out.print(captchaScript);
%>
        ...

Checking the captcha goes like this:

        ...
<%
        // create recaptcha without <noscript> tags
        ReCaptcha captcha = ReCaptchaFactory.newReCaptcha("my-public-key", "my-private-key", false);
        ReCaptchaResponse response = captcha.checkAnswer(request.getRemoteAddr(), request.getParameter("recaptcha_challenge_field"), request.getParameter("recaptcha_response_field"));

        if (response.isValid()) {
                out.print("Success");
        }
        else {
                out.print(response.getErrorMessage());
        }
%>
        ...

There is a small example web-app in the SVN-repository which you can find here: https://svn.tanesha.net/svn/sandbox/recaptcha4j-example/trunk/.

Using with Spring

If you are using the Spring framework then you can configure the ReCaptcha as a bean in Spring quite easily, so you can use it for injecting into whatever other logic you might have. Instead of using the ReCaptchaFactory indirection, you should use the ReCaptchaImpl directly and then use the ReCaptcha interface in your depending beans.

<beans>
        ...
        <bean id="reCaptcha" class="net.tanesha.recaptcha4j.ReCaptchaImpl">
                <property name="privateKey" value="my private key" />
                <property name="publicKey" value="my public key" />
                <property name="recaptchaServer" value="http://api.recaptcha.net" />
                <!-- Or, if you want to use SSL, then use this:
                        <property name="recaptchaServer" value="http://secure-api.recaptcha.net" />
                -->
                <property name="includeNoscript" value="false" />
        </bean>
        ...
</beans>

Problems and solutions

• Java is little eager to cache, so you must set the System property networkaddress.cache.ttl. You can do that by passing -Dnetworkaddress.cache.ttl=500 to your app-server, or by adding System.setProperty("networkaddress.cache.ttl", "500"); somewhere in your code. See java.sun.com for more information.