Apache Struts 2 Google AppEngine plugin

Plugin supporting developing and running Apache Struts 2 based application on Google AppEngine.

Installation

Just add this plugin as a dependency in pom.xml:

<dependency>
  <groupId>com.gruuf</groupId>
  <artifactId>struts2-gae-plugin</artifactId>
  <version>[VERSION]</version>
</dependency>

File upload support

To provide a proper file upload support on the Google AppEngine you must use the below filter instead of the one provided by Struts, update web.xml as follow:

<filter>
  <filter-name>struts2</filter-name>
  <filter-class>com.gruuf.struts2.gae.dispatcher.GaePrepareAndExecuteFilter</filter-class>
</filter>

This filter detects if OGNL was properly configured, to do so add the following listener to web,xml

<listener>
  <listener-class>com.gruuf.struts2.gae.dispatcher.GaeInitListener</listener-class>
</listener>

It also redefine Dispatcher's getSaveDir to allow properly upload files on AppEngine.

Fields

Now define fields to keep information about the uploaded file, please be aware that there is an abstraction layer in the Apache Struts which uses a UploadedFile interface instead of the File class (there is a fallback to File but it won't work in GAE). This means you must define your file as follow:

private UploadedFile file;

// getter & setter

reCAPTCHA support

There is a dedicated interceptor with connected interface to allow perform reCAPTCHA validation per action.

First you must define your reCAPTCHA secret using a constant:

<constant name="struts.gae.reCaptchaSecret" value="${env.GRUUF_RECAPTCHA_SECRET}"/>

Now your action can implement ReCaptchaAware interface and implement the below methods:

• setReCaptchaResult - you will get true when reCAPTCHA validation has passed
• isReCaptchaEnabled - allows you enabling/disabling reCAPTCHA validation per action, e.g.: when user is logged-in you don't want to perform the validation

The last thing is to define the reCAPTCHA interceptor and add it to your interceptors stack:

<interceptor name="reCaptcha" class="com.gruuf.struts2.gae.recaptcha.ReCaptchaInterceptor"/>

<interceptor-stack name="reCaptchaStack">
    <interceptor-ref name="strutsDefault"/>
  <interceptor-ref name="reCaptcha"/>
</interceptor-stack>

And finally you can add the reCAPTCHA code to your page.

Testimonials

This plugin is based on a code developed here https://code.google.com/archive/p/struts2-gae/

More details can be found here https://squarepusher782.wordpress.com/2010/10/01/file-upload-on-google-app-engine-using-struts2-revisited/

I have also taken some inspiration from here https://github.com/triologygmbh/reCAPTCHA-V2-java