Internationalizing Flex apps Pt 1

This is part 1 of a 3 part series on Internationalizng flex apps.

One of the many features available in Flex 2.0 is a ResourceBundle class, which allows for a standardized approach for internationalizing applications.  Many recent projects of mine have had requirements that we build applications so that they can easily be ported to other languages.  Traditionally, I’ve used a series of XML files for this, one for each of the various languages which need to be supported.  This strategy is still viable, and I still use it on some of my projects.  I’ve recently discovered a different approach, which is available natively in Flex.  Flex provides a ResourceBundle class, which allows you to set up your text in .properties files (identical structure that you would use for internationalizing java applications).  These properties files are arranged in a folder structure, relating to the language and country, so, the properties file for US English would be in a folder called en_US, the file for the UK would be en_UK, while the French would be in fr_FR.  The strucutre of the files is very simple, like this:

hello = Hello World
welcome = Welcome!

or, for the french version

hello = Bonjour Monde
welcome = Bienvenue

To use these in an application, you have two options:  you can use the @Resource command each time you need a value, or, you can declare a variable for the ResourceBundle, and use the getString(), getNumber(), getBoolean(), etc methods.  In this example, you can see both being used:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="vertical">
 <mx:Script>
  <![CDATA[
   import mx.resources.ResourceBundle;
   [ResourceBundle("helloWorld")]
   private static var rb:ResourceBundle;
   private function geti18nText(key:String):String{
    return rb.getString(key);
   }
  ]]>
 </mx:Script>
 <mx:Label fontSize="50" text="@Resource(key='hello', bundle='helloWorld')"/>
 <mx:Label fontSize="50" text="{geti18nText('welcome')}"/>
</mx:Application>

So, here you can see the top label uses the @Resource directive to specifically pull the hello key from the helloWorld bundle.  If the application is compiled for en_US, that key will show "Hello World," compile the same app for fr_FR, and it will read "Bonjour Monde"

The remaining trick is to tell the compiler which language to use, and where to find the files.    You can do this from the command line like this:

  mxmlc -locale en_UK -sp ../locales/{locale} -o HelloWorld_en_UK.swf I18N_HelloWorld.mxml
  mxmlc -locale fr_FR -sp ../locales/{locale} -o HelloWorld_fr_FR.swf I18N_HelloWorld.mxml

or, you can specifiy compiler arguments in flexbuilder

-locale en_US -sp ../locales/{locale}

I’ll put a zip of the files to use this up here over the weekend.

In my next article, I’ll explore how i often use xml files as an alternative to this…