Apache Struts 2 Documentation > Home > Guides > Core Developers Guide > Localization
Added by cv_, last edited by Ted Husted on Aug 12, 2007  (view change)

Overview

The framework supports internationalization (i18n) in the following places:

  1. the UI Tags
  2. Messages and Errors from the ValidationAware interface (implemented by ActionSupport and ValidationAwareSupport)
  3. Within action classes that extend ActionSupport through the getText() method

Resource Bundle Search Order

Resource bundles are searched in the following order:

  1. ActionClass.properties
  2. BaseClass.properties (all the way to Object.properties)
  3. Interface.properties (every interface and sub-interface)
  4. ModelDriven's model (if implements ModelDriven), for the model object repeat from 1
  5. package.properties (of the directory where class is located and every parent directory all the way to the root directory)
  6. search up the i18n message key hierarchy itself
  7. global resource properties

For more, see the LocalizedTextUtil class.

Package hierarchy

To clarify #5, while traversing the package hierarchy, Struts 2 will look for a file package.properties:

com/
  acme/
    package.properties
    actions/
      package.properties
      FooAction.java
      FooAction.properties

If FooAction.properties does not exist, com/acme/action/package.properties will be searched for, if not found com/acme/package.properties, if not found com/package.properties, etc.

Examples

There are several ways to access the message resources, including getText, the text tag, and the i18n tag.

Using getText from a Tag

To display i18n text, use a call to getText in the property tag, or any other tag, such as the UI tags. (The getText technique is especially useful for labels of UI tags.)

<s:property value="getText('some.key')" />

Using the text tag

The text tag retrieves a message from the default resource bundle.

<-- Fourth Example -->
<s:text name="some.key" />

<-- Fifth Example -->
<s:text name="some.invalid.key" >
   The Default Message That Will Be Displayed
</s:text>

Using the I18n tag

The i18n tag pushes an arbitrary resource bundle on to the value stack. Other tags within the scope of the i18n tag can display messages from that resource bundle.

<s:i18n name="some.package.bundle" >
     <s:text name="some.key" />
</s:i18n>

Internationalizing SiteMesh decorators is possible, but there are quirks. See SiteMesh Plugin for more.

Using the Key attribute of UI Tags

The key attribute of most UI tags can be used to retrieve a message from a resource bundle:

<s:textfield key="some.key" name="textfieldName"/>

I18n Interceptor

Essentially, the i18n Interceptor pushes a locale into the ActionContext map upon every request. The framework components that support localization all utilize the ActionContext locale. See I18n Interceptor for details.

Global Resources (struts.custom.i18n.resources) in struts.properties

A global resource bundle could be specified programatically, as well as the locale.

Comparison with Struts 1

Struts 1 users should be familiar with the application.properties resource bundle, where you can put all the messages in the application that are going to be translated. Struts 2, though, splits the resource bundles per action or model class, and you may end up with duplicated messages in those resource bundles. A quick fix for that is to create a file called ActionSupport.properties in com/opensymphony/xwork2 and put it on your classpath. This will only work well if all your actions subclass XWork2's ActionSupport.

Resources

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