spring-security/docs/modules/ROOT/pages/servlet/integrations/localization.adoc

[[localization]]
= Localization
Spring Security supports localization of exception messages that end users are likely to see.
If your application is designed for English-speaking users, you need not do anything as, by default, all Security messages are in English.
If you need to support other locales, this section contains everything you need to know.

All exception messages, including messages related to authentication failures and access being denied (authorization failures), can be localized.
Exceptions and logging messages that are focused on developers or system deployers (including incorrect attributes, interface contract violations, using incorrect constructors, startup time validation, debug-level logging) are not localized and instead are hard-coded in English within Spring Security's code.

In the `spring-security-core-xx.jar`, you find an `org.springframework.security` package that, in turn, contains a `messages.properties` file as well as localized versions for some common languages.
Your `ApplicationContext` should refer to this, as Spring Security classes implement Spring's `MessageSourceAware` interface and expect the message resolver to be dependency injected at application context startup time.
Usually, all you need to do is register a bean inside your application context to refer to the messages.
The following listing shows an example:

====
[source,xml]
----
<bean id="messageSource"
	class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="classpath:org/springframework/security/messages"/>
</bean>
----
====

The `messages.properties` is named in accordance with standard resource bundles and represents the default language supported by Spring Security messages.
This default file is in English.

To customize the `messages.properties` file or support other languages, you should copy the file, rename it accordingly, and register it inside the preceding bean definition.
There are not a large number of message keys inside this file, so localization should not be considered a major initiative.
If you do perform localization of this file, consider sharing your work with the community by logging a JIRA task and attaching your appropriately-named localized version of `messages.properties`.

Spring Security relies on Spring's localization support in order to actually look up the appropriate message.
For this to work, you have to make sure that the locale from the incoming request is stored in Spring's `org.springframework.context.i18n.LocaleContextHolder`.
Spring MVC's `DispatcherServlet` does this for your application automatically. However, since Spring Security's filters are invoked before this, the `LocaleContextHolder` needs to be set up to contain the correct `Locale` before the filters are called.
You can either do this in a filter yourself (which must come before the Spring Security filters in `web.xml`) or you can use Spring's `RequestContextFilter`.
See the Spring Framework documentation for further details on using localization with Spring.

The `contacts` sample application is set up to use localized messages.