Locale

Most parts of Spring’s architecture support internationalization, as the Spring web MVC framework does. DispatcherServlet lets you automatically resolve messages by using the client’s locale. This is done with LocaleResolver objects.

When a request comes in, the DispatcherServlet looks for a locale resolver and, if it finds one, it tries to use it to set the locale. By using the RequestContext.getLocale() method, you can always retrieve the locale that was resolved by the locale resolver.

In addition to automatic locale resolution, you can also attach an interceptor to the handler mapping (see Interception for more information on handler mapping interceptors) to change the locale under specific circumstances (for example, based on a parameter in the request).

Locale resolvers and interceptors are defined in the org.springframework.web.servlet.i18n package and are configured in your application context in the normal way. The following selection of locale resolvers is included in Spring.

Time Zone

In addition to obtaining the client’s locale, it is often useful to know its time zone. The LocaleContextResolver interface offers an extension to LocaleResolver that lets resolvers provide a richer LocaleContext, which may include time zone information.

When available, the user’s TimeZone can be obtained by using the RequestContext.getTimeZone() method. Time zone information is automatically used by any Date/Time Converter and Formatter objects that are registered with Spring’s ConversionService.

Header Resolver

This locale resolver inspects the accept-language header in the request that was sent by the client (for example, a web browser). Usually, this header field contains the locale of the client’s operating system. Note that this resolver does not support time zone information.

This locale resolver inspects a Cookie that might exist on the client to see if a Locale or TimeZone is specified. If so, it uses the specified details. By using the properties of this locale resolver, you can specify the name of the cookie as well as the maximum age. The following example defines a CookieLocaleResolver:

<bean id="localeResolver" class="org.springframework.web.servlet.i18n.CookieLocaleResolver">

	<property name="cookieName" value="clientlanguage"/>

	<!-- in seconds. If set to -1, the cookie is not persisted (deleted when browser shuts down) -->
	<property name="cookieMaxAge" value="100000"/>

</bean>

The following table describes the properties CookieLocaleResolver:

Session Resolver

The SessionLocaleResolver lets you retrieve Locale and TimeZone from the session that might be associated with the user’s request. In contrast to CookieLocaleResolver, this strategy stores locally chosen locale settings in the Servlet container’s HttpSession. As a consequence, those settings are temporary for each session and are, therefore, lost when each session ends.

Note that there is no direct relationship with external session management mechanisms, such as the Spring Session project. This SessionLocaleResolver evaluates and modifies the corresponding HttpSession attributes against the current HttpServletRequest.

Locale Interceptor

You can enable changing of locales by adding the LocaleChangeInterceptor to one of the HandlerMapping definitions. It detects a parameter in the request and changes the locale accordingly, calling the setLocale method on the LocaleResolver in the dispatcher’s application context. The next example shows that calls to all *.view resources that contain a parameter named siteLanguage now changes the locale. So, for example, a request for the URL, www.sf.net/home.view?siteLanguage=nl, changes the site language to Dutch. The following example shows how to intercept the locale:

<bean id="localeChangeInterceptor"
		class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor">
	<property name="paramName" value="siteLanguage"/>
</bean>

<bean id="localeResolver"
		class="org.springframework.web.servlet.i18n.CookieLocaleResolver"/>

<bean id="urlMapping"
		class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
	<property name="interceptors">
		<list>
			<ref bean="localeChangeInterceptor"/>
		</list>
	</property>
	<property name="mappings">
		<value>/**/*.view=someController</value>
	</property>
</bean>