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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.
Cookie Resolver
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
:
Property | Default | Description |
---|---|---|
|
class name + LOCALE |
The name of the cookie |
|
Servlet container default |
The maximum time a cookie persists on the client. If |
|
/ |
Limits the visibility of the cookie to a certain part of your site. When |
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>