Internationalization Using Spring MVC

Spring MVC Internationalization

Interview Questions

Questions:-What is i18n (internationalization) and L10n (localization)?

Answer:- According to computer vocabulary, i18n means internationalization and L10n means localization. Here, in i18n -18 belongs to the number of letters between the first i and the last n in the word internationalization. Similarly, In L10n - 10 belongs to the number between the first L and last n in the word localization.
                                                            With the help of internationalization and localization, we can make software in different languages; even we can use it in our regional languages. A process through which software can adapt to various languages and regions without re- engineering is known as internationalization. Similarly, A process through which internationalized software can adapt a specific region or language by adding locale-specific components and translating text.
Spring MVC module, comes with few “LocaleResolver” which support s the internationalization or multiple languages features.

Spring Configuration
 

if we want to use Spring MVC module for supporting the internationalization, then in this case we have to register two beans.

Local Resolvers
 

it’s a component capable of resolving the locale and offer internationalized views which is used by a client. org.springframework.web.servlet.i18n is the package where Locale resolvers and interceptors are available and are configured in your application context in the normal way like other beans. All Known Implementing Classes are AbstractLocaleResolver, AcceptHeaderLocaleResolver,  CookieLocaleResolver, FixedLocaleResolver, SessionLocaleResolver

 SessionLocaleResolver

We have to register a “SessionLocaleResolver” bean. While registering this resolver the bean-id should be exactly the same as “localeResolver”, because it’s a predefined attribute from user’s session. For example:-

<bean id="localeResolver"

    class="org.springframework.web.servlet.i18n.SessionLocaleResolver">

    <property name="defaultLocale" value="en"/>

</bean>

AcceptHeaderLocaleResolver

Important Fact:

If we will not register any “localeResolver”, then the default AcceptHeaderLocaleResolver will be used, which resolves the locale by checking the accept-language header in the HTTP request. This header field contains the locale of the client's operating system. This is the default locale resolver and in order to use this locale resolver, we don't require configuring anything in spring configuration file.This locale resolver inspects the accept-language header in the request that was sent by the browser of the client.

CookieLocaleResolver

This locale resolver inspects a Cookie that might exist on the client, to see if a locale is specified. If so, it uses that specific locale. Using the properties of this locale resolver, you can specify the name of the cookie, as well as the maximum age. Find below an example of defining 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>

CookieLocaleResolver properties

Property	Default	Description
cookieName	classname + LOCALE	The name of the cookie
cookieMaxAge	Integer.MAX_INT	The maximum time a cookie will stay persistent on the client. If -1 is specified, the cookie will not be persisted. It will only be available until the client shuts down his or her browser.
cookiePath	/	Using this parameter, you can limit the visibility of the cookie to a certain part of your site. When cookiePath is specified, the cookie will only be visible to that path, and the paths below it.

  

LocaleChangeInterceptor

This Interceptor will allow for changing the current locale on every request, via a configurable request parameter. We have to register a “LocaleChangeInterceptor” and reference it to any handler mapping that need to supports the multiple languages. The “paramName” is the parameter value that’s used to set the locale. It calls setLocale() on the LocaleResolver that also exists in the context. All calls containing a parameter named siteLanguage will now change the locale. So a request for the following URL, http://localhost:7075/SpringMVCInternationalization/index.htm?siteLanguage=es will change the site language to Spanish.

Note: - siteLanguage is the value which we are passing against paramName attribute of LocaleChangeInterceptor.

Method Summary
boolean	preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)           This implementation always returns true.
void	setParamName(String paramName)           Set the name of the parameter that contains a locale specification in a locale change request.

In this case,

index.htm?siteLanguage=en – Get the message from English properties file.
index.htm?siteLanguage=es – Get the message from Spanish properties file.

<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.SessionLocaleResolver">

<property name="defaultLocale" value="en" />

</bean>

<bean id="urlMapping"

      class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">

    <property name="interceptors">

        <list>

            <ref bean="localeChangeInterceptor"/>

        </list>

    </property>

</bean>

<!-- Registering the bean -->

            <bean class="com.gaurav.spring.internationalization.controller.WelcomeController" />

            <!-- Registering the message properties files-->

            <bean id="messageSource"                  class="org.springframework.context.support.ReloadableResourceBundleMessageSource">

                         <property name="basenames">  

 <list>  

<value>/WEB-INF/resourcebundle/messages</value>  

</list>  

                        </property>                

<property name="defaultEncoding" value="UTF-8"/>

            </bean>

            <bean id="viewResolver"

            class="org.springframework.web.servlet.view.InternalResourceViewResolver" >

        <property name="prefix">

            <value>/WEB-INF/pages/</value>

        </property>

        <property name="suffix">

            <value>.jsp</value>

        </property>

    </bean>

welcome_en.properties

welcome.springmvcinternationalization = Welcome in England

welcome_es.properties

welcome. springmvcinternationalization = Welcome in Spain

We have to code Like below in the JSP page in order to use Internationalization.

<spring:message code=" welcome.springmvcinternationalization " text="default text"/>