Spring Framework Web Application Tutorials 3 - Externalization Of Text Messages & i18n

We start by creating the MessageSource Bean.

 @Bean
 public MessageSource messageSource() {
  ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
  messageSource.setBasename("locale/messages");
  messageSource.setDefaultEncoding("UTF-8");
  return messageSource;
 }

Above, we've set the path to the property files as resources/locale/messages. Next we create the property files: one for each language and one for default:

messages.properties:

hello.header=Welcome!
hello.content=Click here to advance to the next page
greeting.header=Hello on a second page!
greeting.content=Click here to go back

messages_fr.properties

hello.header=Welcome!
hello.content=Click here to advance to the next page
greeting.header=Bonjour!
greeting.content=Click here to go back

Next we create the localeResolver Bean and set the default locale, the cookie file name and the cookie's maximum age:

 @Bean
 public LocaleResolver localeResolver() {
  CookieLocaleResolver resolver = new CookieLocaleResolver();
  resolver.setDefaultLocale(new Locale("fr"));
  resolver.setCookieName("myLocaleCookie");
  resolver.setCookieMaxAge(4800);
  return resolver;
 }

Lastly, we set up the way to update the locale through creating LocaleChangeInterceptor Bean and registering it as a interceptor through addInterceptors

 @Bean
 public LocaleChangeInterceptor localeChangeInterceptor() {
  LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
  localeChangeInterceptor.setParamName("mylocale");
  return localeChangeInterceptor;
 }

 @Override
 public void addInterceptors(InterceptorRegistry registry) {
  registry.addInterceptor(localeChangeInterceptor());
 }

In the test.html, we call the message through the Thymeleaf notation as below:

<h3>i18n</h3>
<p th:text="#{greeting.header}"></p>

The Result:

When we set the variable mylocale through the URL, the locale is updated and the messages_fr.properties file is used as a source: