Internationalization Spring Boot

Run application and go to the browser:

• http://localhost:8080 - demo for change lang
• http://localhost:8080/local - show current local code

FAQ

Where store my messages?

With Spring Boot, we can use the messages.properties (/src/main/resources/messages.properties) file which will be used for the default locale, US in our case.

For other language we must add local code, for example for French: messages_fr.properties

How change default lang to other?

1. By application.properties to French:

spring.mvc.locale=fr
spring.mvc.locale-resolver=fixed

see application.properties

2. By bean configuration:

@Configuration
public class AppConfig implements WebMvcConfigurer {
    @Bean
    public LocaleResolver localeResolver() {
        SessionLocaleResolver sessionLocaleResolver = new SessionLocaleResolver();
        sessionLocaleResolver.setDefaultLocale(Locale.US);
        return sessionLocaleResolver;
    }
}

see AppConfig.java

How switch lang?

Use LocaleChangeInterceptor

@Configuration
public class AppConfig implements WebMvcConfigurer {

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

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

And then when we will pass the GET parameter: ?lang=fr language will be changed to transmitted

How get message from message_code?

Use MessageSource method getMessage

@RequestMapping("/trulala")
public String trulala(Locale locale) {
    return messageSource.getMessage("trulala", null, locale);
}