Spring boot configuration file (annotation-based) - configures localization

SpringMVCWebConfig.java

package mongodbdemo.config;

import java.util.Locale;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ReloadableResourceBundleMessageSource;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.i18n.CookieLocaleResolver;
import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;

/* Configuration for localization of Spring boot app
 * 
 * Place your resource files in src/main/resources/lang/
 * and name them 
 *   messages.properties (default fallback)
 *   messages_de.properties
 *   messages_en.properties
 *   
 * messages.properties example content:
 * welcome=Welcome
 * 
 * In Thymeleaf templates you can use this text as following:
 * <h1 th:text="#{welcome}">Welcome</h1>
 * 
 * Switching between locales like this in Thymeleaf template:
 * <p>Language : <a href="?language=en">English</a>|<a href="?language=de">German</a></p>
 * 
 */

@Configuration
@EnableWebMvc
@ComponentScan
public class MvcWebConfig  extends WebMvcConfigurerAdapter {

        static final Logger logger = LoggerFactory.getLogger(MvcWebConfig.class);

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

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

        @Bean(name = "localeResolver")
        public CookieLocaleResolver localeResolver() {
                CookieLocaleResolver localeResolver = new CookieLocaleResolver();
                Locale defaultLocale = new Locale("en");
                localeResolver.setDefaultLocale(defaultLocale);
                return localeResolver;
        }

        @Bean
        public ReloadableResourceBundleMessageSource messageSource() {
                ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
                messageSource.setBasename("classpath:lang/messages");
                messageSource.setCacheSeconds(10); //reload messages every 10 seconds
                return messageSource;
        }
        
// as alternative with-out automatic reloading, you could use the following:
//        @Bean
//        public ResourceBundleMessageSource messageSource() {
//                ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
//                messageSource.setBasename("lang/messages");
//                return messageSource;
//        }
}