java 34 lines · 6 steps

Localized bean validation messages in Spring

Wire a custom MessageSource into Spring's validator so constraint messages are resolved from properties files per locale.

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Spring Intermediate internationalization bean-validation configuration message-source locale
1@Configuration
2public class ValidationConfig implements WebMvcConfigurer {
3 
4 @Bean
5 public MessageSource messageSource() {
6 ReloadableResourceBundleMessageSource source = new ReloadableResourceBundleMessageSource();
7 source.setBasenames("classpath:messages/validation", "classpath:messages/labels");
8 source.setDefaultEncoding(StandardCharsets.UTF_8.name());
9 source.setFallbackToSystemLocale(false);
10 source.setUseCodeAsDefaultMessage(false);
11 source.setCacheSeconds(30);
12 return source;
13 }
14 
15 @Bean
16 public LocalValidatorFactoryBean localValidatorFactoryBean(MessageSource messageSource) {
17 LocalValidatorFactoryBean factory = new LocalValidatorFactoryBean();
18 factory.setValidationMessageSource(messageSource);
19 return factory;
20 }
21 
22 @Bean
23 public LocaleResolver localeResolver() {
24 AcceptHeaderLocaleResolver resolver = new AcceptHeaderLocaleResolver();
25 resolver.setDefaultLocale(Locale.ENGLISH);
26 resolver.setSupportedLocales(List.of(Locale.ENGLISH, Locale.forLanguageTag("pt-BR"), Locale.GERMAN));
27 return resolver;
28 }
29 
30 @Override
31 public Validator getValidator() {
32 return localValidatorFactoryBean(messageSource());
33 }
34}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Feeding a MessageSource into the validator lets constraint messages come from your own properties files instead of hardcoded defaults.
  2. 2AcceptHeaderLocaleResolver picks the response locale from the request's Accept-Language header against a supported set.
  3. 3Turning off system-locale fallback and code-as-default forces missing keys to surface loudly during development.

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