How to make spring boot default to application/json;charset=utf-8 instead of application/json;charset=iso-8859-1 - spring

Question

I am updating spring-boot from 1.3.6 to 2.1.3 and while before responses had content type application/json;charset=UTF-8, now I am getting a charset of iso-8859-1.
I would like to have utf 8.
My controller looks like this:
#Controller
public class MyController {
#RequestMapping(value={"/myService/{serviceId}"}, method=RequestMethod.POST, consumes="application/json")
public ResponseEntity<Void> handlePostServiceId(final InputStream requestInputStream,
#PathVariable String serviceId,
final HttpServletRequest servletRequest,) {
<$businessLogic>
return new ResponseEntity<>(new HttpHeaders(), HttpStatus.ACCEPTED);
}
I can get it to return utf-8 if I include produces= MediaType.APPLICATION_JSON_UTF8_VALUE in my #RequestMapping but I would like to only have to set that once, rather than for every single API.
I also tried adding
#Override
public void configureContentNegotiation(
ContentNegotiationConfigurer configurer) {
configurer.defaultContentType(MediaType.APPLICATION_JSON_UTF8_VALUE);
}
to my WebMvcConfigurer as suggested here: https://stackoverflow.com/a/25275291/2855921 but that broke my availability api which consumes plain/text content type.
I also ensured that my request was UTF-8, so it is not just mirroring back the format I gave.
Any ideas on how I can set the charset to be UTF-8 for the entire project?

Answer 1

Add the below properties to the application.properties file:
For Spring Boot 1.x
# Charset of HTTP requests and responses. Added to the "Content-Type"
# header if not set explicitly.
spring.http.encoding.charset=UTF-8
# Enable http encoding support.
spring.http.encoding.enabled=true
# Force the encoding to the configured charset on HTTP requests and responses.
spring.http.encoding.force=true
Source: https://docs.spring.io/spring-boot/docs/1.5.22.RELEASE/reference/html/common-application-properties.html
For Spring Boot 2.x
server.servlet.encoding.charset=UTF-8
server.servlet.encoding.force-response=true
Source: https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-application-properties.html#server.servlet.encoding.charset

Answer 2

If you're using default object mapper (Jackson) then the encoding can be forced with this simple configuration:
#Bean
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
jsonConverter.setDefaultCharset(StandardCharsets.UTF_8);
return jsonConverter;
}
Here the MappingJackson2HttpMessageConverter() constructor uses public Jackson2ObjectMapperBuilder class to set default parameters for an object mapper.
For another object mapper (Gson or Jsonb) you can look into AllEncompassingFormHttpMessageConverter() constructor.
Note also MediaType.APPLICATION_JSON_UTF8 was deprecated in favor of MediaType.APPLICATION_JSON since Spring 5.2.
So in tests I prefer to use contentTypeCompatibleWith(...) instead of contentType(..._UTF8):
MvcResult result = mockMvc.perform(get("/api/resource"))
.andDo(print())
.andExpect(status().isOk())
// .andExpect(content().contentType(MediaType.APPLICATION_JSON_UTF8))
.andExpect(content().contentTypeCompatibleWith(MediaType.APPLICATION_JSON))
.andReturn();
Links:
Commit where APPLICATION_JSON_UTF8 was replaced by APPLICATION_JSON in MappingJackson2HttpMessageConverter — https://github.com/spring-projects/spring-framework/commit/c38542739734c15e84a28ecc5f575127f25d310a
Chromium issue discussing "Content-Type: application/json" support —https://bugs.chromium.org/p/chromium/issues/detail?id=438464
No "charset" for "Content-Type: application/json" in RFC7159 — https://www.rfc-editor.org/rfc/rfc7159#section-11
More examples with MappingJackson2HttpMessageConverter:
Customizing HttpMessageConverters with Spring Boot and Spring MVC — https://dzone.com/articles/customizing
Http Message Converters with the Spring Framework — https://www.baeldung.com/spring-httpmessageconverter-rest