Who sets response content-type in Spring MVC (@ResponseBody)

I found solution for Spring 3.1. with using @ResponseBody annotation.Here is example of controller using Json output:

@RequestMapping(value = "/getDealers", method = RequestMethod.GET, produces = "application/json; charset=utf-8")@ResponseBodypublic String sendMobileData() {}

Simple declaration of the StringHttpMessageConverter bean is not enough, you need to inject it into AnnotationMethodHandlerAdapter:

<bean class = "org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">    <property name="messageConverters">        <array>            <bean class = "org.springframework.http.converter.StringHttpMessageConverter">                <property name="supportedMediaTypes" value = "text/plain;charset=UTF-8" />            </bean>        </array>    </property></bean>

However, using this method you have to redefine all HttpMessageConverters, and also it doesn't work with <mvc:annotation-driven />.

So, perhaps the most convenient but ugly method is to intercept instantiation of the AnnotationMethodHandlerAdapter with BeanPostProcessor:

public class EncodingPostProcessor implements BeanPostProcessor {    public Object postProcessBeforeInitialization(Object bean, String name)            throws BeansException {        if (bean instanceof AnnotationMethodHandlerAdapter) {            HttpMessageConverter<?>[] convs = ((AnnotationMethodHandlerAdapter) bean).getMessageConverters();            for (HttpMessageConverter<?> conv: convs) {                if (conv instanceof StringHttpMessageConverter) {                    ((StringHttpMessageConverter) conv).setSupportedMediaTypes(                        Arrays.asList(new MediaType("text", "html",                             Charset.forName("UTF-8"))));                }            }        }        return bean;    }    public Object postProcessAfterInitialization(Object bean, String name)            throws BeansException {        return bean;    }}

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<bean class = "EncodingPostProcessor " />

Note that in Spring MVC 3.1 you can use the MVC namespace to configure message converters:

<mvc:annotation-driven>  <mvc:message-converters register-defaults="true">    <bean class="org.springframework.http.converter.StringHttpMessageConverter">      <property name="supportedMediaTypes" value = "text/plain;charset=UTF-8" />    </bean>  </mvc:message-converters></mvc:annotation-driven>

Or code-based configuration:

@Configuration@EnableWebMvcpublic class WebConfig extends WebMvcConfigurerAdapter {  private static final Charset UTF8 = Charset.forName("UTF-8");  @Override  public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {    StringHttpMessageConverter stringConverter = new StringHttpMessageConverter();    stringConverter.setSupportedMediaTypes(Arrays.asList(new MediaType("text", "plain", UTF8)));    converters.add(stringConverter);    // Add other converters ...  }}