How to set MediaType to UTF-8 in restTemplate with json format

Question

I have one problem that I can't convert the data in json format to UTF-8 when the server response. I have set MediaType in spring configuration xml, but it seems not work. And here is my server side code to response:

    @RequestMapping(value = "/post",  method = RequestMethod.POST)
    public @ResponseBody String postData(@RequestBody ObjectNode request){
        // do something with request
        return response;
    }

When server response, data in json format will contain value as unicode. And in client side configuration:

    <bean id="restTemplate" class="org.springframework.web.client.RestTemplate">
      <property name="messageConverters">
        <list>
            <bean id="formConverter" class="org.springframework.http.converter.FormHttpMessageConverter" />
            <bean id="stringConverter" class="org.springframework.http.converter.StringHttpMessageConverter" />
            <bean id="jsonConverter" class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" >
                <property name="supportedMediaTypes">
                      <list>
                        <bean class="org.springframework.http.MediaType">
                           <constructor-arg value="application" />
                           <constructor-arg value="json" />
                           <constructor-arg value="#{T(java.nio.charset.Charset).forName('UTF-8')}"/>
                         </bean>
                      </list>
                </property>
            </bean>
        </list>
      </property>
    </bean>

And here is my client side code to request for data, and I use postForObject method:

    @Autowired
    private RestTemplate restTemplate;

    public ObjectNode postObjectNode(ObjectNode request){
          ObjectNode node = restTemplate.postForObject("http://localhost:8080/server/post", request, ObjectNode.class);
          return node;
}

And as a result, data that contain the unicode will convert to ????. Is it cause by server or cause by restTemplate client. please help me. Thanks in advance...

Solution 1

If the handler method return String type for @ResponseBody, default Message Converter is StringHttpMessageConverter, you can config the converter like this

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

Solution 2

Obviously it's a dirty hack, but Spring forced me to do it :) It works fine in our project. We're calling a method that changes StringHttpMessageConverter.DEFAULT_CHARSET reflectively after context initialization.

Create a class somewhere in your package:

public class CharsetPostProcessor implements InitializingBean, ApplicationContextAware {

    private ApplicationContext applicationContext;

    static void setFinalStatic(Field field, Object newValue) throws Exception {
        field.setAccessible(true);

        Field modifiersField = Field.class.getDeclaredField("modifiers");
        modifiersField.setAccessible(true);
        modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);

        field.set(null, newValue);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    @Override
    public void afterPropertiesSet() throws Exception {

        Field charsetField = applicationContext.getBean("stringHttpMessageConverter").getClass().getField("DEFAULT_CHARSET");
        Charset charset = Charset.forName("UTF-8");
        setFinalStatic(charsetField, charset);
    }
}

And add following into your Spring context definition:

<bean class="your.package.CharsetPostProcessor" />
<bean id="stringHttpMessageConverter" class="org.springframework.http.converter.StringHttpMessageConverter" />

Comments

[chrylis -cautiouslyoptimistic-]

Start by checking the actual return results from the server. I recommend either using telnet to make the HTTP request by hand or using a tool like Wireshark to inspect the HTTP response. This should tell you which end is having trouble.

[Larry.Z]

What's the defalut response content-type? Can you post that?

[Eric]

Thanks for your reply. And I keep my configuration the same but I change from String to ObjectNode when server response. And now it works.

[Larry.Z]

If you want to get json format for spring-mvc controller, return an Object is a good idea, spring convert json format automaticly with the correct charset.