mvc interceptors requestbody always empty

Hi experts,

To support multi language, I use mvc:interceptors

Code:

---

<mvc:interceptors> 
        <bean class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor">
              <property name="paramName" value="lang"></property>
        </bean>
</mvc:interceptors>

---

It works as well as my expectation.

To post data from UI to server by AJAX, i have this controller:

Code:

---

@RequestMapping(value = "/something", method = RequestMethod.POST)
public void saveData(@RequestBody String body) throws IOException {
  //do something here
}

---

My controller works, but the body is always empty

I don't know why my body is always empty, if I remove the i18n config, my controller work well.

Please tell me why and how to fix this bug.

Thank you.