<action name="XXXAjax" class="XXXAction">

   <result type="json">

    <param name="contentType">text/html</param>

   </result>

  </action>

HttpHeaders headers = new HttpHeaders();

        MediaType mt=new MediaType("text","html",Charset.forName("UTF-8"));

        headers.setContentType(mt);

        ResponseEntity<JsonModel> re=null;

        re=new ResponseEntity<JsonModel>(jsonModel,headers, HttpStatus.OK);

        return re;