1. 추가파일
jsckson-all-1.9.8.jar

2. bean 설정
 <bean id="handlerMapping"
  class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"
  p:alwaysUseFullPath="true" />
 <bean
  class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"
  p:alwaysUseFullPath="true">
  <property name="messageConverters">
   <list>
    <bean
     class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"></bean>
   </list>
  </property>
 </bean>

3. 임의의 오브젝트를 넘기면 알아서 JSON으로 반환한다.
@RequestMapping("/hello")
 @ResponseBody
    public List hello() throws Exception {
  
  //현재 요청중인 thread local의 HttpServletRequest 객체 가져오기
   HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
   //HttpSession 객체 가져오기
   HttpSession session = request.getSession();
   //ServletContext 객체 가져오기
   ServletContext conext = session.getServletContext();
  WebApplicationContext wContext = WebApplicationContextUtils.getWebApplicationContext(conext);
   //스프링 빈 가져오기 & casting
  EmpDao sBean = (EmpDao)wContext.getBean("EmpDao");
   List ss = (List)sBean.getNames();
        return ss;
    }