spring mvc返回json格式配置要求

The resource identified by this request is only capable of generating responses with characteristics not acceptable according to the

返回406，此时要修改。
返回如果是string的json是没有问题的，
但是如果返回对象的json，就得添加如下的配置

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">

   <property name="messageConverters">

   <list>

   <ref bean="jsonHttpMessageConverter"/>

   </list>

   </property>

</bean>

<bean id="jsonHttpMessageConverter" 

       class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>