<!-- Spring mvc4 註解@responsebody返回json時，去掉null值 -->
<mvc:annotation-driven>
<mvc:message-converters>
<bean
class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<beans:property name="objectMapper">
<beans:bean class="com.fasterxml.jackson.databind.ObjectMapper">
<beans:property name="serializationInclusion">
<util:constant
static-field="com.fasterxml.jackson.annotation.JsonInclude.Include.NON_NULL" />
</beans:property>
</beans:bean>
</beans:property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>