Spring MVC中用@ResponseBody轉json，對json進行處理方法匯總

    <mvc:annotation-driven>
        <mvc:message-converters register-defaults="true">
            <bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
                <property name="features">
                    <array>
                        <!-- 下面配置，默認是false-->
                        <value>WriteMapNullValue</value>
                        <value>WriteNullNumberAsZero</value>
                        <value>WriteNullListAsEmpty</value>
                        <value>WriteNullStringAsEmpty</value>
                        <value>WriteNullBooleanAsFalse</value>
                        <value>WriteDateUseDateFormat</value>
                    </array>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>