网上抄的老的配置信息：

---

<mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
        <bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
            <property name="supportedMediaTypes">
                <list>
                    <value>text/html;charset=UTF-8</value>
                    <value>application/json</value>
                    <value>application/xml;charset=UTF-8</value>
                </list>
            </property>
            <property name="features">
                <list>
                <!-- 默认的意思就是不配置这个属性，配置了就不是默认了 -->
                   <!-- 是否输出值为null的字段 ，默认是false-->

                    <value>WriteMapNullValue</value>

                    <value>WriteNullNumberAsZero</value>
                    <value>WriteNullListAsEmpty</value>
                    <value>WriteNullStringAsEmpty</value>
                    <value>WriteNullBooleanAsFalse</value>
                    <value>WriteDateUseDateFormat</value>

                </list>
            </property>
        </bean>

 </mvc:message-converters>
</mvc:annotation-driven>

但是我们拷贝过去后发现，已经被弃用

于是我打开 FastJsonHttpMessageConverter这个类

所以，我们需要这么配置：

<bean name="fastJsonConfig" class="com.alibaba.fastjson.support.config.FastJsonConfig">
	<property name="serializerFeatures">
		<list>
			<value>WriteMapNullValue</value>
			<value>WriteMapNullValue</value>

			<value>WriteNullNumberAsZero</value>
			<value>WriteNullListAsEmpty</value>
			<value>WriteNullStringAsEmpty</value>
			<value>WriteNullBooleanAsFalse</value>
			<value>WriteDateUseDateFormat</value>
		</list>
	</property>
</bean>
<mvc:annotation-driven >
	<mvc:message-converters>

		<!-- 这里配置alibaba 的fastjson -->
		<bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
			<property name="supportedMediaTypes">
				<list>
					<value>text/html;charset=UTF-8</value>
					<value>application/json;charset=UTF-8</value>
				</list>
			</property>

			<!-- 配置 -->
			<property name="fastJsonConfig" ref="fastJsonConfig">

			</property>

		</bean>
	</mvc:message-converters>
</mvc:annotation-driven>