看到很多项目里都是用阿里的fastjson，为什么呢？springmvc不是默认有json转换器了吗
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/html;charset=utf-8</value>
<value>application/json</value>
</list>
</property>
<property name="features">
<list>
<value>QuoteFieldNames</value>
</list>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>