<context:annotation-config> declares support for general annotations such as @Required, @Autowired, @PostConstruct, and so on.
<mvc:annotation-driven /> is actually rather pointless. It declares explicit support for annotation-driven MVC controllers (i.e.@RequestMapping, @Controller, etc), even though support for those is the default behaviour.
My advice is to always declare <context:annotation-config>, but don‘t bother with <mvc:annotation-driven /> unless you want JSON support via Jackson.
当我们需要controller返回一个map的json对象时，可以设定<mvc:annotation-driven />，
同时设定<mvc:message-converters> 标签，设定字符集和json处理类，例如：
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/plain;charset=UTF-8</value>
</list>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>