方法一、在注解@RequestMapping 中添加 produces = {"application/json;charset=UTF-8"}
方法二、在配置文件中添加：
<mvc:annotation-driven>
<!-- 解决返回String时乱码 -->
<mvc:message-converters register-defaults="true">
<bean class="org.springframework.http.converter.StringHttpMessageConverter">
<property name="supportedMediaTypes">
<list>
<value>text/plain;charset=UTF-8</value>
<value>text/html;charset=UTF-8</value>
</list>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
原文：http://www.cnblogs.com/sishengchao/p/5977427.html