解决 POST 请求乱码

在 WEB-INF/web.xml 中配置好 SpringMVC 提供的编码过滤器即可：

<!-- WEB-INF/web.xml -->
<filter>
    <filter-name>characterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>characterEncodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

解决 GET 请求乱码

修改 Tomcat 的 server.xml 文件的 Connector 节点：

<Connector port="8080"  protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" URIEncoding="UTF-8" />