配置编码过滤器

通过类org.springframework.web.filter.CharacterEncodingFilter，定义request和response的编码。具体做法是在web.xml中定义一个Filter，如下：

<filter>
    <filter-name>encodingFilter</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>encodingFilter</filter-name>

    <url-pattern>/*</url-pattern>

</filter-mapping>