spring乱码过滤器不起作用

spring乱码过滤器配置如下：

<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>

运行项目时出现了乱码，发现该过滤器没有起作用，解决办法是将第15行代码改成如下即可：

<url-pattern>/*</url-pattern>

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