Every filter defined in web.xml file should be used in a <filter-mapping> element. Otherwise such filters are not invoked.

Noncompliant Code Example

  <filter>
     <filter-name>DefinedNotUsed</filter-name>
     <filter-class>com.myco.servlet.ValidationFilter</filter-class>
  </filter>

Compliant Solution

  <filter>
     <filter-name>ValidationFilter</filter-name>
     <filter-class>com.myco.servlet.ValidationFilter</filter-class>
  </filter>

  <filter-mapping>
     <filter-name>ValidationFilter</filter-name>
     <url-pattern>/*</url-pattern>
  </filter-mapping>

See