J2EE Filter配置项url-pattern与servlet-name

url-pattern根据请求path路径进行过滤，servlet-name根据Servlet名称过滤

<filter>
	<filter-name>CompressingFilter</filter-name>
  <filter-class>
      com.utfs.util.compress.CompressingFilter
    </filter-class>
	</filter>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<url-pattern>*.js</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<url-pattern>*.css</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<url-pattern>*.gif</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<url-pattern>*.png</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<url-pattern>*.jpg</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<servlet-name>UmpDispatcherServlet</servlet-name>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<servlet-name>CodeServlet</servlet-name>
	</filter-mapping>
	<filter-mapping>
		<filter-name>CompressingFilter</filter-name>
		<url-pattern>/app/*</url-pattern>
	</filter-mapping>

另外需要了解，在Filter中除了使用sendRedirect之外无法进行请求转发