现象：需要在filter标签后添加多个filter-mapping标签，一个url-pattern就对应一个filter-mapping标签，不能直接把多个url-pattern配置到同一个filter-mapping标签里，也不能直接把多个url直接配置到一个url-pattern标签里。正确地配置方式如下所示：

    1. <filter>  
    2.     <filter-name>test</filter-name>  
    3.     <filter-class>com.test.TestFilter</filter-class>  
    4. </filter>  
    5. <filter-mapping>
    6.     <filter-name>test</filter-name>  
    7.     <url-pattern>/test/a/*</url-pattern>  
    8. </filter-mapping>  
    9. <filter-mapping>  
    10.     <filter-name>test</filter-name>  
    11.     <url-pattern>/test/b/*</url-pattern>  
    12. </filter-mapping>