1 2     <filter-mapping>
3         <filter-name>FilterDemo3</filter-name>
4         <url-pattern>/*</url-pattern>
5         <dispatcher>REQUEST</dispatcher> 默认情况。如果写了另外一种情况，默认的就没有了
6         <dispatcher>FORWARD</dispatcher>
7         <dispatcher>INCLUDE</dispatcher>
8         <dispatcher>ERROR</dispatcher>
9       </filter-mapping>