配置404

 <!-- 定义默认访问页 -->   <welcome-file-list>    <welcome-file>index.html</welcome-file>    <welcome-file>index.action</welcome-file>   </welcome-file-list>      <!-- 出错页面定义 -->   <error-page>    <exception-type>java.lang.Throwable</exception-type>    <location>/html/error_page.html</location>   </error-page>    <error-page>    <error-code>500</error-code>    <location>/html/error_page_500.html</location>   </error-page>   <error-page>    <error-code>404</error-code>    <location>/html/error_page_404.html</location>   </error-page>   <error-page>    <error-code>403</error-code>    <location>/html/error_page_403.html</location>   </error-page>