<!-- 拦截设置 -->
<servlet-mapping>
  <servlet-name>dispatcherServlet</servlet-name>
  <url-pattern>/</url-pattern>
</servlet-mapping>

<!-- /user/login是Controller中的方法 -->

<servlet-mapping>
  <servlet-name>dispatcherServlet</servlet-name>
  <url-pattern>/user/login</url-pattern>
</servlet-mapping>
<welcome-file-list>
  <welcome-file>user/login</welcome-file>
</welcome-file-list>