使用jFinal，不会配置默认欢迎页面

现在我写了一个小的javaweb项目，想打出http://localhost:8080/tree就能访问tree->webroot->index.html，但是我在web.xml中配置了欢迎页信息也依然不行，总是404.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
       <welcome-file-list>
       <welcome-file>index.html</welcome-file>
     </welcome-file-list>
  <display-name>tree</display-name>
  <filter>
      <filter-name>jfinal</filter-name>
      <filter-class>com.jfinal.core.JFinalFilter</filter-class>
      <init-param>
          <param-name>configClass</param-name>
          <param-value>com.tree.config.DefaultConfig</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>jfinal</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

把过滤映射的注释掉可以自动进入欢迎页，但是那样项目的功能就没法用了

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
       <welcome-file-list>
       <welcome-file>index.html</welcome-file>
     </welcome-file-list>
  <display-name>tree</display-name>
  <filter>
      <filter-name>jfinal</filter-name>
      <filter-class>com.jfinal.core.JFinalFilter</filter-class>
      <init-param>
          <param-name>configClass</param-name>
          <param-value>com.tree.config.DefaultConfig</param-value>
      </init-param>
  </filter>
<!--   <filter-mapping>注释掉
      <filter-name>jfinal</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping> -->
</web-app>

请大神解难。。