index.jsp (EXT) in the root directory of Tomcat __js

Tomcat has been in use for more than a year, has not been carefully studied its default page how to come out, today boring research a bit. At first, it was thought that Tomcat's starting file was index.jsp in the root directory, but when I deleted index.jsp I found that the default page was still available, and then I looked at the Root/web-inf under classes and Lib under the drum, Discover that both are org.apache.jsp.index_jsp.class, and then I looked back at it, so it hard-coded the contents of the index.jsp into this file. And look at the Web.xml file.
<servlet>
<servlet-name>org.apache.jsp.index_jsp</servlet-name>
<servlet-class>org.apache.jsp.index_jsp</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>org.apache.jsp.index_jsp</servlet-name>
<url-pattern>/index.jsp</url-pattern>
</servlet-mapping>
So, because the tomcat default starting file is index.jsp and index.htm, this is not the default Start page mapping to the Org.apache.jsp.index_jsp class, so I deleted this paragraph, You can go straight to the index.jsp, haha.