Do welcome files need to exist?
The welcome file mechanism allows a request to /some/directory/ to be served by the contents of a file like /some/directory/index.html.
If there is a servlet mapped to handle the welcome file, it will be called. So if index.jsp is configured as a welcome file, then a request to /some/directory/ will be passed to the JspServlet mapped at
*.jsp to handle the /some/directory/index.jsp file.
However, the file MUST exist for the welcome file mechanism to work. Even if index.do is defined as a welcome file, then a request to /some/directory/ will not be passed to a servlet handling
*.do for some/directory/index.do UNLESS THE FILE EXISTS.
If you want an index to be served by a servlet, then I suggest you use a filter
to do the redirection. See the WelcomeFilter.java for an example.