This is my way to setup Servlet as welcome page.
I share for whom concern.
web.xml
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>Demo</servlet-name>
<servlet-class>servlet.Demo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Demo</servlet-name>
<url-pattern></url-pattern>
</servlet-mapping>
Servlet class
@WebServlet(name = "/demo")
public class Demo extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
RequestDispatcher rd = req.getRequestDispatcher("index.jsp");
}
}