Even if it is possible, use this with extreme caution since the server may be using a custom superclass already

Use superclass attribute of the <%@ page %> directive

It is not possible to change superclass of servlets generated from JSP pages

It is possible but implementation depends on a servlet container.

Use extends attribute of the <%@ page %> directive

Use superclass tag in the deployment descriptor file

The possibility of changing JSP servlet superclass depends on capabilities of the servlet container.
So there is no common way to do it.