This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
most of the servlet container use it's own JSP Super class for its convenient. if you explicitly use any other class then you may get into trouble to run or compile that.
i think most cases you really not required extends attribute.