J2EE Web FundamentalsLesson 7
JSP
Instructor: Dr. Segun Adekile
Outline
• Objectives• Course Text Book– Basham, Bryan; Sierra, Kathy; Bates, Bert (2012-
10-30). Head First Servlets and JSP (Kindle Location 1349). O'Reilly Media. Kindle Edition.
• Using JSP:– Being a JSP
Objectives
Agenda• Introduction
– Why JSPs?– What is a JSP?
• Page Directive• JSP Element: Expressions• JSP Element: Declarations• Implicit Objects• Comments• Standard Actions• Expression Language• JSTL• Custom Tag Development
Why JSPs?
What is a JSP?
• A JSP is a servlet
What is a JSP?
• In the end, a JSP is just a servlet• Your JSP eventually becomes a full-fledged servlet running in your web
app. • It’s a lot like any other servlet, except that the servlet class is written for
you — by the Container. • The Container takes what you’ve written in your JSP, translates it into a
servlet class source (. java) file, then compiles that into a Java servlet class. • After that, it’s just servlets all the way down, and the servlet runs in
exactly the same way it would if you’d written and compiled the code yourself.
• In other words, the Container loads the servlet class, instantiates and initializes it, makes a separate thread for each request, and calls the servlet’s service() method.
A Simple JSP
Page Directive
Expressions
Declarations
Declarations
Declarations
Declarations
Generated Servlet
Generated Servlet
Implicit Objects
Comments
API for JSP Servlet
Lifecycle of a JSP
Lifecycle of a JSP
Initializing JSP
Attributes in a JSP
Three Directives
Page Directive attributes
Page Directive attributes
Scriptlets considered harmful?
Expression Language
Recap