JSP & Servlet Life Cycle Kevin Nilson http://www.javaclimber.com Interview Presentation for: Part-time - Computer and Information Science Instructor, Monday December 19th, 2005 Additional Resources JavaTM 2 Platform Enterprise Edition, v 1.4 API Specification Packages, Sun Microsystems Story of a Servlet: An Instant Tutorial, Sun Microsystems Ant JSPC Java Servlet Programming, O'Reilly, Chapter 3: The Servlet Life Cycle The J2EE 1.4 Tutorial, Sun Microsystems JSP to Servlet Source Code Generation (Translation) Container Generates Servlet Source Code from JSP Source is often generated & compiled once upon first request (Tomcat) Source is generated & compiled at deployment Source is often generated (Translation) & compiled before deployment(JSPC) Hello World

Hello World!!!


Today is <%=new java.util.Date()%> ]]> *** public abstract class HttpJspBase extends javax.servlet.http.HttpServlet implements javax.servlet.jsp.HttpJspPage Servlet Life Cycle Overview constructor init service destroy Constructor Typically not used Container may call on startup or with first request One Servlet instance or a pool handles all requests Init Called right before first request is processed Used for one time initializations: Reading & loading configuration ??? jspInit( ) in JSP Service Called with every request service handles request and delegates to other methods: doPost, doGet, ...??? doPost handles POST request doGet handles GET request _jspService(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) in JSP, body of JSP Destroy Called once when finished using Servlet Used to clean up resources jspDestroy( ) in JSP Session Management HTTPSession Creation JSP On request it will create an instance of HTTPSession for the user if one does not exist If you do not want an instance of HTTPSession to be created use: <%@ page session="false" %> Servlet On request it will not create an instance of HTTPSession HTTPSession can be created with request.getSession( ) or request.getSession(true) Review
JSP & Servlet UML1 JSP & Servlet UML2
Essay Questions What is the purpose of init and destroy? When is a JSP converted to a Servlet? When are HTTPSession Instances created? When are the steps in the Servlet Life Cycle? Thank You Any Questions? Feel Free to contact me anytime at http://www.javaclimber.com How was this presentation made? DocBook According to the official DocBook web site,
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