Advance java session 9
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Working with Java Server Pages discusses JSP, a template page technology that provides a high-level abstraction of servlets. JSP pages allow for separation of presentation from logic while still enabling non-Java programmers to create pages easily. JSP pages get translated into servlets, with the servlet handling each request. The JSP lifecycle includes translation, compilation, class loading, and execution phases. Key benefits of JSP include simplicity, platform independence, and ease of learning compared to technologies like PHP and ASP.
Advance java session 9
- 1. Working with Java Server Pages
- 2. Agenda • Understand the need for Java Server pages • Evaluating the benefits of Java Server pages(JSP) • Understanding JSP Lifecycle • Installing JSP pages
- 3. Need for JSP • JSP is a template page technology - High level abstraction of Servlets • Separation of presentation from logic • Even non java programmer can create JSP pages with reasonable ease
- 4. JSP Introduction • Idea: - Use regular HTML for most of page - Mark servlet code with special tags - Entire JSP page gets translated into a servlet (once), and - servlet is what actually gets invoked (for each request) • Example: <!DOCTYPE …><HTML><HEAD><TITLE>Order Confirmation</TITLE> <LINK REL=STYLESHEET HREF="JSP-Styles.css” TYPE="text/css"> </HEAD><BODY><H2>Order Confirmation</H2> Thanks for ordering <I><%= request.getParameter("title") %></I>! </BODY></HTML>
- 5. JSP lifeCycle • Translation - JSP page is translated into a Servlet by JSP container • Compilation - The generated file is compiled into a servlet. • Class Loading - The generated Servlet is then loaded in the container • Execution - The loaded JSP is executing by the container in response to request and calling the lifecycle methods
- 6. JSP lifeCycle(cont) • Initialization - JspInit() method is called immediately after the instance was created. • _jspService() execution - This method is called for every request of the JSP during lifecycle - This method cannot be overridden by the page author • jspDestroy() - This method is called when the jsp is destroyed. • jspInit(),_jspService(), jspDestroy() are the lifecycle methods of JSP
- 7. Benefits of JSP • Simple to use • Requires little of no knowledge of java • Platform independent (built of java) • Easy to learn and migrate being similar to PHP and ASP • Well Documented
- 8. Installing JSP • JSP is part of JEE specification • It’s library is available in all the JEE compliant Server • We need to create JSP File in the context-root • No need to - set classpath - Compile - Configure xml
- 9. Summary • JSP makes it easier to create and maintain HTML, while still providing full access to servlet code • JSP pages get translated into servlets - It is the servlets that run at request time - Client does not see anything JSP-related • You still need to understand servlets - Understanding how JSP really works - Servlet code called from JSP - Knowing when servlets are better than JSP - Mixing servlets and JSP • Other technologies use similar approach, but aren't as portable and don't let you use Java for the "real code