2. What is this JSP anyway !?
JavaServer Pages (JSP) is a java technology that provides a simplified,
fast way to create dynamic web content. JSP technology enables rapid
development of web-based applications that are server- and platform-
independent.
It helps software developers serve dynamically generated web pages
based on HTML, XML, or other document types. Released in 1999 as Sun's
answer to ASP and PHP, JSP Specification was designed to address the
perception that the Java programming environment didn't provide
developers with enough support for the Web.
JSP , like other Java APIs, is a specification by Sun for vendors to
implement. The JSP specification builds on the functionality provided by the
servlet specification
Biswabrata Banerjee
3. • A sample JSP page (code ref-1.1):-
Today.jsp
<%@ page import=“java.util.Date”%>
<html>
<body>
The Current Date and Time is:
<%=(new Date()).toString()) %>
</body>
</html>
Biswabrata Banerjee
7. • No central component
• Has to embed Big chunk of Java-code to implement
business logic
• Designers aren’t comfortable with server-side
programmig.
• Reusability of application components are is not
promoted.
Biswabrata Banerjee
9. MVC Architecture Explained …
In MVC model, the request is sent by the browser to the controller or the servlet. This
request is instantiated by the servlet as a Java Bean. The main aspect is JSP are compiled
into servlets at the back end and the front end tasks are not interrupted. The servlet engine
takes up the responsibility of compiling JSP Servlet and producing the final JSP servlet class
for usage. The front end presentation modules are handled by JSP for viewing and the
manipulation of data is handled by Java Bean(model) and passed back to JSP when
needed. The Presentation part of the MVC Model has no processing logic. It performs the
task of extracting beans or objects that may have been initially created by the controller. It
also extracts the dynamic content within for insertion within its static templates.
The Application Manager in the MVC Model is the Controller that processes HTTP
requests. They are not responsible for presentation tasks. That can be either servlets or JSP.
They take the task of managing the application state, security, and presentation uniformity
and thus, have a single point of entry.
10. JSP Life-cycle
Phase Name Description
Page Translation A Servlet (java) file is created
Page compilation The java file compiled.
Load class Compiled class loaded
Create Instance An instance of Servlet is created
Call jspInit() This method is called before other method to allow
Syn : public void jspInit() { //.. } initialization.
Call _jspService() This method is called for each request
Syn : public void _jspService(HttpServletRequest req,
HttpServletResponse res )
throws ServletException,IOException { //..}
Call jspDestory() This method is called when Servlet decided to take the
Syn : public void jspDestroy() { //.. } Servlet out of service
11. // not exact code ! Depends on vendor specification.
import java.util.Date;
public final class Todat_jsp implements javax.servlet.Servlet,
javax.servlet.jsp.HttpJspPage {
public void jspInit(){
// initialization parameters
}
public void _jspService( javax.servlet.http.HttpServletRequest request,
javax.servlet.http.HttpServletResponse response )
throws javax.servlet.ServletException , java.io.IOException
{
javax.servlet.ServletConfig config = …; // Get the servlet config
out.wite( (new Date().toString() ) ;
}
public void jspDestroy(){
// …
}
}
12. JSP Nuts & Bolts
page
Directives include Comments
Expression
taglib Scriptlet
Declaration
Scripting Elements
Actions
getProperty include plugin
useBean
setProperty param forward
13. Attribute Description Default value
language For defining scripting language java
extends To indicate which clas the generated servlet will Omitted
extend
Import Reason is Same as import in a java class Omitted
session specify whether a page participates in a session True
buffer models Buffer for the output stream of the client Implementation
dependent;at least 8kb
autoFlush To empty the buffer if full True
isThreadSafe Defines the level of thread safety true
Info Defines an informative string [ servlet.getServletInfo() ] Omitted
errorPage To invoke another JSP page on error Omitted
isErrorPage If this is an error page of some other JSP page false
contentType The character encoding & MIME (Multipurpose MIME type is text/html
Internet Mail Extensions) type. CHARSET is ISO-8859-1
15. The include directive
Include Directive Includes a file of text or code when the JSP
page is translated i.e., at the time of compilation.
JSP Syntax
<%@ include file="relativeURL" %>
Examples
include.jsp:
<html>
<head><title>An Include Test</title></head>
<body bgcolor="white">
<font color="blue">
The current date and time are
<%@ include file="date.jsp" %>
</font>
</body>
</html>
16. The include directive … Cont’d
date.jsp:
<%@ page import="java.util.*" %>
<%= (new java.util.Date() ).toLocaleString() %>
Displays in the page:
The current date and time are
Aug 30, 1999 2:38:40
Description
The <%@ include %> directive inserts a file of text or code in a JSP file at
translation time, when the JSP file is compiled. When you use the <%@ include %>
directive, the include process is static. A static include means that the text of the
included file is added to the JSP file. The included file can be a JSP file, HTML file,
or text file. If the included file is a JSP file, its JSP elements are parsed and their
results included (along with any other text) in the JSP file.
17. The taglib directive
Taglib Directive defines a tag library and prefix for the custom
tags used in the JSP page.
JSP Syntax
<%@ taglib uri="URIToTagLibrary" prefix="tagPrefix" %>
Examples
<%@ taglib uri="http://www.jspcentral.com/tags" prefix="public" %>
<public:loop>
</public:loop>
Description
The <%@ taglib %> directive declares that the JSP file uses custom
tags, names the tag library that defines them, and specifies their
tag prefix.
