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Java Server Pages
Agenda
• CGI• Servlet• What is JSP ?• JSP Processing• JSP elements• How to use beans with JSP ?
Agenda
• CGI• Servlet• What is JSP ?• JSP Processing• JSP elements• How to use beans with JSP ?
CGI
Agenda
• CGI• Servlet• What is JSP ?• JSP Processing• JSP elements• How to use beans with JSP ?
Servlet• Servlets are java
programs that run on web servers.
• Servlets have benefits
that are platform independent, portable.
How Servlet works?
Browser Web Server
.javafiles
Operating System
Operating System
HTTP Request
HTML ServletEngine
DataFiles
JVM
Agenda
• CGI• Servlet• What is JSP ?• JSP Processing• JSP elements• How to use beans with JSP ?
What is JSP ?• JavaServer Pages is a java-based technology
for developing web pages that include dynamic content.
o based on user input, time of day, or any other runtime conditions.
• A JSP page is a HTML pages with JSP elements for generating the parts of the page that differ for each request.
Agenda
• CGI• Servlet• What is JSP ?
• JSP Processing• JSP elements• How to use beans with JSP ?
JSP Processing
Agenda
• CGI• Servlet• What is JSP ?• JSP Processing• JSP elements• How to use beans with JSP ?
JSP Elements
1. Comments2. Scripting Elements
• Scriptlets• Expressions• Declarations
3. Directives4. Actions
JSP Comment
• HTML comment will appear in the output stream to the browser <!-- comments … -- >
• JSP comment will not be processed by the JSP compiler <%-- comments … --%>
Scripting Elements
1. Scriptlets2. Expressions3. Declarations
<% Scriptlets %>
• A Scriptlet element is simply a section of Java code encapsulated within the opening and closing standard JSP tags.
• JSP Syntax: <% code %>
<% Example %>
<%= Expressions %>
• An Expression element is a Java language expression whose value is evaluated and returned as a string to the page.
• JSP Syntax: <%= code %>
<%= Example %>
<%! Declarations %>
• A Declaration element is used to declare methods and variables that are initialized with the page.
• JSP Syntax: <%! code %>
<%! Example %>
Directives
• JSP directives are used to send messages to the JSP engine.
• Directives general syntax • <%@ directive attribute=“value”%>
» The Page Directive» The Include Directive» The Taglib Directive
<%@ Page %>
• Used for importing classes and setting up content type.
• EX:imports the java.utilCalendar class
• <%@ page import="java.util.Calendar" %>
sets the contentType• <%@ page contentType="text/html" %>
<%@ include %>
• Used for inserting a file to the servlet when the JSP page is translated to a servlet.
• EX:• <%@ include file="footer.jsp" %>• <%@include file =
"/products/examples/listing.html" %>
<%@ Taglib %>
• It tells the JSP engine that this JSP page uses a tag library.
• It specifies the location of a special jar file containing a Tag Library Descriptor.
• EX:• <%@ taglib
uri="http://www.javadesktop.com/sampletags.jar"
prefix="sample" %>• <sample:tagAction> This is an example
</sample:tagAction>
Actions
• Ex:• <jsp:useBean> imports a JavaBeans
component.• <jsp:getProperty> gets a property value
and adds it to the response.• <jsp:setProperty> sets a property value.
Agenda
• CGI• Servlet• What is JSP ?• JSP Processing• JSP elements
• How to use beans with JSP ?
What Is a Bean?
• JavaBeans are regular Java classes designed according to the set of guidelines
defined by the JavaBeans specification
Bean properties • A bean class must have a no-argument constructor.• The bean class should implement the
java.io.Serializable .• Data held by a bean is referred to as the bean's
properties.• The property name is case-sensitive and always starts
with a lowercase letter.• A property is either read-only, write-only or read/write,
and has a value corresponding to a specific Java data type (for instance String,java.util.Date, or int).
Bean properties Cont.
• The bean properties are accessed through (accessor methods ) getter and setter methods.
• Getter and setter method names are composed of the word get or set, respectively, plus the property name, with the first character of each word capitalized.
• A getter method has no arguments and returns a value of the property's type, while
• a setter method takes a single argument of the property's type and has a void return type.
Bean Example
Declaring a Bean in a JSP Page ?
• Before you use a bean in a page, you must tell the JSP container which type of bean it is and associate it with a name: in other words, you must declare the bean.
basic tags for working with Beans
• JSP provide three basic tags for working with Beans :
–<jsp:useBean >–<jsp:setProperty >–<jsp:getProperty >
• These three tags are JSP standard actions.
<jsp:useBean >
• <jsp:useBean id=“bean name” class=“bean class”/>
• EX:
• <jsp:useBean id="cartoon" class="com.ora.jsp.beans.motd.CartoonBean" />
<jsp:setProperty >
• <jsp:setProperty name = “id” property =“someProperty” value=“someValue”/>
– id = the name of the bean as specified in the useBean tag. –property = name of the property to be passed to
the bean. –value = value of that particular property
• EX:• <jsp:setProperty name=" cartoon " property="
fileName“ value=“Books" />
<jsp:getProperty >
• <jsp:getProperty name = “id” property = “someProperty” />
• This action obtains the current value of a bean property and inserts it directly into the response body.
• EX:• <jsp:getProperty name="cartoon"
property="fileName" />
Example
Demos
Question?
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