Jsp Presentation +Mufix "3"

Java Server Pages

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


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


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

Question?

Jsp Presentation +Mufix "3"

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