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JavaServer Pages
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Introduction
JavaServer Pages Overview
First JavaServer Page Example
Implicit Objects
Scripting
5.1
Scripting Components
5.2
Scripting Example
6 Standard Actions
6.1
<jsp:include> Action
6.2
<jsp:forward> Action
6.3
<jsp:useBean> Action
7 Directives
7.1
include Directive
7.2
page Directive
7.3
EL and Custom Tag Libraries
8 Servlet and JSP Resources
1 Introduction
•  JavaServer Pages
–  Extension of Servlet technology
•  Web content delivery
•  Reuse existing Java components
–  Without programming Java
•  Create custom tags
–  Encapsulate complex functionality
•  Classes and interfaces specific to JSP
–  Package javax.servlet.jsp
–  Package javax.servlet.jsp.tagext
2 JavaServer Pages Overview (cont.)
•  JSPs
–  Look like standard HTML or XHTML
•  Normally include HTML or XHTML markup
–  Known as fixed-template data
–  Used when content is mostly fixed-template data
•  Small amounts of content generated dynamically (java
code)
•  Servlets
–  Used when small amount of content is fixedtemplate data
•  Most content generated dynamically
2 JavaServer Pages Overview (cont.)
•  Some servlets do not produce content
–  Invoke other servlets and JSPs
•  JSPs execute as part of a Web server
–  JSP container
•  JSP first request
–  JSP container translates a JSP into a servlet
•  Handle the current and future requests
•  Same life cycle as a servlet
–  _jspService method à service method in servlet
–  _jspInit method à init method in servlet
–  _jspDestroy method à destroy method in servlet
Cycle de vie durant la phase d'exécution
3 A First JavaServer Page Example
•  Simple JSP example (Fig. 1)
–  Demonstrates
•  Fixed-template data (XHTML markup)
•  Creating a Java object (java.util.Date)
•  Automatic conversion of JSP expression to a String
•  meta element to refresh Web page at specified interval
–  First invocation of clock.jsp
•  Notice the delay while:
–  JSP container translates the JSP into a servlet
–  JSP container compiles the servlet
–  JSP container executes the servlet
•  Subsequent invocations should not experience the same delay
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 1: clock.jsp -->
Outline
Cock.jsp
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv = "refresh" content = "60" />
<title>A Simple JSP Example</title>
<style type = "text/css">
.big { font-family: helvetica, arial, sans-serif;
font-weight: bold;
font-size: 2em; }
</style>
</head>
<body>
<p class = "big">Simple JSP Example</p>
Line 10
Meta
element
meta element refreshes
the
Web page every 60 seconds
refershes
the Web
page
every 60
seconds.
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<table style = "border: 6px outset;">
<tr>
<td style = "background-color: black;">
<p class = "big" style = "color: cyan;">
<!-- JSP expression to insert date/time -->
<%= new java.util.Date() %>
</p>
</td>
</tr>
</table>
</body>
</html>
Outline
Creates Date object that is
converted to a String
implicitly and displayed in
paragraph (p) element
Clock.jsp
Line 30
Creates
Date
object
Outline
Clock.jsp
DEMO
Utilité des JSP
• 
• 
• 
• 
Création de pages "design"
Analyse de formulaires
Possibilité d’interfaçage avec de "vrais" servlets
Accès à toute classe Java mise à disposition
(notamment des "beans")
4 Implicit Objects
•  Implicit Objects
–  Provide access to many servlet capabilities within a JSP
–  Accessibles depuis la page JSP sans avoir besoin de les déclarer
préalablement
–  Déclarés et crées par le conteneur
–  Four scopes
•  Application scope
–  Objects owned by the container application
–  Any servlet or JSP can manipulate these objects
•  Page scope
–  Objects that exist only in page in which they are defined
–  Each page has its own instance of these objects
•  Request scope
–  Objects exist for duration of client request
–  Objects go out of scope after response sent to client
•  Session scope
–  Objects exist for duration of client’s browsing session
–  Objects go out of scope when client terminates session or when session timeout
occurs
Les objets implicites JSP
objet
signification
HttpServletRequest
request
l'objet à partir duquel on a accès à la requête du
client Web (getParameter, getParameterNames,
getParameterValues)
HttpServletResponse
response
l'objet avec lequel on peut construire la réponse
du serveur Web à son client. Permet de fixer les
entêtes http à envoyer au client Web
JspWriter out
le flux de sortie qui nous permet d'envoyer du
code HTML au client (print, println)
Implicit object Application Scope
Description
application
This javax.servlet.ServletContext object represents the container in which the JSP
executes.
Page Scope
config
This javax.servlet.ServletConfig object represents the JSP configuration options.
As with servlets, configuration options can be specified in a Web application descriptor.
This java.lang.Throwable object represents the exception that is passed to the JSP error
page. This object is available only in a JSP error page.
This javax.servlet.jsp.JspWriter object writes text as part of the response to a
request. This object is used implicitly with JSP expressions and actions that insert string content
in a response.
This java.lang.Object object represents the this reference for the current JSP instance.
exception
out
page
pageContext
response
Request Scope
request
Session Scope
session
Fig. 25.2
This javax.servlet.jsp.PageContext object hides the implementation details of the
underlying servlet and JSP container and provides JSP programmers with access to the implicit
objects discussed in this table.
This object represents the response to the client and is normally an instance of a class that
implements HttpServletResponse (package javax.servlet.http). If a protocol
other than HTTP is used, this object is an instance of a class that implements
javax.servlet.ServletResponse.
This object represents the client request. The object normally is an instance of a class that
implements HttpServletRequest (package javax.servlet.http). If a protocol other
than HTTP is used, this object is an instance of a subclass of javax.servlet.ServletRequest.
This javax.servlet.http.HttpSession object represents the client session
information if such a session has been created. This object is available only in pages that
participate in a session.
JSP implicit objects.
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 4: welcome.jsp -->
<!-- JSP that processes a "get" request containing data. -->
<html xmlns = "http://www.w3.org/1999/xhtml">
<!-- head section of document -->
<head>
<title>Processing "get" requests with data</title>
</head>
<!-- body section of document -->
<body>
<% // begin scriptlet
String name = request.getParameter( "firstName" );
if ( name != null ) {
Use request implicit
object to get parameter
%> <%-- end scriptlet to insert fixed template data --%>
Outline
2 JavaServer Pages Overview
•  Key components
– 
– 
– 
– 
Scriptlets
Directives
Actions
Tag libraries
2 JavaServer Pages Overview (cont.)
•  Scriptlet
–  Also called “Scripting Elements”
–  Enable programmers to insert Java code in JSPs
–  Performs request processing
•  Interacts with page elements and other components to
implement dynamic pages
5.1 Scripting Components
•  JSP scripting components
–  Scriptlets (delimited by <% and %>)
–  Comments
•  JSP comments (delimited by <%-- and --%>)
•  XHTML comments (delimited by <!-- and -->)
•  Java’s comments (delimited by // and /* and */)
–  Expressions (delimited by <%= and %>)
–  Declarations (delimited by <%! And %>)
–  Escape sequences
Expressions
•  Les expressions JSP sont, des expressions Java qui vont être
évaluées à l'intérieur d'un appel de méthode print
•  Une expression commence par les caractères <%= et se termine
par les caractères %>
•  Comme l'expression est placée dans un appel de méthode, il est
interdit de terminer l'expression via un point-virgule
•  Syntaxe: <%=expression%>
•  Equivalent à: out.println(expression) ;
•  Exemple : <%=new Date()%>
•  Equivalent à: out.println(new Date()) ;
Déclarations
•  Dans certains cas, il est nécessaire d'ajouter des méthodes et des attributs à la
servlet qui va être générée (en dehors de la méthode de service).
•  Une construction JSP particulière permet de répondre à ces besoins. Elle
commence par les caractères <%! et se termine, par les caractères %>. Voici un
petit exemple d'utilisation.
•  Exemple:
<%@ page language="java" %>
<HTML>
<HEAD>
<TITLE>Exemple d'utilisation de déclarations JSP</TITLE>
<%! private int userCounter = 0; %>
</HEAD>
<BODY>
<H1 align="center">Exemple d'utilisation de déclarations JSP</H1><P>
Vous êtes le <%= ++userCounter %><SUP>ième</SUP> client du site</P>
</BODY>
<HTML>
5.2 Scripting Example
•  Demonstrate basic scripting capabilities
–  Responding to get requests
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Outline
<!-- Fig. 4: welcome.jsp -->
<!-- JSP that processes a "get" request containing data. -->
<html xmlns = "http://www.w3.org/1999/xhtml">
<!-- head section of document -->
<head>
<title>Processing "get" requests with data</title>
</head>
<!-- body section of document -->
<body>
<% // begin scriptlet
Scriptlets used to
insert Java code
String name = request.getParameter( "firstName" );
if ( name != null ) {
Use request implicit
object to get parameter
%> <%-- end scriptlet to insert fixed template data --%>
welcome.
jsp
Lines 17-23
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<h1>
Hello <%= name %>, <br />
Welcome to JavaServer Pages!
</h1>
JSP expression
<% // continue scriptlet
} // end if
else {
%> <%-- end scriptlet to insert fixed template data --%>
<form action = "welcome.jsp" method = "get">
<p>Type your first name and press Submit</p>
<p><input type = "text" name = "firstName" />
<input type = "submit" value = "Submit" />
</p>
</form>
<% // continue scriptlet
}
// end else
%> <%-- end scriptlet --%>
</body>
</html>
<!-- end XHTML document -->
Outline
Scriptlets used to
insert Java code
welcome.
jsp
Line 26
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and 45-49
Outline
welcome.
jsp
DEMO
2 JavaServer Pages Overview (cont.)
•  Delimited by <jsp:action> and </jsp:action>
•  JSP standard Actions
–  Predefined JSP tags that encapsulate functionality
–  Provide access to common tasks performed in a JSP
•  Including content from other resources
•  Forwarding requests to other resources <jsp:forward>
•  Interacting with JavaBeans
–  Often performed based on information from client request
–  Can be used to create Java objects for use in scriptlets
6 Standard Actions
Action <jsp:include>
<jsp:forward>
<jsp:plugin>
<jsp:param>
JavaBean Manipulation
<jsp:useBean>
Description
Dynamically includes another resource in a JSP. As the JSP executes, the
referenced resource is included and processed.
Forwards request processing to another JSP, servlet or static page. This
action terminates the current JSP’s execution.
Allows a plug-in component to be added to a page in the form of a
browser-specific object or embed HTML element. In the case of a
Java applet, this action enables the downloading and installation of the
Java Plug-in, if it is not already installed on the client computer.
Used with the include, forward and plugin actions to specify
additional name/value pairs of information for use by these actions.
Specifies that the JSP uses a JavaBean instance. This action specifies the
scope of the bean and assigns it an ID that scripting components can use
to manipulate the bean.
<jsp:setProperty>
Sets a property in the specified JavaBean instance. A special feature of
this action is automatic matching of request parameters to bean properties
of the same name.
<jsp:getProperty>
Gets a property in the specified JavaBean instance and converts the result
to a string for output in the response.
Fig. 25.5 JSP standard actions.
6.1 <jsp:include> Action
•  <jsp:include> action
–  E n a b l e s c o n t e n t t o b e
included in a JSP dynamically
Attribute
page
flush
Fig. 25.6
Description
Specifies the relative URI path of the resource
to include. The resource must be part of the
same Web application.
Specifies whether the buffer should be flushed
after the include is performed. In JSP 1.1,
this attribute is required to be true.
Action <jsp:include> attributes.
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<!-- Fig. 7: banner.html
-->
<!-- banner to include in another document -->
<div style = "width: 580px">
<p>
Java(TM), C, C++, Visual Basic(R),
Object Technology, and <br /> Internet and
World Wide Web Programming Training&nbsp;<br />
On-Site Seminars Delivered Worldwide
</p>
<p>
<a href = "mailto:deitel@deitel.com">deitel@deitel.com</a>
<br />978.461.5880<br />12 Clock Tower Place, Suite 200,
Maynard, MA 01754
</p>
</div>
Outline
banner.html
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<!-- Fig. 8: toc.html
-->
<!-- contents to include in another document -->
Outline
<p><a href = "http://www.deitel.com/books/index.html">
Publications/BookStore
</a></p>
<p><a href = "http://www.deitel.com/whatsnew.html">
What's New
</a></p>
<p><a href = "http://www.deitel.com/books/downloads.html">
Downloads/Resources
</a></p>
<p><a href = "http://www.deitel.com/faq/index.html">
FAQ (Frequently Asked Questions)
</a></p>
<p><a href = "http://www.deitel.com/intro.html">
Who we are
</a></p>
toc.html
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<p><a href = "http://www.deitel.com/index.html">
Home Page
</a></p>
Outline
<p>Send questions or comments about this site to
<a href = "mailto:deitel@deitel.com">
deitel@deitel.com
</a><br />
Copyright 1995-2003 by Deitel &amp; Associates, Inc.
All Rights Reserved.
</p>
toc.html
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<!-- Fig. 9: clock2.jsp
-->
<!-- date and time to include in another document -->
Outline
<table>
<tr>
<td style = "background-color: black;">
<p class = "big" style = "color: cyan; font-size: 3em;
font-weight: bold;">
<%-- script to determine client local and --%>
<%-- format date accordingly
--%>
<%
// get client locale
java.util.Locale locale = request.getLocale();
// get DateFormat for client's Locale
java.text.DateFormat dateFormat =
java.text.DateFormat.getDateTimeInstance(
java.text.DateFormat.LONG,
java.text.DateFormat.LONG, locale );
%>
<%-- end script --%>
<%-- output date --%>
<%= dateFormat.format( new java.util.Date() ) %>
</p>
</td>
</tr>
</table>
Use Locale to
format Date
with specified
DateFormat
clock2.j
sp
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Outline
<!-- Fig. 10: include.jsp -->
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>Using jsp:include</title>
<style type = "text/css">
body {
font-family: tahoma, helvetica, arial, sans-serif;
}
table, tr, td {
font-size: .9em;
border: 3px groove;
padding: 5px;
background-color: #dddddd;
}
</style>
</head>
include.
jsp
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<body>
<table>
<tr>
<td style =
<img src
width
alt =
</td>
Outline
"width: 160px; text-align: center">
= "images/logotiny.png"
= "140" height = "93"
"Deitel & Associates, Inc. Logo" />
<td>
<%-- include banner.html in this JSP --%>
<jsp:include page = "banner.html"
flush = "true" />
Use JSP action to
include banner.html
</td>
</tr>
<tr>
<td style = "width: 160px">
<%-- include toc.html in this JSP --%>
<jsp:include page = "toc.html" flush = "true" />
</td>
Use JSP action to
include toc.html
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<td style = "vertical-align: top">
<%-- include clock2.jsp in this JSP --%>
<jsp:include page = "clock2.jsp"
flush = "true" />
</td>
</tr>
</table>
</body>
</html>
Outline
Use JSP action to
include clock2.jsp
Exercice
•  Nous souhaitons reprendre le site de l’EMI avec la
technologie JSP en utilisant l’action Include.
–  Réaliser une Template incluant :
1.  Un Entête de page incluant
1.  Un document html pour le logo de l’école
2.  Un menu horizontal inclus dans toutes les pages
(Accueil, Ecole, Formation, …)
2.  Un Pied de page incluant
1.  Un document html pour Copyright
2.  Un menu horizontal inclus dans toutes les pages
(Accueil, Actualité, Accès-Contacts, Plan du site)
3.  Une zone Incluant le document principal
6.2 <jsp:forward> Action
•  <jsp:forward> action
–  Enables JSP to forward request to different resources
•  Can forwarded requests only resources in same context
•  <jsp:param> action
–  Specifies name/value pairs of information
•  Name/Value pairs are passed to other actions
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Outline
<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 11: forward1.jsp -->
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>Forward request to another JSP</title>
</head>
<body>
<% // begin scriptlet
String name = request.getParameter( "firstName" );
if ( name != null ) {
%> <%-- end scriptlet to insert fixed template data --%>
<jsp:forward page = "forward2.jsp">
<jsp:param name = "date"
value = "<%= new java.util.Date() %>" />
</jsp:forward>
Forward request to
forward2.jsp
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<% // continue scriptlet
Outline
} // end if
else {
%> <%-- end scriptlet to insert fixed template data --%>
<form action = "forward1.jsp" method = "get">
<p>Type your first name and press Submit</p>
<p><input type = "text" name = "firstName" />
<input type = "submit" value = "Submit" />
</p>
</form>
<%
// continue scriptlet
}
// end else
%> <%-- end scriptlet --%>
</body>
</html>
<!-- end XHTML document -->
forward1
.jsp
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Outline
<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- forward2.jsp -->
<html xmlns = "http://www.w3.org/1999/xhtml"v
<head>
<title>Processing a forwarded request</title>
<style type = "text/css">
.big {
font-family: tahoma, helvetica, arial, sans-serif;
font-weight: bold;
font-size: 2em;
}
</style>
</head>
Receive request from
forward1.jsp, then
get firstName
parameter from request
<body>
<p class = "big">
Hello <%= request.getParameter( "firstName" ) %>, <br />
Your request was received <br /> and forwarded at
</p>
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<table style = "border: 6px outset;">
<tr>
<td style = "background-color: black;">
<p class = "big" style = "color: cyan;">
<%= request.getParameter( "date" ) %>
</p>
</td>
</tr>
</table>
</body>
</html>
Outline
Get date parameter
from request
DEMO
6.3 <jsp:useBean> Action
•  <jsp:useBean> action
–  Enables JSP to manipulate Java object
•  Creates Java object or locates an existing object for use in JSP
Attribute id
scope
class
beanName
type
Fig. 25.13
Description
The name used to manipulate the Java object with actions
<jsp:setProperty> and <jsp:getProperty>. A variable of
this name is also declared for use in JSP scripting elements. The name
specified here is case sensitive.
The scope in which the Java object is accessible—page, request,
session or application. The default scope is page.
The fully qualified class name of the Java object.
The name of a bean that can be used with method instantiate of
class java.beans.Beans to load a JavaBean into memory.
The type of the JavaBean. This can be the same type as the class
attribute, a superclass of that type or an interface implemented by that
type. The default value is the same as for attribute class. A
ClassCastException occurs if the Java object is not of the type
specified with attribute type.
Attributes of the <jsp:useBean> action.
6.3 <jsp:useBean> Action (cont.)
Attribute
name
Description
The ID of the JavaBean for which a property (or properties) will be
set.
property
The name of the property to set. Specifying "*" for this attribute
causes the JSP to match the request parameters to the properties of the
bean. For each request parameter that matches (i.e., the name of the
request parameter is identical to the bean’s property name), the
corresponding property in the bean is set to the value of the parameter.
If the value of the request parameter is "", the property value in the
bean remains unchanged.
param
If request parameter names do not match bean property names, this
attribute can be used to specify which request parameter should be
used to obtain the value for a specific bean property. This attribute is
optional. If this attribute is omitted, the request parameter names must
match bean property names.
value
The value to assign to a bean property. The value typically is the result
of a JSP expression. This attribute is particularly useful for setting
bean properties that cannot be set using request parameters. This
attribute is optional. If this attribute is omitted, the JavaBean property
must be of a type that can be set using request parameters.
Fig. 25.16 Attributes of the <jsp:setProperty> action.
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Outline
// Fig. 14: Rotator.java
// A JavaBean that rotates advertisements.
package com.deitel.jhtp5.jsp;
public class Rotator {
private String images[] = { "images/advjHTP1.jpg",
"images/cppHTP4.jpg", "images/iw3HTP2.jpg",
"images/jwsFEP1.jpg", "images/vbnetHTP2.jpg" };
private String links[] = {
"http://www.amazon.com/exec/obidos/ASIN/0130895601/"
"deitelassociatin",
"http://www.amazon.com/exec/obidos/ASIN/0130384747/"
"deitelassociatin",
"http://www.amazon.com/exec/obidos/ASIN/0130308978/"
"deitelassociatin",
"http://www.amazon.com/exec/obidos/ASIN/0130461342/"
"deitelassociatin",
"http://www.amazon.com/exec/obidos/ASIN/0130293636/"
"deitelassociatin" };
private int selectedIndex = 0;
+
+
+
+
+
Rotator.
java
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// returns image file name for current ad
public String getImage()
{
return images[ selectedIndex ];
}
// returns the URL for ad's corresponding Web site
public String getLink()
{
return links[ selectedIndex ];
}
// update selectedIndex so next calls to getImage and
// getLink return a different advertisement
public void nextAd()
{
selectedIndex = ( selectedIndex + 1 ) % images.length;
}
}
Outline
Return image file name
for book cover image
Return hyperlink to
book at Amazon.com
Update Rotator so
subsequent calls to
getImage and getLink
return information for
different advertisements
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Outline
<!-- Fig. 15: adrotator.jsp -->
<jsp:useBean id = "rotator" scope = "application"
class = "com.deitel.jhtp5.jsp.Rotator" />
Use jsp:useBean
action to obtain reference
to Rotator object
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>AdRotator Example</title>
<style type = "text/css">
.big { font-family: helvetica, arial, sans-serif;
font-weight: bold;
font-size: 2em }
</style>
<%-- update advertisement --%>
<% rotator.nextAd(); %>
</head>
Invoke
Rotator’s
nextAd method
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<body>
<p class = "big">AdRotator Example</p>
<p>
<a href = "<jsp:getProperty name = "rotator"
property = "link" />">
<img src = "<jsp:getProperty name = "rotator"
property = "image" />" alt = "advertisement" />
</a>
</p>
</body>
</html>
Outline
Define hyperlink to
Amazon.com site
DEMO
Exercice
•  Créer une classe Personne
•  Créer une classe Groupe composée de plusieurs
personnes
–  Constructeur remplit une ArrayList de personnes
–  Utiliser un index pour se déplacer dans la ArrayList
–  Utiliser un String courant contenant le nom et prénom de
la personne pointée par index
•  Créer une page JSP permettant d’afficher la
personne à chaque mise à jour de la page
7 Directives
•  Directive
–  Message to JSP container
•  i.e., program that compiles/executes JSPs
–  Enable programmers to specify
1.  Content to include from other resources
2.  Page settings
3.  EL and Custom tag libraries used in the JSP
•  Delimited by <%@ and %>
7 Directives (cont.)
Directive
page
Description
Defines page settings for the JSP container to
process (global settings).
include Causes the JSP container to perform a translationtime insertion of another resource’s content. As the
JSP is translated into a servlet and compiled, the
referenced file replaces the include directive and
is translated as if it were originally part of the JSP.
taglib
Allows programmers to define new tags in the form
of tag libraries, which can be used to encapsulate
functionality and simplify the coding of a JSP.
Fig. 25.17 JSP directives.
7.1 include Directive
•  JSP include directive
–  Includes content of another resource at JSP translation time
•  Not as flexible as <jsp:include> action
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 19: includeDirective.jsp -->
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>Using the include directive</title>
<style type = "text/css">
body {
font-family: tahoma, helvetica, arial, sans-serif;
}
table, tr, td {
font-size: .9em;
border: 3px groove;
padding: 5px;
background-color: #dddddd;
}
</style>
</head>
Outline
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<body>
<table>
<tr>
<td style =
<img src
width
alt =
</td>
Outline
"width: 160px; text-align: center">
= "images/logotiny.png"
= "140" height = "93"
"Deitel & Associates, Inc. Logo" />
<td>
<%-- include banner.html in this JSP --%>
<%@ include file = "banner.html" %>
Use include directive to
include banner.html
</td>
</tr>
<tr>
<td style = "width: 160px">
<%-- include toc.html in this JSP --%>
<%@ include file = "toc.html" %>
</td>
Use include directive
to include toc.html
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<td style = "vertical-align: top">
<%-- include clock2.jsp in this JSP --%>
<%@ include file = "clock2.jsp" %>
</td>
</tr>
</table>
</body>
</html>
Outline
Use include directive
to include clock2.jsp
7.1 Exercice
•  Reprendre l’exemple précédent concernant
l’action include avec la directive include
•  Quelles sont les conséquences de ce changement
au niveau :
–  Codage
–  Exécution
7.2 page Directive (cont.)
Attribute language
extends
import
session
Fig. 25.18
Description
The scripting language used in the JSP. Currently, the only valid value
for this attribute is java.
Specifies the class from which the translated JSP will be inherited. This
attribute must be a fully qualified class name.
Specifies a comma-separated list of fully qualified type names and/or
packages that will be used in the current JSP. When the scripting
language is java, the default import list is java.lang.*,
javax.servlet.*, javax.servlet.jsp.* and
javax.servlet.http.*. If multiple import properties are
specified, the package names are placed in a list by the container.
Specifies whether the page participates in a session. The values for this
attribute are true (participates in a session—the default) or false
(does not participate in a session). When the page is part of a session,
implicit object session is available for use in the page. Otherwise,
session is not available, and using session in the scripting code
results in a translation-time error.
Attributes of the page directive.
7.2 page Directive (cont.)
Attribute errorPage
Description
Any exceptions in the current page that are not caught
are sent to the error page for processing. The error page
implicit object exception references the original
exception.
isErrorPage Specifies if the current page is an error page that will be
invoked in response to an error on another page. If the
attribute value is true, the implicit object exception
is created and references the original exception that
occurred. If false (the default), any use of the
exception object in the page results in a translationtime error.
contentType Specifies the MIME type of the data in the response to
the client. The default type is text/html.
Fig. 25.18
Attributes of the page directive.
See GuestBook
example for error page
management
7. 2 Case Study: Guest Book
•  Demonstrate
– 
– 
– 
– 
Action <jsp:setProperty>
JSP page directive
JSP error pages
Use of JDBC
7. 2 Case Study: Guest Book (Cont.)
7. 2 Case Study: Guest Book (Cont.)
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// Fig. 20: GuestBean.java
// JavaBean to store data for a guest in the guest book.
package com.deitel.jhtp5.jsp.beans;
Outline
public class GuestBean {
private String firstName, lastName, email;
// set the guest's first name
public void setFirstName( String name )
{
firstName = name;
}
// get the guest's first name
public String getFirstName()
{
return firstName;
}
// set the guest's last name
public void setLastName( String name )
{
lastName = name;
}
GuestBean defines three
guest properties: firstName,
lastName and email
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// get the guest's last name
public String getLastName()
{
return lastName;
}
Outline
// set the guest's email address
public void setEmail( String address )
{
email = address;
}
// get the guest's email address
public String getEmail()
{
return email;
}
}
GuestBean.java
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Outline
// Fig. 21: GuestDataBean.java
// Class GuestDataBean makes a database connection and supports
// inserting and retrieving data from the database.
package com.deitel.jhtp5.jsp.beans;
// Java core packages
import java.io.*;
import java.sql.*;
import java.util.*;
public class GuestDataBean {
private Connection connection;
private PreparedStatement addRecord, getRecords;
Specify database location
// construct TitlesBean object
public GuestDataBean() throws Exception
{
Load Cloudscape
System.setProperty( "db2j.system.home", "C:/Cloudscape_5.0" );
driver
// load the Cloudscape driver
Class.forName( "com.ibm.db2j.jdbc.DB2jDriver" );
// connect to the database
connection = DriverManager.getConnection(
"jdbc:db2j:guestbook" );
GuestDataBean connects
to guestbook database
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statement = connection.createStatement();
Outline
}
// return an ArrayList of GuestBeans
public ArrayList getGuestList() throws SQLException
{
ArrayList guestList = new ArrayList();
// obtain list of titles
ResultSet results = statement.executeQuery(
"SELECT firstName, lastName, email FROM guests" );
// get row data
while ( results.next() ) {
GuestBean guest = new GuestBean();
guest.setFirstName( results.getString( 1 ) );
guest.setLastName( results.getString( 2 ) );
guest.setEmail( results.getString( 3 ) );
guestList.add( guest );
}
return guestList;
}
GuestDataBean provides
method getGuestList to
manipulate database
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// insert a guest in guestbook database
public void addGuest( GuestBean guest ) throws SQLException
{
statement.executeUpdate( "INSERT INTO guests ( firstName, " +
"lastName, email ) VALUES ( '" + guest.getFirstName() + "', '" +
guest.getLastName() + "', '" + guest.getEmail() + "' )" );
}
// close statements and terminate database connection
protected void finalize()
{
// attempt to close database connection
try {
statement.close();
connection.close();
}
// process SQLException on close operation
catch ( SQLException sqlException ) {
sqlException.printStackTrace();
}
}
}
Outline
GuestDataBean provides
methods addGuest to
manipulate database
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 22: guestBookLogin.jsp -->
<%-- page settings --%>
<%@ page errorPage = "guestBookErrorPage.jsp" %>
page directive defines
information that is
globally available in JSP
Use jsp:useBean
actions to obtain references
to GuestBean and
GuestDataBean objects
<%-- beans used in this JSP --%>
<jsp:useBean id = "guest" scope = "page"
class = "com.deitel.jhtp5.jsp.beans.GuestBean" />
<jsp:useBean id = "guestData" scope = "request"
class = "com.deitel.jhtp5.jsp.beans.GuestDataBean" />
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>Guest Book Login</title>
<style type = "text/css">
body {
font-family: tahoma, helvetica, arial, sans-serif;
}
Outline
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table, tr, td {
font-size: .9em;
border: 3px groove;
padding: 5px;
background-color: #dddddd;
}
</style>
</head>
Outline
<body>
<jsp:setProperty name = "guest" property = "*" />
<% // start scriptlet
if ( guest.getFirstName() == null ||
guest.getLastName() == null ||
guest.getEmail() == null ) {
%> <%-- end scriptlet to insert fixed template data --%>
<form method = "post" action = "guestBookLogin.jsp">
<p>Enter your first name, last name and email
address to register in our guest book.</p>
Set properties of
GuestBean with request
parameter values
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<table>
<tr>
<td>First name</td>
<td>
<input type = "text" name = "firstName" />
</td>
</tr>
<tr>
<td>Last name</td>
<td>
<input type = "text" name = "lastName" />
</td>
</tr>
<tr>
<td>Email</td>
<td>
<input type = "text" name = "email" />
</td>
</tr>
Outline
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<tr>
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<td colspan = "2">
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<input type = "submit"
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value = "Submit" />
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</td>
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</tr>
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</table>
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</form>
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<% // continue scriptlet
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} // end if
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else {
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guestData.addGuest( guest );
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%> <%-- end scriptlet to insert jsp:forward action --%>
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<%-- forward to display guest book contents --%>
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<jsp:forward page = "guestBookView.jsp" />
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<% // continue scriptlet
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} // end else
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%> <%-- end scriptlet --%>
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102</html>
Outline
Forward request to
guestBookView.jsp
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Outline
<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 23: guestBookView.jsp -->
<%-- page settings --%>
<%@ page errorPage = "guestBookErrorPage.jsp" %>
<%@ page import = "java.util.*" %>
<%@ page import = "com.deitel.jhtp5.jsp.beans.*" %>
<%-- GuestDataBean to obtain guest list --%>
<jsp:useBean id = "guestData" scope = "request"
class = "com.deitel.jhtp5.jsp.beans.GuestDataBean" />
Use page directive
import to specify Java
classes and packages that
are used in JSP context
Use jsp:useBean
action to obtain reference
to GuestDataBean
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>Guest List</title>
<style type = "text/css">
body {
font-family: tahoma, helvetica, arial, sans-serif;
}
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table, tr, td, th {
text-align: center;
font-size: .9em;
border: 3px groove;
padding: 5px;
background-color: #dddddd;
}
</style>
</head>
<body>
<p style = "font-size: 2em;">Guest List</p>
<table>
<thead>
<tr>
<th style = "width: 100px;">Last name</th>
<th style = "width: 100px;">First name</th>
<th style = "width: 200px;">Email</th>
</tr>
</thead>
<tbody>
Outline
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<% // start scriptlet
List guestList = guestData.getGuestList();
Iterator guestListIterator = guestList.iterator();
GuestBean guest;
while ( guestListIterator.hasNext() ) {
guest = ( GuestBean ) guestListIterator.next();
%> <%-- end scriptlet; insert fixed template data --%>
<tr>
<td><%= guest.getLastName() %></td>
<td><%= guest.getFirstName() %></td>
<td>
<a href = "mailto:<%= guest.getEmail() %>">
<%= guest.getEmail() %></a>
</td>
</tr>
Outline
Scriptlet displays last
name, first name and email
address for all guests
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<% // continue scriptlet
} // end while
%> <%-- end scriptlet --%>
</tbody>
</table>
</body>
</html>
Outline
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<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!-- Fig. 24: guestBookErrorPage.jsp -->
<%-- page settings --%>
<%@ page isErrorPage = "true" %>
<%@ page import = "java.util.*" %>
<%@ page import = "java.sql.*" %>
<html xmlns = "http://www.w3.org/1999/xhtml">
<head>
<title>Error!</title>
<style type = "text/css">
.bigRed {
font-size: 2em;
color: red;
font-weight: bold;
}
</style>
</head>
Outline
Use page directive
isErrorPage to specify
that guestBookErrorPage is an error page
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Outline
<body>
<p class = "bigRed">
<% // scriptlet to determine exception type
// and output beginning of error message
if ( exception instanceof SQLException )
%>
Use implicit object
exception to determine
error to be displayed
An SQLException
<%
else if ( exception instanceof ClassNotFoundException )
%>
A ClassNotFoundException
<%
else
%>
An exception
<%-- end scriptlet to insert fixed template data --%>
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<%-- continue error message output --%>
occurred while interacting with the guestbook database.
</p>
<p class = "bigRed">
The error message was:<br />
<%= exception.getMessage() %>
</p>
<p class = "bigRed">Please try again later</p>
</body>
</html>
Outline
DEMO
7. 2 Exercice
•  Reprenez l’exemple précédent utilisant la classe Personne
7. 3 Expression language
•  Permet d'accéder plus facilement aux données de
l'application ainsi qu'aux composants JavaBeans
<c:if test="${sessionScope.cart.numberOfItems > 0}">
… </c:if>
•  Ces expressions sont évaluées par le "JSP expression
evaluator"
•  Pour activer/désactiver cette fonctionnalité
<%@page isELIgnored="true|false"% >
•  Destiné à remplacer l'utilisation des scriptlets
7. 3 Comparatif EL / Scriptlet
exemple qui utilise
c:if, c:foreach, request, scope
<center>
<jsp:useBean id= "person" class="Person" />
<%=person.getName()%>
</center>
<center>
${person.name}
</center>
7. 3 Custom Tag Library
•  Custom Tag Library
–  JSP’s tag extension mechanism
–  Enables programmers to define new tags
•  Tags encapsulate complex functionality
•  New tags should be defined in an archive library file
–  Tags can manipulate JSP content
7.3 Custom Tag librairies - Principes
•  Le programmeur définit la syntaxe pour chaque balise et
implémente le comportement associé à chaque balise dans
la classe de gestion des balises (tag handler class)
•  Il décrit ensuite la librairie de balises qu'il vient de créer via
un Tag library descriptor (*.tld)
•  Les auteurs de pages peuvent ensuite importer et utiliser les
balises définies dans les bibliothèques de balises comme
s'ils utilisaient des balises standards
–  Déclaration d'utilisation via
–  Utilisation via
<%@taglib…%>
<%prefix:name….%>
7.3 Custom Tag librairies -Principes
•  Spécifier dans la page JSP qu'on souhaite utiliser
une librairie de balises via la directive
<%@ taglibprefix=”tagPrefix”( uri=”tagLibraryURI”| tagdir=”tagDir”) %>
/WEB-INF/tags/dir
•  On associe à cette déclaration d'utilisation
l'emplacement du fichier de description de la
librairie de balises, fichier *.tld et un préfixe
identifiant la librairie de balises
7.3 Custom Tag librairies - Syntaxe
d'invocation des balises dans les pages JSP
<prefix:tag attr1="value" ... attrN="value" />
<prefix:tag attr1="value" ... attrN="value" >
body
</prefix:tag>
Avec
•  prefix : qui identifie la librairie concernée
•  tag : qui identifie une balise particulière à
l'intérieur de la librairie
•  attr1 ... attrN : qui permet de modifier le
comportement de la balise
7.3 Custom Tag librairies –
Exemple de code JSP
<!DOCTYPE HTML PUBLIC "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
<%@ taglib uri="/WEB-INF/msajsp-taglib.tld" prefix="msajsp"%>
<title> <msajsp:example1 />
</title>
</head>
<body bgcolor="#FFFFFF">
<h1>
<msajsp:example2 />
</h1>
<msajsp:example3/>
</body>
</html>
DEMO
Résumé (scriplet, action, directive)
•  Les données statiques sont transformées en code
d'écriture sur le flot de sortie associé à la réponse
•  Les éléments JSP sont traités différemment
–  Les éléments de scripts sont insérés dans le code de la servlet
issu de la page JSP
–  Les éléments d'action sont convertis en appels de méthodes
sur des composants JavaBean, ou en invocation de l'API
Servlet
–  Les directives sont utilisées pour contrôler la façon dont le
conteneur Web traduit et exécute la page
JSP et Servlet
•  Vous pouvez utiliser le modèle MVC (Modèle Vue Contrôleur).
Chaque URL invoque une servlet
•  Les servlets ont pour but de construire les objets JavaBeans chargés
de prendre en charge la logique métier
•  Ensuite, le contrôleur (la servlet) donne la main à la vue (la JSP) qui
devra se charger de construire la réponse HTML
•  Pour ce faire, la JSP utilisera les JavaBeans, par l'intermédiaire des
actions JSP
•  C'est la servlet qui connaît sa JSP associée
•  Une page JSP est une servlet
Exercice
•  Reprenez l’exemple précédent utilisant la classe
Personne
•  Créez une Servlet capable de se connecter à la
base de donnée afin de récupérer les données des
personnes et créer un groupe de personne (Ref. un
des exercices sur les servlets)
•  Faite les modifications nécessaires pour faire
fonctionner l’ensemble de façon que
–  La servlet réponde à la requête utilisateur
–  La servlet crée une liste de personnes
–  La page JSP affiche la liste.
8 Servlet and JSP Resources
•  JSP at Sun Microsystems
–  java.sun.com/products/jsp
•  Servlets at Sun Microsystems
–  java.sun.com/products/servlet
•  J2EE at Sun Microsystems
–  java.sun.com/j2ee
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