Introduction to JSP



Popular server side scripting language.
 Provides dynamic web contents.
 Make use of script lets and XML based tags.

JSP Page
Preprocessed

.java file (Servlet Code)
compiled

.class file
servlet



Ease of deployment.
 Support multithreading.
 Re-usable components.
 Support cross platform.



HTML
 Java scriptlets
 JSP directives
 JavaScript




Scripting- Insert java statements directly into the
program.
Directive- give direction to the JSP translator
 Two types are available, Include, Page, Taglib



Actions – Used to convert JSP elements to java
servlet codes. Tag Libraries provide additional action
elements.



Java statements are enclosed in special tags
<% ……. %>
<% =……. %>
<% !……. %>

Eg:

<% java.util.Date ct=new java,util.Date() %>
<%=%>

 A set of attributes which are applicable for the entire

jsp page.
 <%@ directive attr_name=value %>
 3 types of directives are defined over jsp
Page Directive
Include Directive
Tablib Directive

<html> <body> <P> The following is a JSP declaration<P>
<%! int x = 5;
private int aMethod(int y) {
return x * y;
}
%>
<P> The following is a JSP expression, notice the lack of semi-colon<P>
<P> This is a basic jsp<P>
<%= new java.util.Date() %>
<P> The following is a JSP scriptlet<P>
<UL>
<% for (int i = 0; i < 3; i++) {
%>
<LI><%= aMethod(i) %>
<% } %>
</UL></body></html>



Defines page-dependent attributes, such as scripting
language, error page, and buffering requirements



Syntax

<%@ page attribute="value"%>
or
<jsp:directive.page attribute="value" />// XML Markup

<%@ page
[ language=”Scripting Language” ]
[ extends=”ClassName” ]
[ import=”{package.class | package.*}, ...” ]
[ session=”true|false” ]
[ buffer=”none|8kb|sizekb” ]
[ autoFlush=”true|false” ]
[ isThreadSafe=”true|false” ]
[ info=”text” ]
[ errorPage=”relativeURL” ]
[ contentType=”mimeType [ ;charset=characterSet ]” |
“text/html ; charset=ISO-8859-1” ]
[ isErrorPage=”true|false” ]
%>

Attribute

Description

buffer

Specifies a buffering model for the output stream.

autoFlush

Controls the behavior of the servlet output buffer.

contentType

Defines the character encoding scheme.

errorPage

Defines the URL of another JSP that reports on runtime exceptions.

isErrorPage

if this JSP page is a URL specified by another JSP page's errorPage
attribute.

extends

Specifies a superclass that the generated servlet must extend

import

Specifies a list of packages or classes

info

Defines a string that can be accessed with the servlet's getServletInfo()

isThreadSafe Defines the threading model for the generated servlet.
language

Defines the programming language used in the JSP page.

session

Specifies whether or not the JSP page participates in HTTP sessions

isELIgnored Specifies whether or not EL expression within the page will be ignored.



Includes a file during the translation phase



Syntax

<%@ import file="relative url" %>
or
<jsp:directive.include file="relative url" /> // XML Markup



Declares a tag library, containing custom actions, used
in the page
 User defined tags to implement custom behaviour.


Syntax

<%@ taglib uri="uri" prefix="prefixOfTag" >
or
<jsp:directive.taglib uri="uri" prefix="prefixOfTag" />
// XML Markup



Core Tags
 Formatting tags
 SQL tags
 XML tags
 JSTL Functions

<%@ taglib prefix="c"
uri="http://java.sun.com/jsp/jstl/core" %>

Tag

Description

<c:out >

Like <%= ... >, but for expressions.

<c:set >

Sets the result of an expression evaluation in a 'scope'

<c:remove >

Removes a scoped variable (from a particular scope, if specified).

<c:catch>

Catches any Throwable that occurs in its body and optionally exposes it.

<c:if>

Simple conditional tag which evalutes its body if the supplied condition is
true.

<c:choose>

Simple conditional tag that establishes a context for mutually exclusive
conditional operations, marked by <when> and <otherwise>

<c:when>

Subtag of <choose> that includes its body if its condition evalutes to 'true'.

<c:otherwise >

Subtag of <choose> that follows <when> tags and runs only if all of the
prior conditions evaluated to 'false'.

<c:import>

Retrieves an absolute or relative URL and exposes its contents to either the
page, a String in 'var', or a Reader in 'varReader'.

<c:forEach >

The basic iteration tag, accepting many different collection types and
supporting subsetting and other functionality .

<c:forTokens>

Iterates over tokens, separated by the supplied delimeters.

<c:param>

Adds a parameter to a containing 'import' tag's URL.

<c:redirect >

Redirects to a new URL.



The JSTL formatting tags are used to format and
display text, the date, the time, and numbers for
internationalized Web sites.
 Syntax
<%@ taglib prefix="fmt“ uri= "http ://java. Sun .com /
jsp/jstl/fmt" %>

Tag

Description

<fmt:formatNumber>

To render numerical value with specific precision or format.

<fmt:parseNumber>

Parses the string representation of a number, currency, or
percentage.

<fmt:formatDate>

Formats a date and/or time using the supplied styles and pattern

<fmt:parseDate>

Parses the string representation of a date and/or time

<fmt:bundle>

Loads a resource bundle to be used by its tag body.

<fmt:setLocale>

Stores the given locale in the locale configuration variable.

<fmt:setBundle>

Loads a resource bundle and stores it in the named scoped
variable or the bundle configuration variable.

<fmt:timeZone>

Specifies the time zone for any time formatting or parsing
actions nested in its body.

<fmt:setTimeZone>

Stores the given time zone in the time zone configuration
variable

<fmt:message>

To display an internationalized message.





The JSTL SQL tag library provides tags for
interacting with relational databases (RDBMSs)
such as Oracle, mySQL, or Microsoft SQL Server.
Syntax
<%@ taglib prefix="sql"
uri="http://java.sun.com/jsp/jstl/sql" %>

Element

Description

<jsp:useBean>

Makes a JavaBeans component available in a page.

<jsp:getProperty>

Gets a property value from a JavaBeans component and adds
it to the response.

<jsp:s etProperty>

Sets a JavaBeans property value.

<jsp:include>

Includes the response from a servlet or JSP page during the
request processing phase.

<jsp:forward>

Forwards the processing of a request to a servlet or JSP page.

<jsp:param>

Adds a parameter value to a request handed off to another
servlet or JSP page using <jsp:include>or <jsp:forward>

<jsp:plugin>

Generates HTML that contains the appropriate client
browser-dependent elements (OBJECT or EMBED) needed
to execute an Applet with the Java Plugin software.

Tag

Description

<sql:setDataSource>

Creates a simple DataSource suitable only for prototyping

<sql:query>

Executes the SQL query defined in its body or through the sql
attribute.

<sql:update>

Executes the SQL update defined in its body or through the sql
attribute.

<sql:param>

Sets a parameter in an SQL statement to the specified value.

<sql:dateParam>

Sets a parameter in an SQL statement to the specified
java.util.Date value.

<sql:transaction >

Provides nested database action elements with a shared
Connection, set up to execute all statements as one transaction.



Are object which can use in JSP pages without
declaring them explicitly.

Object

Description

request

This is the HttpServletRequest object associated with the request.

response

This is the HttpServletResponse object associated with the response.

out

This is the PrintWriter object used to send output to the client.

session

This is the HttpSession object associated with the request.

application

This is the ServletContext object associated with application context.

config

This is the ServletConfig object associated with the page.

pageContext This encapsulates use of server-specific features like higher
performance JspWriters.
page

This is simply a synonym for this, and is used to call the methods defined by
the translated servlet class.

Exception

The Exception object allows the exception data to be accessed by designated
JSP.

Subclass - javax.servlet.ServletRequest
Methods are
REQUEST:

 getParameter()
 getParameterValues()
 getParameterNames()
RESPONSE: Subclass

- javax.servlet.ServletResponse

Subclass - javax.servlet.ServletResponse
Methods are:
 findAttribute
 getAttribute
 getAttributesScope
 getAttributesNamesInScope

Subclass - javax.servlet.http.HttpSession
Methods are:
 getId
 getValue
 getValueNames
 putValue

Subclass - javax.servlet.ServletContext
Scope of the object is within the application.
Methods are:
 getMimeType
 getRealPath

Subclass - javax.servlet.jsp. JspWriter
 Clear
 clearBuffer
 Flush
 getBufferSize
 getRemaining

Subclass - javax.servlet.ServletConfig
Methods are:
 getInitParameter
 getInitParameterNames

Subclass - java.lang.Object
Methods are:
 Authors does not use this object.

Subclass - java.lang.Throwable
Methods are:
 getMessage
 getLocalizedMessage
 printStackTrace

<@page isErrorPage=”true” %>
<HTML>
<HEAD>
<TITLE>Error</TITLE>
</HEAD>
</BODY>
The following error has occurred: <%= exception.toString() %>
</BODY>
</HTML>
Or
<%page errorPage=”/jspError.jsp” %>

<%@ page language="java" contentType="text/html" %>
<%! int globalCounter = 0; %>
<html>
<head>
<title>A page with a counter</title>
</head>
<body bgcolor="white">
This page has been visited: <%= ++globalCounter %> times.
<p>
<% int localCounter = 0;%>
This counter never increases its value: <%= ++localCounter %>
</body>
</html>

Can do by the following methods,
 JavaBean properties
 Request Information
 Looping over arrays

<html>
<jsp:useBean id="clock" class="java.util.Date" />
<% if (clock.getHours( ) < 12) { %>Good morning!<% }
else if (clock.getHours( ) < 17) { %>Good day!<% }
else { %>Good evening!<% } %>
</body>
</html>

<html>
<% if (request.getParameter(“id”)!=1) { %>Not a valid
member!
<% }
else if (request.getParameter(“id”)=2) { %>Welcome !<%
} else { %>Welcome Guest!<% } %>
</body>
</html>

<%@ page language="java" contentType="text/html" %><html>
<form action="loop.jsp">
<input type="checkbox" name="fruits" value="Apple">Apple<br>
<input type="checkbox" name="fruits" value="Banana">Banana<br>
<input type="checkbox" name="fruits" value="Orange">Orange<br>
<input type="submit" value="Enter">
</form>
<%
String[] picked = request.getParameterValues("fruits");
if (picked != null && picked.length != 0) {
%>
You picked the following fruits:
<ul>
<%
for (int i = 0; i < picked.length; i++)
{ out.println(picked[i]);
}
%></ul><% } %></body></html>

<% out.println();%> or <%=variable to be printed%>
<%@ page import="com.ora.jsp.util.*" %>
...
<tr>
<td>Name:</td>
<td><input type="text" name="userName"
value="<%= StringFormat.toHTMLString(userInfo.getUserName( )) %>" >
</td>
</tr>

Use of JavaBean components in JSP are,
 User input validation
 Inserting files
 Forwarding user data into pages
 Handling data base access

JavaBean components in JSP are,
 <jsp:useBean>
 <jsp:getProperty>
 <jsp:setProperty>
 <jsp:include>
 <jsp:forward>
 <jsp:plugin>

<jsp:useBean>
Syntax:
<jsp: useBean
id=”name” scope=” page| request| session| application”
class =”test” type=“” >
</jsp: useBean>

package chapter09.beans;
public class userInfo implements
java.io.Serializable {
private String last_name;
private String first_name;
private String phone;
private String email;
public userInfo() {}
public String getLastName()
{return last_name;}
public void setLastName(String
lastName)
{last_name = lastName;}
public String getFirstName()

{return first_name;}
public void setFirstName(String
firstName)
{first_name= firstName;}
public String getPhone()
{return phone;}
public void setPhone(String p)
{phone = p;}
public String getEmail()
{return email;}
public void setEmail(String e)
{email = e;
}
}

<%@ page import=”chapter09.beans.userInfo” %>
<%@ page import=”java.util.*” %>
<jsp:useBean id=”user” class=”userInfo” scope=”page” />
<HTML>
<HEAD>
</HEAD>
<BODY>
<B>Last Name:</BR><INPUT TYPE=”Text” NAME=”lname”
VALUE=”<%= user.getLastName() %>”
<B>First Name:</BR> INPUT TYPE=”Text” NAME=”fname”
VALUE=”<%= user.getFirstName() %>”
”><B>Phone:</BR></TD>
<TD><INPUT TYPE=”Text” NAME=”phone” VALUE=”<%=
user.getPhone() %>”
INPUT TYPE=”Text” NAME=”email” VALUE=”<%= user.getEmail()
%>”
</BODY></HTML>

By two different ways,
Passing control between pages
Passing data between pages
a. Passing control between pages
By using <jsp:forward>
Attributes are,
page

Example : “test.jsp”

name

“name”

value

“give any value”

<jsp:forward page="userinfoinput.jsp" >
<jsp:param name="msg" value="Invalid email address" />
</jsp:forward>

Introduction to JSP

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