J2EE_Part1 By Saurabh

7/26/2019 J2EE_Part1 By Saurabh

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J2EE 5: Web Component DevelopmentJ2EE 5: Web Component Development

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Introductions

Your name

Location [home, office]

Job role

How long with[industr, !ractice area, communit]

"omething uni#ue about ourself

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Course objectives

$!on com!leting this course, ou should be able to%

&ro'ide an o'er'iew of the J(EE

)uild a "er'let

Discuss the basic conce!ts of H**&

Discuss "er'let +&

Discuss the "er'let life ccle

Discuss E-ce!tions and Errors

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Day 1 coverage

Ja'a "er'let *echnolog

odule /% J(EE O'er'iew

odule (% )uilding a "er'let

odule 0% H**& )asics

odule 1% "er'let +&

odule 2% "er'let Life 3cle

odule 4% "er'let Ob5ects

odule 6% E-ce!tions and Errors

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Houseeeping

)rea7s

8ashrooms

9o !agers or cell !hones

&artici!ation

:uestions

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!odule 1: J2EE overvie"

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+fter com!leting this module, ou should be able to e-!lain%

)asic conce!ts of J(EE

E'olution of Enter!rise +!!lication Framewor7

Enter!rise a!!lications O!en and "tandard solution

&latform ;alue

J(EE /.1 and JEE 2 +&s and technologies

3ontainers and 3om!onents J(EE De'elo!ment roles

De!loment Descri!tor

+!!lication ser'er !roducts

!odule objectives

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#asic concepts

W$at is t$e J2EE%

+n o!en and standard based !latform for de'elo!ing, de!loing, and

managing n3*"?

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Evolution o& Enterprise 'pplication (rame"or

"ingle tier

*wo tier

*hree tier

@&3 based

= @emote ob5ect based

= *hree tier >H*L browser and 8eb ser'er?

&ro!rietar a!!lication ser'er

"tandard a!!lication ser'er

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Enterprise applications

*hings that ma7e u! an enter!rise a!!lication

= &resentation logic

= )usiness logic

= Data access logic >and data model?

= "stem ser'ices

*he e'olution of enter!rise a!!lication framewor7 reflects

= How fle-ibl ou want to ma7e changes

= 8here the sstem ser'ices are coming from

To SME:

Is there a need to provide a brief description of each Enterprise app element?

To SME:

Is there a need to provide a brief description of each Enterprise app element?

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)pen and standard solution

$se Acom!onent and containerA model in which container !ro'ides sstem

ser'ices in a well


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*lat&orm value

*lat&orm value to Developers

3an use an J(EE im!lementation for de'elo!ment and de!loment

$se !roduction


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*lat&orm value +continued,

*lat&orm value to -endors

;endors wor7 together on s!ecifications and then com!ete in im!lementations

in the areas of scalabilit, !erformance, reliabilit, a'ailabilit, management and

de'elo!ment tools, and so on

Freedom to inno'ate while maintaining the !ortabilit of a!!lications

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*lat&orm value +continued,

*lat&orm value to #usiness Customers

+!!lication !ortabilit

an im!lementation choices are !ossible based on 'arious re#uirements

&rice >free to highsingle 3&$ to clustered model?, reliabilit,!erformance, tools, and more

)est of breed of a!!lications and !latforms

Large de'elo!er !ool

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JEE 5 '*Is and tec$nologies

J+B


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Containers and components

3ontainers do their wor7 in'isibl

9o com!licated +&s

3ontainers im!lement J(EE

Loo7 the same to com!onents

;endors ma7ing the containers ha'e great freedom to inno'ate

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J2EE development roles

3om!onent !ro'ider

)ean !ro'ider

+!!lication assembler

De!loer &latform !ro'ider

3ontainer !ro'ider

*ools !ro'ider

"stem administrator

To SME:

Is there a need to provide a brief description of each role in the instructor notes?

To SME:

Is there a need to provide a brief description of each role in the instructor notes?

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0$e application component provider

= is t$e company or person "$o creates Web components enterprise beans applets orapplication clients &or use in J2EE applications

+n enter!rise bean !ro'ide%

= 8rites and com!iles the source code

= creates the de!loment descri!tor or uses annotations

= )undles the .class files and de!loment descri!tor into an EJ) J+@ file

*he a!!lication assembler

= is the !erson or !eo!le who recei'es a!!lication com!onent J+@ files from com!onent!ro'iders and assembles them into a J(EE a!!lication E+@ file.

De!loer and +dministrator

= *he a!!lication de!loer and administrator is the !erson who configures and de!los the J(EEa!!lication, administers the com!uting and networ7ing infrastructure where J(EE a!!licationsrun, and o'ersees the runtime en'ironment. Duties include such things as setting transactioncontrols and securit attributes and s!ecifing connections to databases.

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&latform &ro'ider

= O!erating "stem ;endor 'iG>8indows8eb"!here = ), 8ebLogic = )E+, etc? *ool &ro'ider

= ntegrated De'elo!ment Editor>DE? !ro'ider >@+D =), 9et)eans< O!en "ource?

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Deployment descriptor

i'es the container instructions on how to manage and control beha'iors of

the J(EE com!onents

*ransaction

"ecurit

&ersistence

+llows declarati'e customiGation >as o!!osed to !rogramming customiGation?

BL file

Enables !ortabilit of code

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'pplication server

+n application serveris a software engine that deli'ers a!!lications to client

com!uters or de'ices. oreo'er, an a!!lication ser'er handles most, if not all,

of the business logic and data access of the a!!lication

Features%

= +!!lication ser'er !roducts t!icall bundle middle"areto enable a!!lications to

intercommunicate with de!endent a!!lications, li7e 8eb ser'ers, database

management sstems and chart !rograms.

= &ortals are a common a!!lication ser'er mechanism b which a single !oint of entr

is !ro'ided to multi!le de'ices.

= EJ) are hosted in an +!!lication "er'er. "ome common e-am!le of +!!lication"er'er are 8eb"!here +!!lication "er'er >)?, J)oss >@edHat?, *omcat >+!ache?,

"un+!!"er'er> "un icrosstems?, 8ebLogic "er'er >)E+?.

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'ny uestions%

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!odule 2: #uilding a 3ervlet

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+fter com!leting this module, ou should be able to%

Define a 8eb com!onent

Define a "er'let

Enumerate the benefits using a "er'let Enumerate the ad'antages of using a "er'let o'er

3

Enumerate the features of a "er'let

E-!lain how a "er'let is built

!odule objectives

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W$at is a Web Component%

+ web com!onent is a software entit that runs on a web ser'er, !ro'iding it with

the ca!abilities needed for dnamicall handling client re#uests and generating

web !resentation content.

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W$at is a 3ervlet%

"er'er side Ja'a !rogram that e-tends the functionalit of a 8eb "er'er

$sed to dnamicall generate H*L documents

3om!arable to%

= 3= 9etsca!e 9"+&

= icrosoft "+&

= +!ache odules

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3ervlet bene&its

8ritten in !ure Ja'a

= &latform inde!endent

= 3an ta7e ad'antage of JD)3, EJ), J", Ja'aail, Ja'aDL, @, and more

"er'er inde!endent

"calabilit

= DoesnIt start new !rocess for each re#uest

= 3an run in same ser'er !rocess as H**& ser'er

= ulti


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3ervlet advantage over C4I

+ "er'let does not run in a se!erate !rocess

+ "er'let stas in memor between re#uests

*here is onl a single instance which answers all re#uests concurrentl

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#uilding a 3ervlet using t$e 3ervlet '*I

E-tend Htt!"er'let

3ode "er'letIs life ccle ethods

GenericServletGenericServlet

ServletServlet

HttpServletHttpServlet

LogonServletLogonServlet

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sage o& 3ervlet

&rocessing or storing data submitted b an H*L form

&ro'iding dnamic content

anaging state information

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(eatures o& 3ervlet

3ecurity

nherits the securit feature !ro'ided b the container

3ession !anagement

aintains the identit and state of an end user across multi!le re#uests

Instance *ersistence

Enhances the !erformance of the ser'er b !re'enting fre#uent dis7 access

*lat&orm and server independent

+'ailable and running on all ma5or web ser'ers and a!!lication ser'ers

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http://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/GenericServlet.htmlhttp://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/http/HttpServlet.htmlhttp://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/http/HttpServlet.htmlhttp://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/Servlet.htmlhttp://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/Servlet.htmlhttp://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/GenericServlet.htmlhttp://../PRP_Material/j2sdkee-beta/doc/api/javax/servlet/GenericServlet.html


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#uilding a 3ervlet

J2EE 'pplication 3erver

Web Container

Web Client

+#ro"ser,

Web Client

+#ro"ser, 3ervlet

@e#uest

@es!onse

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J2EE 'pplication 3erver

Web Container

#uilding a 3ervlet +continued,

Loads *he "er'let classLoads *he "er'let class

nstantiates the "er'letnstantiates the "er'let

nitialiGes the "er'let nstancenitialiGes the "er'let nstance

&asses re#uest to the "er'letnstance

&asses re#uest to the "er'letnstance

"ends @es!onse"ends @es!onse

First 3lient

@e#uest

First 3lient

@e#uest

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'ny uestions%

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!odule 6: H00* #asics

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Define or describe H**&

E-!lain a H**& @e#uest

E-!lain a H**& @es!onse

!odule objectives

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Introduction

*he H!erte-t *ransfer &rotocol >H**&? is an a!!lication


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H00* 8euest

+n H**& re#uest has three !arts%

= + re#uest line

= One or more re#uest headers

= + message

+ re#uest line loo7s li7e%

GET /WelcomeProect/!ome"html !TTP/#"#

1sttoken is the name of the method, in this case it is GET

2ndtoken is the URL, that gives information about the location of the

resource to be gotten.

The last token is the version of HTT to be used.

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H00* 8esponse

+n H**& res!onse similarl has three !arts%

= + res!onse line

= One or more res!onse headers

= + message

+ res!onse line loo7s li7e%

!TTP/#"# $%% &'

1sttoken is the HTT version.

2ndtoken is one of the man!predefinedstatus codes.

"rd token is an English descri#tion of the status code.

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'ny uestions%

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!odule /: 3ervlet '*I

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E-!lain how a "er'let is created

E-!lain how a "er'let is !ac7aged

Discuss the $eb.%ml

!odule objectives

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3ervlet creation

"te!s to create standard !ac7aging structure of a web a!!lication, create the

following directories%

+ root director

t contains the static resources, such as, H0!9, J3*and imagefiles.

+ 8E)


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3ervlet pacaging

J(EE defines a standard !ac7aging structure to !ac7age a ser'let into a J(EE

a!!lication to ma7e it !ortable across different a!!lication ser'ers.

+ standard !ac7aging structure will allow a!!lication ser'ers to easil locate

and load a!!lication files from the standard director structure.

n most of the cases, the standard !ac7aging structure is created b thentegrated De'elo!ment En'ironment in use li7e, R&', (!Ecli#se, )*&',

*un#*erver.

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Directory structure o& a Web 'pplication

@oot Director@oot Director

8E)


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Deployment Descriptor: "eb.ml

0$e "eb.ml consists o&:

BL &rolog information

8eb +!!lication dis!la name

"er'let information such as%= "er'let Dis!la 9ame

= 9ame of the "er'let, when it will be accessed

= "er'let 3lass 9ame

= $@L a!!ings

= 8elcome files

= E t!es

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Content o& "eb.ml:

+%ml version-1./0 encoding-UT30 4+$eba## version-2.50 %mlns-htt#6778ava.sun.com7%ml7ns782ee0%mlns6%si-htt#677$$$.$".org72//179(L*chema:nstance%si6schemaLocation-htt#6778ava.sun.com7%ml7ns782ee htt#6778ava.sun.com7%ml7ns782ee7$eba##;2;5.%sd04

+dis#la!name4)elcome#lication+7dis#la!name4+servlet4

+dis#la!name4)elcome*ervlet+7dis#la!name4+servletname4)elcome*ervlet+7servletname4+servletclass4ibm.sam#le.)elcome*ervlet+7servletclass4+7servlet4+$elcomefilelist4+$elcomefile4)elcome*ervlet+7$elcomefile4+7$elcomefilelist4

+servletma##ing4+servletname4)elcome*ervlet+7servletname4+url#attern47)elcome*ervlet+7url#attern4+7servletma##ing4+7$eba##4

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1. Creating a H0!9 *age: serIn&o.$tml

+html4

+title4:nformation age+7title4

+bod!4

+h14User :nformation age+7h14

+hr color-e-?4

+form action-*http://localhost:+%,%/Welcome-ser.pplication/Welcome-ser4+#re4

Enter @our irst Aame 6 +in#ut t!#e-te%t0 name-fname04

Enter @our Last Aame 6 +in#ut t!#e-te%t0 name-lname04

+in#ut t!#e-submit0 value-*ubmit04 +in#ut t!#e-reset0 value-Blear04

+7form4

+7#re4+7bod!4

+7html4

8eb3onte-t @oot8eb3onte-t @oot

"er'let +lias 9ame"er'let +lias 9ame

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#ackage ibm.sam#leC

im#ort 8ava.io.DC

im#ort 8ava%.servlet.DC

im#ort 8ava%.servlet.htt#.DC

#ublic class )elcomeUser e%tends Htt#*ervlet

#ublic void doGetFHtt#*ervletReuest reuest, Htt#*ervletRes#onse res#onse

thro$s :IE9ce#tion, *ervletE%ce#tion

*tring firstname - request"0etParameter1*fname23

res#onse.setBontentT!#eFte%t7html0C

rint)riter out - res#onse.get)riterFC

out.#rintlnF+h14)elcome J +font color-


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6. 3ave and deploy t$e 3ervlet

3lic7 on "a'e button in the @+D DE, if it dis!la some red cross mars in

your code t$encorrect it and then sa'e to generate a .class file.

De!lo the web module containing Welcomeser"er'let. @ight clic7 on the

Welcomeser.javaand select @un


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/. 'ccess t$e H0!9 page in t$e Web #ro"ser

htt!%localhost%KCC8elcome$ser+!!lication$sernfo.html

O!en the web browser *!e the $@L here &ress EnterM 7e

O!en the web browser *!e the $@L here &ress EnterM 7e

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/. 'ccess t$e H0!9 page in t$e Web #ro"ser +continued,

htt!%localhost%KCC8elcome$ser+!!lication8elcome$serNfname)lnamendia

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'ny uestions%

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!odule 5: 3ervlet li&e cycle

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Discuss the lifeccle of a "er'let

Discuss the initFmethod

Discuss the serviceF method

Discuss the destro!Fmethod

!odule objectives

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9i&ecycle o& a 3ervlet

Servlet

init( )doGet( )

HTTP

Serv

er

HTTP

Serv

er

Servlets Container

destroy( )

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9i&ecycle o& a 3ervlet +continued,

Servlet

init( )doGet( )

Servlets Container

destroy( )

Thread

Thread

Thread

HTTP

Serv

er

HTTP

Serv

er

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0$e init12met$od

#ublic void initF*ervletBonfig thro$s *ervletE%ce#tion

*his method is for the initialiGation of the ser'let.

One can establish database connection in this method which could be sharedb e'er client.

*his method is called onl once during the life of a ser'let.

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0$e service12met$od

#ublic void Service(ServletRequest, ServletResponse)thro$s

*ervletE%ce#tion, :IE%ce#tion

*his method is called once !er client.

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0$e destro412met$od

#ublic void destroy()

3alled to destro the ser'let and release the resources

$suall called b the "er'let 3ontainer

3alled once during the life of a ser'let

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9i&ecycle o& a 3ervlet +continued,

;ote:

De!ending on how ou register our

ser'let with the web ser'er, it can be

created either when a client first

references a $@L that corres!onds tothe ser'let, or when the web ser'er is

first started.

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'ny uestions%

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!odule


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+fter com!leting this module, ou should be able to discuss%

"er'let 3onte-t

"co!e of "er'let ob5ects

"er'let nterface methods "ession anagement

$sing the H**& "ession nterface

!odule objectives

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3ervlet object

Enables sharing information among collaborating web com!onents 'ia

attributes maintained in sco!e ob5ects.

= +ttributes are name ob5ect !airs.

+ttributes maintained in the "co!e ob5ects are accessed with

= get+ttribute>? and set+ttribute>? method

"co!e ob5ects )elongs to

8eb3onte-t >"er'let3onte-t? 8ava%.servlet.*ervletBonte%t

"ession 8ava%.servlet.htt#.Htt#*ession

@e#uest 8ava%.servlet.*ervletReuest

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3ervlet Contet

t is shared b all ser'lets and J"& !ages within a "eb applicationM.

*here is one "er'let3onte-t ob5ect !er web a!!licationM !er J;.

"et and get conte-ta!!lication


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3cope o& 3ervlet objects

'pplication

"er'let3onte-t

3lient /

3lient (

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3ervlet Inter&ace met$ods

3ervlet Inter&ace !et$ods

!et$od ;ame Description

!ublic "er'let3onfigget"er'let3onfig>?

@eturns a "er'let3onfig ob5ect thatcontains configuration information, suchas initialiGation !arameters, to initialiGe aser'let.

!ublic "tring get"er'letnfo>?t returns a string that containsinformation about the ser'let, such asauthor, 'ersion, and co!right.

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3ervlet Contet met$ods +continued,

3ervlet Contet !et$ods


!ublic 'oid set+ttribute>"tring s,Ob5ect ob5?

)inds the ob5ect with a name and storesthe name'alue !air as an attribute of the"er'let3onte-t ob5ect.

!ublic Ob5ect get+ttribute>"tringattribute9ame?

@eturns the ob5ect stored in the"er'let3onte-t ob5ect with name !assedas a !arameter.

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3cope o& 3ervlet objects +continued,

Ho" to get t$e 3ervletcontet )bject:

*ervletBonte%t conte%t - 0etServlet5onfi012"0etServlet5onte)t123

IR

*ervletBonte%t conte%tC#ublic void initF*ervletBonfig cfg

conte%t - cf0"0etServlet5onte)t123

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3ession !anagement

3o $o" toimplement it=

3o $o" toimplement it=

echanism to maintain client state across a series of re#uests from a same user

or originating from the browser o'er some !eriod of time.

E-am!le% Online "ho!!ing 3art.

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Implementation

Login"creen

Dis!la*rouserList"er'let

3hoice&rocessing"er'let

Final"er'let

+cce!t $ser9ame and &assword and on submissioncall Display0rouser9ist3ervlet .

*his ser'let dis!las the list of trouser a'ailable in thestoc7 and on submission call a "er'let 7nown asC$oice*rocessing3ervletfor further !rocessing.

*his ser'let 7ee! trac7 of the user selection of thetrouser and forward the selected trouser list to the(inal3ervletfor )illing the user.

*his ser'let calculate the total bill for the user based onthe *rouser selected >*rouser selection informationretrie'ed from C$oice*rocessing3ervlet?

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9ogin *age ? 9ogin.$tml

PH*L

P**LEHa!!;isit Online "ho!!ing &ortalP**LE

P)ODY

PFO@ +3*O9 @$ttp:AAlocal$ost:BA3ession3ervlet*rojectADisplay0rouser9ist3ervlet@align3E9*E@M

$sername% P9&$* *Y&E *EB* 9+E AuserA align3E9*E@P)@&assword% P9&$* *Y&E &+""8O@D 9+E A!asswordA align3E9*E@P)@

P9&$* *Y&E "$)* ;+L$E ALoginA align3E9*E@

PFO@

P)ODY

PH*L

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3ervlet 71: Display0rouser9ist3ervlet.java

!ac7age ibm.sam!le.loginQ

im!ort 5a'a.io.RQ

im!ort 5a'a-.ser'let.RQ

im!ort 5a'a-.ser'let.htt!.RQ

!ublic class Display0rouser9ist3ervlete-tends Http3ervlet

S

!ublic 'oid do4et>Htt!"er'let@e#uest re#, Htt!"er'let@es!onse res? throws "er'letE-ce!tion, OE-ce!tion

S

"tring username re#.get&arameter>AuserA?Q

"tring !assword re#.get&arameter>A!asswordA?Q

int counter CQ

&rint8riter out res.get8riter>?Q

out.!rintln> username T AU 8elcome to Ha!!;isit Online "ho!!ing.P)@A?Q

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counter CQ

R 3reate a session for the user and store the 'alue of username. R

Htt!"ession session re#.get"ession>true?Q

session.set+ttribute>AuserA, username?Q

V

else

S

out.!rintln>A"orrU n'alid username and !asswordA?Q

counter /Q

V

if >counter C?

S

R Dis!la the contents to the user. R

out.!rintln>APH*LP)ODYA?Q

out.!rintln>APH@A?Q

out.!rintln>APFO@ +3*O9 $ttp:AAlocal$ost:BA3ession3ervlet*rojectAC$oice*rocessing3ervlet !E0H)D*)30A?Q


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out.!rintln>AP*+)LE 8D*H2CCA?Qout.!rintln>AP*@P*H*E 9OP*H P*H)rands of *rousers P*H P*H)$YP*H P*@ A?Q

out.!rintln>AP*@P*D / P*DP*D &eterEngland P*D P*D P9&$* 9+E c/ *Y&E 3HE3W)OB ;+L$E &eterEngland P*D P*@ A?Q

out.!rintln>AP*@P*D ( P*DP*D oustache P*D P*D P9&$* 9+E c( *Y&E 3HE3W)OB ;+L$E oustache P*D P*@ A?Q

out.!rintln>AP*@P*D 0 P*DP*D +llen "oll P*D P*D P9&$* 9+E c0 *Y&E 3HE3W)OB;+L$E +llen "ollP*D P*@ A?Q

out.!rintln>AP*@P*D 1 P*DP*D Xodiac P*D P*D P9&$* 9+E c1 *Y&E 3HE3W)OB;+L$E XodiacP*D P*@ A?Q

out.!rintln>AP*+)LEA?Q

out.!rintln>AP9&$* *Y&E "$)* ;+L$E "$)*A?Qout.!rintln>APFO@A?Q

out.!rintln>AP)ODYPH*LA?Q out.close>?Q

V

V

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im!ort 5a'a.io.RQ



im!ort 5a'a.util.RQ

!ublic class C$oice*rocessing3ervlet e-tends Http3ervlet

S

!ublic 'oid do*ost+Htt!"er'let@e#uest re#uest, Htt!"er'let@es!onse res!onse? throws "er'letE-ce!tion, OE-ce!tion

S

"tring user null Q

"tring item nullQ

int i /Q

Enumeration enum nullQ

&rint8riter out res!onse.get8riter>?Q

Htt!"ession session re#uest.get"ession>true?Q

3ervlet 7 2: C$oice*rocessing3ervlet.java

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user >"tring?session.get+ttribute>AuserA?Q

R @etrie'e the name of all the !arameters !assed b the end user. R

enum reuest.get*arameter;ames+,F

while >enum.hasoreElements>??

S

"tring sname >"tring?enum.ne-tElement>?Q

R "tore the names in the session ob5ect. R

session.set'ttribute +@c@Gi sname,F

iTTQ

V

R "tore the counter 'alue in the session ob5ect. R

session.set'ttribute+@counter@ i G@@,F

@e#uestDis!atcher dis! re#uest.get@e#uestDis!atcher>A(inal3ervletA?Q

disp.&or"ard+reuest response,F

V

V

3ervlet 7 2: C$oice*rocessing3ervlet.java

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im!ort 5a'a.io.RQ



!ublic class (inal3ervlete-tends Http3ervlet

S

!ublic 'oid do*ost>Htt!"er'let@e#uest re#uest, Htt!"er'let@es!onse res!onse? throws "er'letE-ce!tion, OE-ce!tion

S

"tring trcode/ nullQ

"tring trcode( nullQ

"tring trcode0 nullQ

"tring trcode1 nullQ

int !rice/ CQ

int !rice( CQ

int !rice0 CQ

int !rice1 CQ

int total&rice CQ

"tring username AAQ

3ervlet 7 6: (inal3ervlet.java



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&rint8riter out res!onse.get8riter>?Q

Htt!"ession session re#uest.get"ession>true?Q

R @etrie'e the 'alue bound to AuserA. R

username >"tring?session.get+ttribute>AuserA?Q

R @etrie'e the 'alue bound to AcounterA.R

"tring counter >"tring?session.get+ttribute>AcounterA?Q

int count nteger.!arsent>counter?Q

for>int i/Q iPcountAcATi?Q




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R 3alculate the total !rice of selected items.R

if >>trname[iAc/A??

S

!rice/ 112Q

V

if >>trname[iAc(A??

S

!rice( 42CQ

V

if >>trname[iAc0A??

S

!rice0 242Q

Vif >>trname[iAc1A??

S

!rice1 /(62Q

V

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R 3alculate the total bill. R

total&rice !rice/ T !rice( T !rice0 T !rice1Q

R Dis!la the total bill that the user has to !a. R

out.!rintln>username T , our bill is @s A T total@ate?Q

out.!rintln>AP)ODYPH*LA?Q

out.close>?Q

V

V




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Http3ession

Http3ession !et$ods


!ublic 5a'a.lang.Ob5ect

get'ttribute>5a'a.lang."tring name?

!ublic 'oid set'ttribute>5a'a.lang."tring name,

5a'a.lang.Ob5ect 'alue?

!ublic 'oidremove'ttribute>5a'a.lang."tring name?

!ublic 'oid invalidate>?

!ublic 'oidset!aInactiveInterval>int inter'al?

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'ny uestions%

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!odule >: Eceptions and errors

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+fter com!leting this module, ou should be able to e-!lain%

"er'letE-ce!tion

$na'ailableE-ce!tion

How to send error message to 3lient

Logging errors in "er'lets

!odule objectives

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Eceptions and Errors in 3ervlets

+ 3ervletEceptionindicates

that a general e-ce!tion has

occurred.

E-ce!tion

>from 5a'a.lang?

3ervletEception

+&rom java.servlet,

$na'ailableE-ce!tion>from 5a'a-.ser'let?

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Eceptions and Errors in 3ervlets +continued,

+n navailableEception is

thrown when a !articular ser'let

is tem!oraril or !ermanentl

una'ailable cannot handle

re#uests, such as if a ser'let is

incorrectl configured, or aresource it de!ends on is

una'ailable.

E-ce!tion

>from 5a'a.lang?

3ervletEception

+&rom java.servlet,

$na'ailableE-ce!tion>from 5a'a-.ser'let?

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3end error message to Client

#ublic void sendErrorFint status;code

O@

#ublic void sendErrorFint status;code, *tring message

)oth the methods belong tojava.servlet.$ttp.Http3ervlet8esponse

Inter&ace

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9ogging errors

"er'lets ha'e the abilit to write their actions and their errors to a log file using

the log>? method%

*he log>? method aids debugging b !ro'iding a wa to trac7 a ser'letIs

actions.

t also offers a wa to sa'e a com!lete descri!tion of an errors encounteredb the ser'let.

*he descri!tion can be the same as the one gi'en to the client, or it can be

more e-hausti'e and detailed.

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9ogging errors +continued,

*he eneric"er'let class !ro'ides a log>? method%

#ublic void Generic*ervlet.logF*tring msg6

logFmsgC

get*ervletBonte%tF.logFe, msgC

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'ny uestions%

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3ession eercise

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Eercise

8rite a "er'let which will read the database details 'iG. dri'er details and 5dbc

url from the "er'let3onfig and establish a database connection.

8rite a ser'let that will search a Em!loee based on his or her Em!loee D. f

an em!loee e-ists with that D, it dis!las the details of that em!loee.

Otherwise shows no em!loee record e-ist with that name.

3onsider the following em!>table?

Em#

= Em#no FM

= Ename

= *al

= Hiredate

= de#tno FM

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3ession summary

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3ummary

+lthough some client re#uests might onl re#uire !rebuilt !ages, there are

certain situations in which web !ages need to be built dnamicall.

"er'let technolog !ro'ides ser'er


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3ummary +continued,

*he ser'let +& consists of two !ac7ages =java.servletand

java.servlet.$ttp= which !ro'ide all the interfaces and classes needed for

coding ser'lets.

+ll the ser'lets must im!lement "er'let interface either directl or indirectl.

*he eneric "er'let class is used to code generic, !rotocol


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3ummary +continued,

*he ser'let life ccle is controlled b the web container using a number of

methods, including init service do and destroy.

*here are two e-ce!tion classes associated with Ja'a ser'lets.

3ervletEception indicates that a general e-ce!tion has occurred, and

navailableEceptionindicates that the ser'let is not a'ailable to handle

re#uests.

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8e&erences

htt!%www.wd'l.comnternet&rotocolsH**&

htt!%roseindia.net

htt!%www.min#.se!roducts!uretestdochtmlcommonwebtestwebtest0.html

Date post:	01-Mar-2018
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J2EE_Part1 By Saurabh

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