Web Programming Unit5 2 & 16 Marks

1
Mailam Engineering College
(Approved AICTE, New Delhi Affiliated to Anna University Chennai
& Accredited by National of Accreditation (NBA New Delhi
Mailam Villupuram (Dt), Pin – 604 304
DEPARTMENT ! CMP"TER APP#$CAT$N%
%u&'e(t Name ) *e& Programming
%u&'e(t Co+e ) MC,-3.
/ear ) -00- – -003
%eme1ter ) $$$
Prepare+ 23 ) M14A4%u&at5ra De6i
%u&'e(t $n(5arge 7D Prin(ipal
Prepared by
Ms.A.Subathra Devi
2
*e& Programming
UNIT V ADVANCED JAVA PROGRAMMING
Utility Packages – Input Output Packages – Inner Classes – Java Database Connectivity -
Servlets - RMI – Java Beans
- – Mar81 9ue1tion1 :it5 An1:er1
04 *53 +o t5rea+1 &lo(8 on $;<
Threads bloc! on I"# that other threads $ay e%ec&te while the I"# #peration is
perfor$ed
-4 *5at i1 t5e Ve(tor (la11<
The 'ector class provides the capability to i$ple$ent a (rowable array of ob)ects
34 *5at mo+i=ier1 ma3 &e u1e+ :it5 an inner (la11 t5at i1 a mem&er o= an outer
(la11<
A (non*local inner class $ay be declared as p&blic, protected, private, static, final, or
abstract+
44 Doe1 gar&age (olle(tion guarantee t5at a program :ill not run out o= memor3<
,arba(e collection does not (&arantee that a pro(ra$ will not r&n o&t of $e$ory+ It is
possible for pro(ra$s to &se &p $e$ory reso&rces faster than they are (arba(e collected+
It is also possible for pro(ra$s to create ob)ects that are not s&b)ect to (arba(e collection+
.4 Name t5ree Component 1u&(la11e1 t5at 1upport painting4
The Canvas, -ra$e, .anel, and Applet classes s&pport paintin(+
64 *5at an $; =ilter<
An I"# filter is an ob)ect that reads fro$ one strea$ and writes to another, &s&ally
alterin( the data in so$e way as it is passed fro$ one strea$ to another+
>4 *5at i1 ?a6a %er6let<
A servlet is a /ava technolo(y*based 0eb co$ponent, $ana(ed by a container called
servlet container or servlet en(ine, that (enerates dyna$ic content and interacts with web
clients via a re1&est"response paradi($+
@4 *5atA1 t5e +i==eren(e &et:een 1er6let1 an+ applet1<
2ervlets are to servers, applets are to browsers+ Unli!e applets, however, servlets
have no (raphical &ser interface+
,4 *5atA1 t5e a+6antage1 u1ing 1er6let1 t5an u1ing CB$<
2ervlets provide a way to (enerate dyna$ic doc&$ents that is both easier to write
and faster to r&n+ It is efficient, convenient, powerf&l, portable, sec&re and ine%pensive+
2ervlets also address the proble$ of doin( server*side pro(ra$$in( with platfor$*specific
A.Is3 they are developed with /ava 2ervlet A.I, a standard /ava e%tension+

004 *5at are t5e purpo1e o= %er6let1< "9 CNo6;De( -000D
A servlet can handle $&ltiple re1&ests conc&rrently, and can synchroni4e re1&ests+
This allows servlets to s&pport syste$s s&ch as on*line conferencin(+ 2ervlets can forward
re1&ests to other servers and servlets+ Th&s servlets can be &sed to balance load a$on(
several servers that $irror the sa$e content, and to partition a sin(le lo(ical service over
several servers, accordin( to tas! type or or(ani4ational bo&ndaries+

Prepared by
Ms.A.Subathra Devi
3
004 *5atA1 t5e %er6let $nter=a(e<
The central abstraction in the 2ervlet A.I is the 2ervlet interface+ All servlets
i$ple$ent this interface, either directly or, $ore co$$only, by e%tendin( a class that
i$ple$ents it s&ch as 5ttp2ervlet+ 2ervlets67,eneric 2ervlet675ttp2ervlet678y2ervlet+
The 2ervlet interface declares, b&t does not i$ple$ent, $ethods that $ana(e the servlet
and its co$$&nications with clients+ 2ervlet writers provide so$e or all of these $ethods
when developin( a servlet+
0-4 *5en a 1er6let a((ept1 a (all =rom a (lient, it re(ei6e1 t:o o&'e(t14 *5at are
t5e3<
2ervelt9e1&est3 which encaps&lates the co$$&nication fro$ the client to the server+
2ervlet9esponse3 which encaps&lates the co$$&nication fro$ the servlet bac! to the client+
2ervlet9e1&est and 2ervlet9esponse are interfaces defined by the )ava%+servlet pac!a(e+
034 De=ine 1er6let #i=e C3(le4 C"9 No6;De(
-00,D
A servlet life cycle can be defined as the entire process fro$ its creation till the
destr&ction+ The followin( are the paths followed by a servlet
• The servlet is initiali4ed by callin( the init () $ethod+
• The servlet calls 1er6i(e() $ethod to process a client:s re1&est+
• The servlet is ter$inated by callin( the +e1tro3() $ethod+
• -inally, servlet is (arba(e collected by the (arba(e collector of the /'8+
044 *5en a (lient reEue1t i1 1ent to t5e 1er6let (ontainer, 5o: +oe1 t5e (ontainer
(5oo1e :5i(5 1er6let to in6o8e<
The servlet container deter$ines which servlet to invo!e based on the confi(&ration
of its servlets, and calls it with ob)ects representin( the re1&est and response+
0.4 De=ine %er6let $= a 1er6let i1 not properl3 initialiFe+, :5at eG(eption ma3 &e
t5ro:n<
D&rin( initiali4ation or service of a re1&est, the servlet instance can throw an
UnavailableE%ception or a 2ervletE%ception+
064 *5at i1 =ilter< Can =ilter &e u1e+ a1 reEue1t or re1pon1e<
A filter is a re&sable piece of code that can transfor$ the content of 5TT.
re1&ests,responses, and header infor$ation+ -ilters do not (enerally create a response or
respond to a re1&est as servlets do, rather they $odify or adapt the re1&ests for a
reso&rce, and $odify or adapt responses fro$ a reso&rce+
0>4 *5at i1 ne: in %er6letReEue1t inter=a(e<
The followin( $ethods have been added to 2ervlet9e1&est ;+< version3
p&blic int (et9e$ote.ort(
p&blic )ava+lan(+2trin( (et=ocalNa$e(
p&blic )ava+lan(+2trin( (et=ocalAddr(
p&blic int (et=ocal.ort(
0@4 7o: (an $ 1en+ u1er aut5enti(ation in=ormation :5ile ma8ing"R#Conne(tion<
>o&:ll want to &se 5ttpU9=Connection+set9e1&est.roperty and set all the appropriate
headers to 5TT. a&thori4ation+
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0,4 Can :e u1e t5e (on1tru(tor, in1tea+ o= init(), to initialiFe 1er6let<
>es , of co&rse yo& can &se the constr&ctor instead of init(+ There:s nothin( to stop
yo&+ B&t yo& sho&ldn:t+ The ori(inal reason for init( was that ancient versions of /ava
co&ldn:t dyna$ically invo!e constr&ctors with ar(&$ents, so there was no way to (ive the
constr&ct&r a 2ervletConfi(+
-04 T5e (o+e in a =inall3 (lau1e :ill ne6er =ail to eGe(ute, rig5t<
Usin( 2yste$+e%it(?@ in try bloc! will not allow finally code to e%ec&te+
-04 Di==eren(e &et:een BET an+ P%T in ?a6a %er6let1<
In ,ET yo&r entire for$ s&b$ission can be encaps&lated in one U9=, li!e a hyperlin!+
1&ery len(th is li$ited to ;AB characters, not sec&re, faster, 1&ic! and easy+
In .#2T >o&r na$e"val&e pairs inside the body of the 5TT. re1&est, which $a!es for
a cleaner U9= and i$poses no si4e li$itations on the for$:s o&tp&t+ It is &sed to send a
ch&n! of data to the server to be processed, $ore versatile, $ost sec&re+

--4 *5at i1 ?a6a %er6let 1e11ion<
The session is an ob)ect &sed by a servlet to trac! a &ser:s interaction with a 0eb
application across $&ltiple 5TT. re1&ests+
-34 *5at i1 1er6let mapping<
The servlet $appin( defines an association between a U9= pattern and a servlet+ The
$appin( is &sed to $ap re1&ests to servlets+
-44 *5at i1 1er6let (onteGt <
The servlet conte%t is an ob)ect that contains a servlet:s view of the 0eb application
within which the servlet is r&nnin(+
Usin( the conte%t, a servlet can lo( events, obtain U9= references to reso&rces, and
set and store attrib&tes that other servlets in the conte%t can &se+
-.4 EGplain Bar&age (olle(tion me(5ani1m in ?a6a
It is done by two ways by reference co&nt & trace a (raph of ob)ect reference+
-64 *5at i1 ?a6a RM$<
9e$ote 8ethod Invocation (98I is the process of activatin( a $ethod on a re$otely
r&nnin( ob)ect+ 98I offers location transparency in the sense that it (ives the feel that a
$ethod is e%ec&ted on a locally r&nnin( ob)ect+
->4 *5at are t5e la3er1 o= RM$ Ar(5ite(ture<
The 98I is b&ilt on three layers+
a. Stub and Skeleton layer
This layer lies )&st beneath the view of the developer+ This layer intercepts $ethod
calls $ade by the client to the interface reference variable and redirects these calls to a
re$ote 98I service+
b. Remote Reference Layer
This layer &nderstands how to interpret and $ana(e references $ade fro$ clients to
the re$ote service ob)ects+ The connection is a one*to*one (&nicast lin!+
c. Transport layer
Prepared by
Ms.A.Subathra Devi
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This layer is based on TC."I. connections between $achines in a networ!+ It
provides basic connectivity, as well as so$e firewall penetration strate(ies+
-@4 7o: man3 t3pe1 o= proto(ol implementation1 +oe1 RM$ 5a6e<
98I has at least three protocol i$ple$entations3
/ava 9e$ote 8ethod .rotocol(/98., Internet Inter #9B .rotocol(II#., and /ini
E%tensible 9e$ote Invocation(/E9I+ These are alternatives, not part of the sa$e thin(, All
three are indeed layer A protocols for those who are still spea!in( #2I reference $odel+
-,4 *5at i1 t5e role o= Remote $nter=a(e in RM$<
The 9e$ote interface serves to identify interfaces whose $ethods $ay be invo!ed
fro$ a non*local virt&al $achine+ Any ob)ect that is a re$ote ob)ect $&st directly or
indirectly i$ple$ent this interface+ 8ethods that are to be invo!ed re$otely $&st be
identified in 9e$ote Interface+ All 9e$ote $ethods sho&ld throw 9e$oteE%ception+
304 *5at i1 t5e role 'a6a4rmi4Naming Cla11<
The Na$in( class provides $ethods for storin( and obtainin( references to re$ote
ob)ects in the re$ote ob)ect re(istry+
304 *5at i1 t5e +e=ault port u1e+ &3 RM$ Regi1tr3<
?BCC
3-4 *5at i1 meant &3 &in+ing in RM$<
Bindin( is a process of associatin( or re(isterin( a na$e for a re$ote ob)ect that can
be &sed at a later ti$e to loo! &p that re$ote ob)ect+ A re$ote ob)ect can be associated
with a na$e &sin( the Na$in( class:s bind or rebind $ethods+
334 *5at i1 t5e +i==eren(e &et:een u1ing &in+() an+ re&in+() met5o+1 o= Naming
Cla11<
bind $ethod(2trin( na$e binds the specified na$e to a re$ote ob)ect while
rebind(2trin( na$e $ethod rebinds the specified na$e to a new re$ote ob)ect,any
e%istin( bindin( for the na$e is replaced+
344 *5en i1 Alrea+32oun+EG(eption t5ro:n an+ &3 :5i(5 met5o+<
AlreadyBo&ndE%ception is thrown by bind(2trin( na$e $ethod when a re$ote
ob)ect is already re(istered with the re(istry with the sa$e na$e+
3.4 7o: to get all t5e regi1tere+ o&'e(t1 in a rmiregi1tr3<
Usin( list $ethod of Na$in( Class+
364 Can a (la11 implementing a Remote inter=a(e 5a6e non remote met5o+1<
>es+ Those $ethods behave as nor$al )ava $ethods operatin( within the /'8+
3>4 *5at i1 t5e proto(ol u1e+ &3 RM$<
/98. ()ava re$ote $ethod protocol
3@4 *5at i1 t5e u1e o= "ni(a1tRemote&'e(t in RM$<
The Unicast9e$ote#b)ect class provides s&pport for point*to*point active ob)ect
references &sin( TC. strea$s+ #b)ects that re1&ire re$ote behavior sho&ld e%tend
Unicast9e$ote#b)ect+
3,4 *5at i1 Porta&leRemote&'e(t4narro:() met5o+ an+ :5at i1 u1e+ =or<
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/ava 98I*II#. provides a $echanis$ to narrow the the #b)ect yo& have received
fro$ fro$ yo&r loo!&p, to the appropriate type+ This is done thro&(h the
)ava%+r$i+.ortable9e$ote#b)ect class and, $ore specifically, &sin( the narrow( $ethod+
404 $n a RM$ Client Program, :5at are t5e eG(petion1 :5i(5 mig5t 5a6e to
5an+le+<
a+ 8al-or$edU9=E%ception
b+ NotBo&ndE%ception
c+ 9e$oteE%ception
404 *5at are t5e 1er6i(e1 in RM$<
An 98I DserviceD co&ld well be any /ava $ethod that can be invo!ed re$otely+ The
other service is the /98. 98I na$in( service which is a loo!&p service+
4-4 *5at i1 t5e ?D2C 340 AP$<
The /DBC E+B A.I is the latest &pdate of the /DBC A.I+ It contains $any feat&res,
incl&din( scrollable res&lt sets and the 2F=3?CCC data types+
Edit
434 Are t5ere an3 D2C +ri6er1 t5at +o not :or8 :it5 t5e ?D2CHD2C 2ri+ge<
8ost #DBC ;+B drivers sho&ld wor! with the Brid(e+ 2ince there is so$e variation in
f&nctionality between #DBC drivers, the f&nctionality of the brid(e $ay be affected+ The
brid(e wor!s with pop&lar .C databases, s&ch as 8icrosoft Access and -o%.ro+
444 7o: +o $ retrie6e a :5ole ro: o= +ata at on(e, in1tea+ o= (alling an in+i6i+ual
Re1ult%et4getIII met5o+ =or ea(5 (olumn<
The 9es&lt2et+(etGGG $ethods are the only way to retrieve data fro$ a 9es&lt2et
ob)ect, which $eans that yo& have to $a!e a $ethod call for each col&$n of a row+ It is
&nli!ely that this is the ca&se of a perfor$ance proble$, however, beca&se it is diffic&lt to
see how a col&$n co&ld be fetched witho&t at least the cost of a f&nction call in any
scenario+ 0e welco$e inp&t fro$ developers on this iss&e+

4.4 Are all t5e reEuire+ ?D2C +ri6er1 to e1ta&li15 (onne(ti6it3 to m3 +ata&a1e part
o= t5e ?DJ<
No+ There arenH:t any /DBC technolo(y*enabled drivers b&ndled with the /DI ?+?+% or
/ava ; .latfor$ releases other than the /DBC*#DBC Brid(e+ 2o, developers need to (et a
driver and install it before they can connect to a database+ 0e are considerin( b&ndlin(
/DBC technolo(y* enabled drivers in the f&t&re+

464 Doe1 t5e ?D2CHD2C 2ri+ge 1upport multiple (on(urrent open 1tatement1 per
(onne(tion<
No+ >o& can open only one 2tate$ent ob)ect per connection when yo& are &sin( the /DBC*
#DBC Brid(e+
4>4 *53 (anKt $ in6o8e t5e Re1ult%et met5o+1 a=ter#a1t an+ &e=ore!ir1t :5en t5e
met5o+ neGt :or81<
>o& are probably &sin( a driver i$ple$ented for the /DBC ?+B A.I+ >o& need to &p(rade to a
/DBC ;+B driver that i$ple$ents scrollable res&lt sets+ Also be s&re that yo&r code has
created scrollable res&lt sets and that the DB82 yo& are &sin( s&pports the$+

4,4 7o: (an $ retrie6e a %tring or ot5er o&'e(t t3pe :it5out (reating a ne: o&'e(t
ea(5 time<
Creatin( and (arba(e collectin( potentially lar(e n&$bers of ob)ects ($illions
&nnecessarily can really h&rt perfor$ance+
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It $ay be better to provide a way to retrieve data li!e strin(s &sin( the /DBC A.I
witho&t always allocatin( a new ob)ect+ 0e are st&dyin( this iss&e to see if it is an area in
which the /DBC A.I sho&ld be i$proved+ 2tay t&ned, and please send &s any co$$ents yo&
have on this 1&estion+

.04 $ :oul+ li8e to +o:nloa+ t5e ?D2CHD2C 2ri+ge =or t5e ?a6a - %DJ, %tan+ar+
E+ition (=ormerl3 ?DJ 04-)4 $LKm a &eginner :it5 t5e ?D2C AP$, an+ $ :oul+ li8e to
1tart :it5 t5e 2ri+ge4 7o: +o $ +o it<
The /DBC*#DBC Brid(e is b&ndled with the /ava ; 2DI, 2tandard Edition, so there is
no need to download it separately+
.04 $= $ u1e t5e ?D2C AP$, +o $ 5a6e to u1e D2C un+erneat5<
No, this is )&st one of $any possible sol&tions+ 0e reco$$end &sin( a p&re /ava
/DBC technolo(y*enabled driver, type E or <, in order to (et all of the benefits of the /ava
pro(ra$$in( lan(&a(e and the /DBC A.I+

.-4 EGplain %er6letConteGt
2ervletConte%t interface is a window for a servlet to view itH:s environ$ent+ A servlet
can &se this interface to (et infor$ation s&ch as initiali4ation para$eters for the web
applicationor servlet containerH:s version+ Every web application has one and only one
2ervletConte%t and is accessible to all active reso&rce of that application

.34 *5at i1 t5e +i==eren(e &et:een 7ttp%er6let an+ Beneri(%er6let<
A ,eneric2ervlet has a service( $ethod ai$ed to handle re1&ests+ 5ttp2ervlet
e%tends ,eneric2ervlet and adds s&pport for do,et(, do.ost(, do5ead( $ethods (5TT.
?+B pl&s do.&t(, do#ptions(, doDelete(, doTrace( $ethods (5TT. ?+?+ Both these
classes are abstract+

54 4 *5at are ?a6a 2ean1<
/ava Beans are &s&al /ava classes which adhere to certain codin( conventions3
► I$ple$ents )ava+io+2eriali4able interface
► .rovides no ar(&$ent constr&ctor
► .rovides (etter and setter $ethods for accessin( it:s properties+
5.4 *53 +o $ get a NullPointerEG(eption :5en loa+ing a ?AR =ile into t5e 2ean2oG<
Us&ally this is beca&se of a $ista!e in the /A9 file bein( loaded+ In the $eanti$e,
typical errors incl&de3
► The 8ANI-E2T file &ses classes &sin( the wron( file separator (D"D sho&ld be &sed in all
platfor$s+
► The 8ANI-E2T file refers to classes in a pac!a(e b&t the act&al +class files are not really
in that pac!a(e+

.64 *5at i1 &ean per1i1tan(e propert3<
A bean has the property of persistence when its properties, fields, and state
infor$ation are saved to and retrieved fro$ stora(e+ Co$ponent $odels provide a
$echanis$ for persistence that enables the state of co$ponents to be stored in a non*
volatile place for later retrieval+
.>4 *5at are eGterniFa&le inter=a(e<
Use the E%ternali4able interface when yo& need co$plete control over yo&r bean:s
seriali4ation (for e%a$ple, when writin( and readin( a specific file for$at+
To &se the E%ternali4able interface yo& need to i$ple$ent two $ethods3 readE%ternal and
writeE%ternal+ Classes that i$ple$ent E%ternali4able $&st have a no*ar(&$ent constr&ctor+
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.@4 *5at i1 propert3 e+itor in 'a6a &ean1<
A property editor is a tool for c&sto$i4in( a partic&lar property type+ .roperty editors
are activated in the .roperties window+ This window deter$ines a property:s type, searches
for a relevant property editor, and displays the property:s c&rrent val&e in a relevant way+
59 4 *53 are (omponent ar(5ite(ture1 u1e=ul<
Developers are t&rnin( to creatin( co$ponents rather than $onolithic applications to
free the$selves fro$ slow, e%pensive application develop$ent, and to b&ild &p a portable,
re&sable code base+ This enables developers to 1&ic!ly attac! new $ar!et opport&nities,
new )oint develop$ent opport&nities, and new ways to sell s$aller pac!a(es of software+
604 $1 ?a6a2ean1 a (omplete (omponent ar(5ite(ture<
/avaBeans is a co$plete co$ponent $odel+ It s&pports the standard co$ponent
architect&re feat&res of properties, events, $ethods, and persistence+ In addition,
/avaBeans provides s&pport for introspection (to allow a&to$atic analysis of a
/avaBeansco$ponent and c&sto$i4ation (to $a!e it easy to confi(&re a /avaBeans
co$ponent+
604 7o: i1 anon3mou1 inner (la11 u1e+ :it5 it1 purpo1e4 C"9 No6;De( -00,D
An anony$o&s class is a !ind of local class that has no na$e, it co$bines the synta%
for class definition with the synta% for ob)ect instantiation+ 0hile a local class definition is a
/ava state$ent, an anony$o&s class definition (and instantiation is a /ava e%pression, so it
can appear as part of a lar(er e%pression, s&ch as $ethod invocation+ Interfaces cannot be
defined anony$o&sly+
6-4 *5at are t5e 1e(urit3 impli(ation1 =or +o:nloa+ing 2ean1 o6er t5e $nternet<
/avaBeans does not add any sec&rity feat&res to the /ava platfor$+ 9ather,
/avaBeans co$ponents have f&ll access to the broad ran(e of sec&rity feat&res that are part
of the /ava platfor$+ /avaBeans co$ponents can be &sed to b&ild a ran(e of different !inds
of sol&tions fro$ f&ll*fled(ed /ava des!top applications to web*based Applets+
634 *5en :ill ?a6a2ean1 &e 1upporte+ on t5e C=ill in t5e &lan8D
plat=orm;operating 131tem<
The co$plete set of /avaBeans A.Is are core to /ava ;, hence any platfor$ that is f&lly
co$patible with /ava ; i$plicitly s&pports /avaBeans+ Th&s, /avaBeans s&pport will be
available as soon as this platfor$"operatin( syste$ vendor s&pports /ava ;+
644 7o: +o 3ou pa(8 a &ean into a ?AR =ile <
Before yo& can brin( a /avaBean into a Bean*enabled vis&al b&ilder tool, it $&st be p&t into
the standard Bean container, which is a /A9 file that incl&des all the Bean classes as well as
a D$anifestD file that says DThis is a Bean+D A $anifest file is si$ply a te%t file that follows a
partic&lar for$+
6.4 *5at i1 an inner (la11< EGplain :it5 an eGample< "9 CNo6;De( -000D
A class within the class is called as an inner class+
class A
J int a, b,c@
class B
J "" codin( for inner class KK
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Part H 2
06 – Mar81 9ue1tion1 :it5 An1:er1
04 "tilit3 Pa(8age1)
 The final /ava pac!a(e, )ava+&til, contains a collection of &tility classes+
 The Utility .ac!a(e of /ava consist of the followin( co$ponents3
⇒ Collections fra$ewor!
⇒ =e(acy collection classes
⇒ Event $odel
⇒ Date and ti$e facilities
⇒ Internationali4ation
⇒ 8iscellaneo&s &tility classes s&ch as strin( to!eni4er, rando$*n&$ber
(enerator and bit array
 Description of the &tility classes of this pac!a(e is as follows
⇒ Data 2tr&ct&re Classes3 Data 2tr&ct&re Classes are very &sef&l classes for
i$ple$entin( standard co$p&ter science data str&ct&res3 incl&din( Bit2et,
Dictionary, 5ashtable, 2tac! and 'ector+ The En&$eration interface of )ava+&til
pac!a(e is &sed to co&nt thro&(h a set of val&es+
⇒ Date3 The Date class is &sed to $anip&late calendar dates in a syste$*
independent fashion+
⇒ 2trin(To!eni4er3 This 2trin(To!eni4er class is &sed to convert a 2trin( of te%t
into its to!ens+
⇒ .roperties3 The properties table contains !ey"val&e pairs where both the !ey
and the val&e are 2trin(s and the class is &sed by the 2yste$ class to
i$ple$ent 2yste$ properties+
⇒ #bserver and #bservable3 Classes that i$ple$ent the #bserver interface can
DwatchD #bservable ob)ects for state chan(es+ 0hen an #bservable ob)ect
chan(es it notifies all of its #bservers of the chan(e+
⇒ 9ando$*N&$ber ,enerator3 The 9ando$ N&$ber ,enerator class is &sed to
(enerate the rando$*n&$bers+
⇒ En&$eration3 The En&$eration interface defines a (eneric pro(ra$$in(
interface for iteratin( thro&(h a set of val&es+
-4 $nput;utput Pa(8age1)
The )ava+io pac!a(e defines I"# in ter$s of strea$s+ 2trea$s are ordered se1&ences
of data that have a so&rce (inp&t strea$s or destination (o&tp&t strea$s+
8ost strea$ types s&pport the $ethods of so$e basic interfaces and abstract classes,
with few additions+
The )ava+nio pac!a(e and its s&bpac!a(es define I"# in ter$s of b&ffers and channels+
B&ffers are data stores (si$ilar to arrays that can be read fro$ or written to+
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Channels represent connections to entities capable of perfor$in( I"# operations,
incl&din( b&ffers, files, and soc!ets+
The )ava+net pac!a(e provides specific s&pport for networ! I"#, based aro&nd the &se
of soc!ets, with an &nderlyin( strea$ or channel*based $odel+
The pac!a(e )ava+io has two $a)or parts3 character strea$s and byte strea$s+
Characters are ?A*bit UT-*?A characters, whereas bytes are (as always L bits+
The character strea$s are &sed for te%t*based I"#, while byte strea$s are &sed for
data*based I"#+
The byte strea$s are called inp&t strea$s and o&tp&t strea$s, and the character
strea$s are called readers and writers
The I#E%ception class is &sed by $any $ethods in )ava+io to si(nal e%ceptional
conditions+ 2o$e e%tended classes of I#E%ception si(nal specific proble$s+
34 23te %tream1)
 The )ava+io pac!a(e defines abstract classes for basic byte inp&t and o&tp&t strea$s+
 All strea$s s&pport the notion of bein( open or closed+ >o& open a strea$ when yo&
create it, and can read or write while it is open+ >o& close a strea$ with its close
$ethod, defined in the Closeable interface+
 A strea$ class co&ld define a finali4e $ethod to release these reso&rces d&rin(
(arba(e collection
 Inp&t2trea$3 The abstract class Inp&t2trea$ declares $ethods to read bytes fro$ a
partic&lar so&rce+ Inp&t2trea$ is the s&perclass of $ost byte inp&t strea$s in
)ava+io+
⇒ p&blic abstract int read( throws I#E%ception
⇒ p&blic int read(byteMN b&f, int offset, int co&nt throws I#E%ception
⇒ p&blic int read(byteMN b&f throws I#E%ception
⇒ p&blic lon( s!ip(lon( co&nt throws I#E%ception
⇒ p&blic int available( throws I#E%ception
⇒ p&blic void close( throws I#E%ception
 #&tp&t2trea$3 The abstract class #&tp&t2trea$ is analo(o&s to Inp&t2trea$@ it
provides an abstraction for writin( bytes to a destination+ Its $ethods are3
⇒ p&blic abstract void write(int b throws I#E%ception
⇒ p&blic void write(byteMN b&f, int offset, int co&nt throws I#E%ception
⇒ p&blic void write(byteMN b&f throws I#E%ception
⇒ p&blic void fl&sh( throws I#E%ception
⇒ p&blic void close( throws I#E%ception
 The i$ple$entation of #&tp&t2trea$ re1&ires only that a s&bclass provide the
sin(le*byte variant of write beca&se the other write $ethods are defined in ter$s of
this one+
 he defa&lt i$ple$entations of fl&sh and close will &s&ally need to be overridden as
appropriate for a partic&lar strea$Oin partic&lar, b&ffered strea$s $ay need to fl&sh
when closed+
 Character 2trea$s3 The abstract classes for readin( and writin( strea$s of
characters are 9eader and 0riter+
 Each s&pports $ethods si$ilar to those of its byte strea$ co&nterpartOInp&t2trea$
and #&tp&t2trea$, respectively+
 9eader has a read $ethod that ret&rns a char as the lowest ?A bits of an int+ And,
0riter has $ethods that write char arrays+
 The character strea$s were desi(ned after the byte strea$s to provide f&ll s&pport
for wor!in( with Unicode characters, and in the process the contracts of the classes
were i$proved to $a!e the$ easier to wor! with+
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 9eader3 The abstract class 9eader provides a character strea$ analo(o&s to the byte
strea$ Inp&t2trea$ and the $ethods of 9eader essentially $irror those of
Inp&t2trea$3
⇒ p&blic int read( throws I#E%ception
⇒ p&blic abstract int read(charMN b&f, int offset, int co&nt throws I#E%ception
⇒ p&blic int read(charMN b&f throws I#E%ception
⇒ p&blic int read()ava+nio+CharB&ffer b&f throws I#E%ception
⇒ p&blic lon( s!ip(lon( co&nt throws I#E%ception
⇒ p&blic boolean ready( throws I#E%ception
⇒ p&blic abstract void close( throws I#E%ception
 The i$ple$entation of 9eader re1&ires that a s&bclass provide an i$ple$entation of
both the read $ethod that reads into a char array, and the close $ethod+
 There are a n&$ber of differences between 9eader and Inp&t2trea$+
 0ith 9eader the f&nda$ental readin( $ethod reads into a char array and the other
read $ethods are defined in ter$s of this $ethod+
 In contrast the Inp&t2trea$ class &ses the sin(le*byte read $ethod as its
f&nda$ental readin( $ethod+
 0riter3 The abstract class 0riter provides a strea$ analo(o&s to #&tp&t2trea$ b&t
desi(ned for &se with characters instead of bytes+
 The $ethods of 0riter essentially $irror those of #&tp&t2trea$, b&t add so$e other
&sef&l for$s of write3
⇒ p&blic void write(int ch throws I#E%ception
⇒ p&blic abstract void write(charMN b&f, int offset, int co&nt throws I#E%ception
⇒ p&blic void write(charMN b&f throws I#E%ception
⇒ p&blic void write(2trin( str, int offset, int co&nt throws I#E%ception
⇒ p&blic void write(2trin( str throws I#E%ception
⇒ p&blic abstract void fl&sh( throws I#E%ception
⇒ p&blic abstract void close( throws I#E%ception
 2&bclasses of 0riter $&st i$ple$ent the array writin( variant of write, the close
$ethod, and the fl&sh $ethod+
 0riter also i$ple$ents the )ava+lan(+Appendable interface+ The append(charc
$ethod is e1&ivalent to write(c@ the append $ethods that ta!e a Char2e1&ence are
e1&ivalent to passin( the 2trin( representations of the Char2e1&ence ob)ects to the
write(2trin(str $ethod+
 Inp&t2trea$9eader and #&tp&t2trea$0riter3 The conversion strea$s
Inp&t2trea$9eader and #&tp&t2trea$0riter translate between character and byte
strea$s &sin( either a specified character set encodin( or the defa&lt encodin( for
the local syste$+
 An Inp&t2trea$9eader ob)ect is (iven a byte inp&t strea$ as its so&rce and
prod&ces the correspondin( UT-*?A characters+ An #&tp&t2trea$0riter ob)ect is
(iven a byte o&tp&t strea$ as its destination and prod&ces encoded byte for$s of
the UT-*?A characters written on it+
⇒ p&blic Inp&t2trea$9eader(Inp&t2trea$ in
⇒ p&blic Inp&t2trea$9eader(Inp&t2trea$ in, Charset c
⇒ p&blic Inp&t2trea$9eader(Inp&t2trea$ in, CharsetDecoder c
⇒ p&blic Inp&t2trea$9eader(Inp&t2trea$ in, 2trin( enc throws
Uns&pportedEncodin(E%ception
⇒ p&blic #&tp&t2trea$0riter(#&tp&t2trea$ o&t
⇒ p&blic #&tp&t2trea$0riter(#&tp&t2trea$ o&t, Charset c
⇒ p&blic #&tp&t2trea$0riter(#&tp&t2trea$ o&t, CharsetEncoder c
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⇒ p&blic #&tp&t2trea$0riter(#&tp&t2trea$ o&t, 2trin( enc throws
Uns&pportedEncodin(E%ception
 The read $ethods of Inp&t2trea$9eader si$ply read bytes fro$ their associated
Inp&t2trea$ and convert the$ to characters &sin( the appropriate encodin( for that
strea$+
 The write $ethods of #&tp&t2trea$0riter ta!e the s&pplied characters, convert
the$ to bytes with the appropriate encodin(, and write the$ to the associated
#&tp&t2trea$+
 The -ile9eader and -ile0riter classes are s&bclasses of these conversion strea$s+
This helps yo& read and write local files correctly in a consistent, Unicode*savvy
fashion &sin( the local encodin(+
44 $llu1trate :it5 a ?a6a Program a +e=ine an+ u1e an inner (la114
C"9 No6;De( -000D
 There are fo&r other types of classes, loosely !nown as inner classes, that can be
defined in a /ava pro(ra$+ Used correctly, inner classes are an ele(ant and powerf&l
feat&re of the /ava lan(&a(e+ These fo&r types of classes are s&$$ari4ed here3
⇒ 2tatic $e$ber classes
 A static $e$ber class is a class (or interface defined as a static
$e$ber of another class+
 A static $ethod is called a class $ethod, so, by analo(y, we co&ld call
this type of inner class a Dclass class,D b&t this ter$inolo(y wo&ld
obvio&sly be conf&sin(+
 A static $e$ber class behaves $&ch li!e an ordinary top*level class,
e%cept that it can access the static $e$bers of the class that contains
it+ Interfaces can be defined as static $e$bers of classes+
⇒ 8e$ber classes
 A $e$ber class is also defined as a $e$ber of an enclosin( class, b&t
is not declared with the static $odifier+ This type of inner class is
analo(o&s to an instance $ethod or field+
 An instance of a $e$ber class is always associated with an instance of
the enclosin( class, and the code of a $e$ber class has access to all
the fields and $ethods (both static and non*static of its enclosin(
class+
 There are several feat&res of /ava synta% that e%ist specifically to wor!
with the enclosin( instance of a $e$ber class+ Interfaces can only be
defined as static $e$bers of a class, not as non*static $e$bers+
⇒ =ocal classes
 A local class is a class defined within a bloc! of /ava code+ =i!e a local
variable, a local class is visible only within that bloc!+
 Altho&(h local classes are not $e$ber classes, they are still defined
within an enclosin( class, so they share $any of the feat&res of
$e$ber classes+
 Additionally, however, a local class can access any final local variables
or para$eters that are accessible in the scope of the bloc! that defines
the class+ Interfaces cannot be defined locally+
⇒ Anony$o&s classes
 An anony$o&s class is a !ind of local class that has no na$e@ it
co$bines the synta% for class definition with the synta% for ob)ect
instantiation+
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13
 0hile a local class definition is a /ava state$ent, an anony$o&s class
definition (and instantiation is a /ava e%pression, so it can appear as
part of a lar(er e%pression, s&ch as $ethod invocation+
 Interfaces cannot be defined anony$o&sly+
 The $ost i$portant feat&re of the inner class is that it allows &s to t&rn thin(s into
ob)ects that we nor$ally wo&ldn:t t&rn into ob)ects+ That allows o&r code to be even
$ore ob)ect*oriented than it wo&ld be witho&t inner classes
 An inner class allows &s to re$ove that lo(ic and place it into its own class+ 2o fro$
an ob)ect*oriented point of view, we:ve ta!en f&nctionality o&t of where it doesn:t
belon( and have p&t it into its own class+
 #b)ect*oriented desi(n isn:t everyone:s thin(, b&t l&c!ily, inner classes provide $ore+
-ro$ an or(ani4ational point of view, inner classes allow &s to f&rther or(ani4e o&r
pac!a(e str&ct&re thro&(h the &se of na$espaces+ Instead of d&$pin( everythin( in
a flat pac!a(e, classes can be f&rther nested within classes+
 Inner classes have their disadvanta(es+ -ro$ a $aintenance point of view,
ine%perienced /ava developers $ay find the inner class diffic&lt to &nderstand+ The
&se of inner classes will also increase the total n&$ber of classes in yo&r code+
.4 ?a6a Data&a1e Conne(ti6it3)
 /ava Database Connectivity or in short /DBC is a technolo(y that enables the )ava
pro(ra$ to $anip&late data stored into the database+
 /DBC is /ava application pro(ra$$in( interface that allows the /ava pro(ra$$ers to
access database $ana(e$ent syste$ fro$ /ava code+ It was developed by /ava2oft,
a s&bsidiary of 2&n 8icrosyste$s+
 /DBC is consists of fo&r Co$ponents3 The /DBC A.I, /DBC Driver 8ana(er, The /DBC
Test 2&ite and /DBC*#DBC Brid(e+
 /DBC is an A.I specification developed by 2&n 8icrosyste$s that defines a &nifor$
interface for accessin( vario&s relational databases+ /DBC is a core part of the /ava
platfor$ and is incl&ded in the standard /DI distrib&tion+
/DBC Driver 8ana(er3
 The /DBC Driver8ana(er class defines ob)ects which can connect /ava applications to
a /DBC driver+ Driver8ana(er has traditionally been the bac!bone of the /DBC
architect&re+
 Its $ain p&rpose is to provide a $eans of $ana(in( the different types of /DBC
database driver+
 0hen openin( a connection to a database it is the Driver8ana(er: s role to choose
the $ost appropriate driver fro$ the previo&sly loaded drivers+
 A /ava pro(ra$ that &ses the /DBC A.I loads the specified driver for a partic&lar
DB82 before it act&ally connects to a database+ The /DBC Driver8ana(er class then
sends all /DBC A.I calls to the loaded driver+
 Types of /DBC drivers3 There are fo&r types of /DBC drivers !nown as3
⇒ /DBC*#DBC brid(e pl&s #DBC driver, also called Type ?+
⇒ Native*A.I, partly /ava driver, also called Type ;+
⇒ /DBC*Net, p&re /ava driver, also called Type E+
⇒ Native*protocol, p&re /ava driver, also called Type <+
 The $ethod Class+forNa$e(2trin( is &sed to load the /DBC driver class+ In /DBC
<+B, it:s no lon(er necessary to e%plicitly load /DBC drivers &sin( Class+forNa$e(+
 0hen a connection is needed, one of the Driver8ana(er+(etConnection( $ethods is
&sed to create a /DBC connection+
Prepared by
Ms.A.Subathra Devi
14
 The U9= &sed is dependent &pon the partic&lar /DBC driver+ It will always be(in with
the D)dbc3D protocol, b&t the rest is &p to the partic&lar vendor+ #nce a connection is
established, a state$ent $&st be created+
64 *5at i1 t5e li=e(3(le o= a 1er6let< *rite 15ort note1 on t5e =ollo:ing (la11e1)
Beneri1%er6let, %er6let$nput%tream, %er6letutput%tream M
%er6letEG(eption4 C"9 No6;De( -000D
 2ervlets are /ava technolo(y:s answer to C,I pro(ra$$in(+ They are pro(ra$s that
r&n on a 0eb server and b&ild 0eb pa(es+
Lifecycle of a Servlet
 The 2ervlet lifecycle consists of the followin( steps3
⇒ The 2ervlet class is loaded by the container d&rin( start*&p+
⇒ The container calls the init( $ethod+ This $ethod initiali4es the servlet and
$&st be called before the servlet can service any re1&ests+ In the entire life of
a servlet, the init( $ethod is called only once+
⇒ After initiali4ation, the servlet can service client*re1&ests+ Each re1&est is
serviced in its own separate thread+ The container calls the service( $ethod
of the servlet for every re1&est+ The service( $ethod deter$ines the !ind of
re1&est bein( $ade and dispatches it to an appropriate $ethod to handle the
re1&est+ The developer of the servlet $&st provide an i$ple$entation for
these $ethods+ If a re1&est for a $ethod that is not i$ple$ented by the
servlet is $ade, the $ethod of the parent class is called, typically res&ltin( in
an error bein( ret&rned to the re1&ester+
⇒ -inally, the container calls the destroy( $ethod which ta!es the servlet o&t of
service+ The destroy( $ethod li!e init( is called only once in the lifecycle of a
2ervlet+
GenerisServlet:
This class i$ple$ents 2ervlet and 2ervletConfi( interfaces+ This class can be e%tended
by a servlet+ It is a co$$on practice that a servlet class e%tends protocol*specific, s&ch as
5ttp2ervlet class+ 0ith the help of &sin( life cycle $ethods, it $a!es si$pler and easier to
develop servlets applications+ To write a (eneric servlet, the developer need only to override
the service( $ethod+ Additionally, the lo( $ethod of 2ervletConte%t interface is also
i$ple$ented by ,eneric2ervlet+
ServletInputStream:
.rovides an inp&t strea$ for readin( binary data fro$ a client re1&est, incl&din( an
efficient read=ine $ethod for readin( data one line at a ti$e+ 0ith so$e protocols, s&ch as
5TT. .#2T and .UT, a 2ervletInp&t2trea$ ob)ect can be &sed to read data sent fro$ the
client+ A 2ervletInp&t2trea$ ob)ect is nor$ally retrieved via the
2ervlet9e1&est+(etInp&t2trea$( $ethod+ This is an abstract class that a servlet container
i$ple$ents+ 2&bclasses of this class $&st i$ple$ent the )ava+io+Inp&t2trea$+read(
$ethod+
ServletOutputStream:
2ervleto&tp&tstrea$ is &sed for sendin( data to client in binary for$at+ It is retrieved
via response+(et#&tp&t2trea$( f&nction+ 2ervlet#&tp&t2trea$ is an abstract class and
servlet container i$ple$ents it+ 0hen yo& &se character conversion and there is a lot of
te%t then it is better to &se byteMN instead of 2trin( ob)ect+ ByteArray#&tp&t2trea$
Prepared by
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15
i$ple$ents o&tp&t strea$ and it contain data in for$ of byte array+-or retrievin( data yo&
can &se toByteArray( and to2trin(( $ethods+
ServletException:
2ervletE%ception is a s&bclass of the E%ception+ It defines a (eneral e%ception a servlet
can throw when it enco&nters diffic&lty+ 2ervletE%ception class define only one $ethod
(et9ootCa&se( that ret&rns the e%ception that ca&sed this servlet e%ception+ It inherit the
other $ethods li!e fillIn2tac!Trace, (et=ocali4ed8essa(e, (et8essa(e, print2tac!Trace,
print2tac!Trace, print2tac!Trace, to2trin( etc fro$ the Throwable class+ .ac!a(es that &se
2ervletE%ception 3 P )ava%+servlet P )ava%+servlet+http
>4 De1ign an appli(ation :5i(5 implement1 RM$ Con(ept14 C"9 No6;De( -00,D
 9e$ote 8ethod Invocation (98I facilitates ob)ect f&nction calls between /ava 'irt&al
8achines (/'8s+
 /'8s can be located on separate co$p&ters * yet one /'8 can invo!e $ethods
belon(in( to an ob)ect stored in another /'8+ 8ethods can even pass ob)ects that a
forei(n virt&al $achine has never enco&ntered before, allowin( dyna$ic loadin( of
new classes as re1&ired+
 0ritin( yo&r own 98I services can be a little diffic&lt at first+
 The first thin( we need to do is to a(ree &pon an interface, an interface is a
description of the $ethods we will allow re$ote clients to invo!e+ An interface is a
$ethod which contains abstract $ethods@ these $ethods $&st be i$ple$ented by
another class+ #&r interface e%tends )ava+r$i+9e$ote, which indicates that this is a
re$ote service+ And the ne%t step is to i$ple$ent the interface+
 I$ple$entin( the interface is a little tric!ier+ The real code we need to be concerned
abo&t is the constr&ctor and $ain $ethod+
 0e have to declare a defa&lt constr&ctor, even when we don:t have any initiali4ation
code for o&r service+ This is beca&se o&r defa&lt constr&ctor can throw a
)ava+r$i+9e$oteE%ception, fro$ its parent constr&ctor in Unicast9e$ote#b)ect+
 #&r i$ple$entation of the service also needs to have a $ain $ethod+ The $ain
$ethod will be responsible for creatin( an instance of o&r .ower2ervice2erver, and
re(isterin( (or bindin( the service with the 98I 9e(istry+
 #&r $ain $ethod will also assi(n a sec&rity $ana(er to the /'8, to prevent any
nasty s&rprises fro$ re$otely loaded classes+ In this case, a sec&rity $ana(er isn:t
really needed, b&t in $ore co$ple% syste$s where &ntr&sted clients will be &sin( the
service, it is critical+
 0ritin( clients is the easy part * all a client has to do is call the re(istry to obtain a
reference to the re$ote ob)ect, and call its $ethods+ All the &nderlyin( networ!
co$$&nication is hidden fro$ view, which $a!es 98I clients si$ple+
 #&r client $&st first assi(n a sec&rity $ana(er, and then obtain a reference to the
service+ Note that the client receives an instance of the interface we defined earlier,
and not the act&al i$ple$entation+ 2o$e behind*the*scenes wor! is (oin( on, b&t
this is co$pletely transparent to the client+
 To identify a service, we specify an 98I U9=+ The U9= contains the hostna$e on
which the service is located, and the lo(ical na$e of the service+
 /ava 98I is a &sef&l $echanis$ for invo!in( $ethods of re$ote ob)ects+ /ava 98I
allows one /ava 'irt&al 8achine to invo!e $ethods of another, and to share any /ava
ob)ect type, even if client or server has never co$e across that ob)ect type before+
@4 *5at i1 ?a6a 2ean1< Enumerate it1 a+6antage14 C"9 No6;De( -00,D

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 A /ava Bean is a re&sable software co$ponent that wor!s with /ava+ 8ore
specifically3 a /ava Bean is a re&sable software co$ponent that can be vis&ally
$anip&lated in b&ilder tools+
 .ractically, they are classes written in the /ava pro(ra$$in( lan(&a(e confor$in( to
a partic&lar convention+ They are &sed to encaps&late $any ob)ects into a sin(le
ob)ect (the bean, so that they can be passed aro&nd as a sin(le bean ob)ect instead
of as $&ltiple individ&al ob)ects+
 In order to f&nction as a /avaBean class, an ob)ect class $&st obey certain
conventions abo&t $ethod na$in(, constr&ction, and behavior+
 The re1&ired conventions are3
⇒ The class $&st have a no*ar(&$ent p&blic constr&ctor+ This allows easy
instantiation within editin( and activation fra$ewor!s+
⇒ The class properties $&st be accessible &sin( (et, set, and other $ethods
followin( a standard na$in( convention+ This allows easy a&to$ated
inspection and &pdatin( of bean state within fra$ewor!s, $any of which
incl&de c&sto$ editors for vario&s types of properties+
⇒ The class sho&ld be seriali4able+ This allows applications and fra$ewor!s to
reliably save, store, and restore the bean:s state in fashion that is
independent of the '8 and platfor$+
 .roperties are attrib&tes of a Bean that are referenced by na$e+ These properties
are &s&ally read and written by callin( $ethods on the Bean specifically created for
that p&rpose+
 The $ethods of a Bean are )&st the /ava $ethods e%posed by the class that
i$ple$ents the Bean+ These $ethods represent the interface &sed to access and
$anip&late the co$ponent+
 Events are the $echanis$ &sed by one co$ponent to send notifications to another+
#ne co$ponent can re(ister its interest in the events (enerated by another+
0henever the event occ&rs, the interested co$ponent will be notified by havin( one
of its $ethods invo!ed+
 Introspection is the process of e%posin( the properties, $ethods, and events that a
/avaBean co$ponent s&pports+ This process is &sed at r&n*ti$e, as well as by a
vis&al develop$ent tool at desi(n*ti$e+ The defa&lt behavior of this process allows
for the a&to$atic introspection of any Bean+
 0hen yo& are &sin( a vis&al develop$ent tool to asse$ble co$ponents into
applications, yo& will be presented with so$e sort of &ser interface for c&sto$i4in(
Bean attrib&tes+ These attrib&tes $ay affect the way the Bean operates or the way it
loo!s on the screen+
 It is necessary that Beans s&pport a lar(e variety of stora(e $echanis$s+ This way,
Beans can participate in the lar(est n&$ber of applications+ The si$plest way to
s&pport persistence is to ta!e advanta(e of /ava #b)ect 2eriali4ation+ This is an
a&to$atic $echanis$ for savin( and restorin( the state of an ob)ect+
 There is no re1&ire$ent that a Bean be visible at r&n*ti$e+ It is perfectly reasonable
for a Bean to perfor$ so$e f&nction that does not re1&ire it to present an interface
to the &ser@ the Bean $ay be controllin( access to a specific device or data feed+
 The iss&e of $&ltithreadin( is no different in /avaBeans than it is in conventional
/ava pro(ra$$in(+ The /avaBeans architect&re doesn:t introd&ce any new lan(&a(e
constr&cts or classes to deal with threadin(+
 Beans are s&b)ected to the sa$e sec&rity $odel as standard /ava pro(ra$s+ >o&
sho&ld ass&$e that yo&r Bean is r&nnin( in an &ntr&sted applet+ >o& sho&ldn:t $a!e
any desi(n decisions that re1&ire yo&r Bean to be r&n in a tr&sted environ$ent+
Prepared by
Ms.A.Subathra Devi
17
9. EGplain RM$ Ar(5ite(ture<
&ses a layered architect&re, each of the layers co&ld be enhanced or replaced witho&t
affectin( the rest of the syste$+ The details of layers can be s&$$arised as follows3
?+ Application =ayer3 The client and server pro(ra$
;+ 2t&b & 2!eleton =ayer3 Intercepts $ethod calls $ade by the client"redirects these calls to
a re$ote 98I service+
E+9e$ote 9eference =ayer3 Understands how to interpret and $ana(e references $ade
fro$ clients to the re$ote service ob)ects+
<+Transport layer3 Based on TC."I. connections between $achines in a networ!+ It provides
basic connectivity, as well as so$e firewall penetration strate(ies+
004 7o: +o 3ou pa(8 an applet into a ?AR =ile <
An i$portant &se of the /A9 &tility is to opti$i4e applet loadin(+ In /ava ?+B, people
tended to try to cra$ all their code into a sin(le applet class so the client wo&ld need only a
sin(le server hit to download the applet code+ Not only did this res&lt in $essy, hard*to*read
(and $aintain pro(ra$s, b&t the +class file was still &nco$pressed so downloadin(
wasnQRSt as fast as it co&ld have been+ /A9 files solve the proble$ by co$pressin( all of
yo&r +class files into a sin(le file that is downloaded by the browser+ Now yo& can create the
ri(ht desi(n witho&t worryin( abo&t how $any +class files it will (enerate, and the &ser will
(et a $&ch faster download ti$e+
004 *rite 15ort note1 on T3pe 0) ?D2CHD2C 2ri+ge plu1 D2C Dri6er M it1 t3pe1)
Type 1: JDBC-ODBC Brd!e plus ODBC Dr"er:
The first type of /DBC driver is the /DBC*#DBC Brid(e+ It is a driver that provides
/DBC access to databases thro&(h #DBC drivers+ The #DBC driver $&st be confi(&red on
the client for the brid(e to wor!+ This driver type is co$$only &sed for prototypin( or when
there is no /DBC driver available for a partic&lar DB82+
Type #: $at"e-%&' partly-Ja"a Dr"er:
Native*A.I partly*/ava Driver3 The Native to A.I driver converts /DBC co$$ands to
DB82*specific native calls+ This is $&ch li!e the restriction of Type ? drivers+ The client $&st
have so$e binary code loaded on its $achine+ These drivers do have an advanta(e over
Type ? drivers beca&se they interface directly with the database+

Type (: JDBC-$et &ure Ja"a Dr"er:
/DBC*Net .&re /ava Driver3 The /DBC*Net drivers are a three*tier sol&tion+ This type
of driver translates /DBC calls into a database*independent networ! protocol that is sent to
a $iddleware server+ This server then translates this DB82*independent protocol into a
DB82*specific protocol, which is sent to a partic&lar database+ The res&lts are then ro&ted
bac! thro&(h the $iddleware server and sent bac! to the client+ This type of sol&tion $a!es
it possible to i$ple$ent a p&re /ava client+ It also $a!es it possible to swap databases
witho&t affectin( the client+
Type ): $at"e-&rotocol &ur Ja"a Dr"er:
Native*.rotocol .&r /ava Driver These are p&re /ava drivers that co$$&nicate
directly with the vendorH:s database+ They do this by convertin( /DBC co$$ands directly
into the database en(ineH:s native protocol+ This driver has no additional translation or
$iddleware layer, which i$proves perfor$ance tre$endo&sly+
0-4 De1ign an appli(ation =or online &oo8 1elling u1ing %er6let M ?D2C4
9CNo6;De( -00,D
Prepared by
Ms.A.Subathra Devi
18
?,o to the start*7Control .anel*7Ad$inistrative Tools*7 data so&rces+
;Clic! Add b&tton and select the driver 8icrosoft Access Driver(P+$db+
EAfter selectin( the driver, clic! finish b&tton+
<Then (ive Data 2o&rce Na$e and clic! o! b&tton+
T>o&r D2N will (et created+
A Co$pile yo&r servlet and restart the server and r&n yo&r servlet+
servlet code3
i$port )ava+io+P@
i$port )ava+lan(+P@
i$port )ava+s1l+P@
i$port )ava%+servlet+P@
i$port )ava%+servlet+http+P@
p&blic class 2ervletInsertin(DataUsin(5t$l e%tends 5ttp2ervletJ
p&blic void do.ost(5ttp2ervlet9e1&est re1&est, 5ttp2ervlet9esponse response throws
2ervletE%ception, I#E%ceptionJ
response+setContentType(Dte%t"ht$lD@
.rint0riter pw U response+(et0riter(@
2trin( connectionU9= U D)dbc3odbc3st&dentD@
Connection connection@
tryJ 2trin( &serna$e U re1&est+(et.ara$eter(D&serna$eD@
2trin( password U re1&est+(et.ara$eter(DpasswordD@
pw+println(&serna$e@
pw+println(password@
Class+forNa$e(Ds&n+)dbc+odbc+/dbc#dbcDriverD@
connection U Driver8ana(er+(etConnection(connectionU9=@
.repared2tate$ent pst U connection+prepare2tate$ent(Dinsert into
lo(in(&serna$e,password val&es(V,VD@
pst+set2trin((?,&serna$e@
pst+set2trin((;,password@
int i U pst+e%ec&teUpdate(@
if(iWUBJ
pw+println(D9ecord has been insertedD@
K
elseJ
pw+println(D-ailed to insert the dataD@
K
K
catch (E%ception eJ
pw+println(e@
K
K
K
034 Create a "R#Conne(tion u1ing t5e penConne(tion() met5o+ o= a "R# o&'e(t
an+ t5en u1e it to eGamine t5e +o(umentA1 propertie1 an+ (ontent4
C"9 No6;De( -000D
 E%a$ple3
i$port )ava+s1l+P@
p&blic class 8ys1lConnect
Prepared by
Ms.A.Subathra Devi
19
J
p&blic static void $ain(2trin(MN ar(s
J
2yste$+o&t+println(D8y2F= Connect E%a$ple+D@
Connection conn U n&ll@
2trin( &rl U D)dbc3$ys1l3""localhost3EEBA"D@
2trin( dbNa$e U D)dbct&torialD@
2trin( driver U Dco$+$ys1l+)dbc+DriverD@
2trin( &serNa$e U DrootD@
2trin( password U DrootD@
try
J
Class+forNa$e(driver+newInstance(@
conn U
Driver8ana(er+(etConnection(&rlXdbNa$e,&serNa$e,password@
2yste$+o&t+println(DConnected to the databaseD@
conn+close(@
2yste$+o&t+println(DDisconnected fro$ databaseD@
K
catch (E%ception e
J
e+print2tac!Trace(@
K
K
K
"N$VER%$T/ 9"E%T$N%
PART – A
?+ 0hat are the p&rpose of 2ervletsV M9ef+ F+No3 ?BN
;+ 5ow is anony$o&s inner class &sed with its p&rpose+ M9ef+ F+No3 A?N
E+ 0hat is an inner classV E%plain with an e%a$pleV M9ef+ F+No3 ATN
<+ Define 2ervlet =ife Cycle M9ef+ F+No3 ?EN
PART – 2
?+ Desi(n an application which i$ple$ents 98I Concepts+ M9ef+ F+No3 YN
;+ Desi(n an application for online boo! sellin( &sin( 2ervlet & /DBC+ M9ef+ F+No3 ??N
E+ Ill&strate with a /ava .ro(ra$ a define and &se an inner class+ M9ef+ F+No3 <N
<+ 0hat is the lifecycle of a servletV 0rite short notes on the followin( classes3
,eneris2ervlet, 2ervletInp&t2trea$, 2ervlet#&tp&t2trea$ & 2ervletE%ception+
M9ef+ F+No3 AN
T+ 0hat is /ava BeansV En&$erate its advanta(es+ M9ef+ F+No3 LN
A+ Create a U9=Connection &sin( the #penConnection( $ethod of a U9= ob)ect and
then &se it to e%a$ine the doc&$entZs properties and content+ M9ef+ F+No3 ?EN
Prepared by
Ms.A.Subathra Devi
20
Prepared by
Ms.A.Subathra Devi