Head First Servlets and JSP phần 2 ppsx

... GET and have to put them in the Request line.NO body just the header info.*(7DQG 326 7NO request parameters up here.Chapter 4. Being a ServletChapter 4. Being a Servlet Head First Servlets ... !ERG\!KWPO!6HUYOHWVHQGVEDFNDUHVSRQVHZLWKDJHQHUDWHG+70/SDJH6HUYOHWVHQGVEDFNDUHVSRQVHZLWKDJHQHUDWHG+70/SDJH,GHPSRWHQW 127 ,GHPSRWHQWChapter 4. Being a ServletChapter 4. Being a Servlet Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: ... 4XHVWLRQV47HOIMPLEMENTSTHEINTERFACESFOR(TTP3ERVLET2EQUEST AND (TTP3ERVLET2ESPONSE!RETHOSECLASSESINTHE!0)$4HE#ONTAINER AND .O4HECLASSESARENTINTHE!0)BECAUSETHEYRELEFTTOTHEVENDORTOIMPLEMENT4HEGOODNEWSISYOUDONTHAVETOWORRYABOUTIT*USTTRUSTTHATWHENTHESERVICEMETHODISCALLEDINYOURSERVLETITLLBEHANDEDREFERENCESTOTWOPERFECTLYGOODOBJECTSTHATIMPLEMENT(TTP3ERVLET2EQUEST AND (TTP3ERVLET2ESPONSE9OUSHOULDNEVERCAREABOUTTHEACTUALIMPLEMENTATIONCLASSNAMEORTYPE!LLYOUCAREABOUTISTHATYOULLGETSOMETHINGTHATHASALLTHEFUNCTIONALITYFROM(TTP3ERVLET2EQUEST AND (TTP3ERVLET2ESPONSE)NOTHERWORDSALLYOUNEEDTOKNOWARETHEMETHODSYOUCANCALLONTHEOBJECTSTHE#ONTAINERGIVESYOUASPARTOFTHEREQUEST4HEACTUALCLASSINWHICHTHEYREIMPLEMENTEDDOESNTMATTERTOYOUYOUREREFERRINGTOTHEREQUEST AND RESPONSEOBJECTSONLYBYTHEINTERFACETYPE4!M)READINGTHIS5-,CORRECTLY!RETHOSEINTERFACESEXTENDINGINTERFACES$9ES2EMEMBERINTERFACESCANHAVETHEIROWNINHERITANCETREE7HENONEINTERFACEEXTENDSANOTHERINTERFACEWHICHISALLTHEYCANDOINTERFACESCANTIMPLEMENTINTERFACESITMEANSTHATWHOEVERIMPLEMENTSANINTERFACEMUSTIMPLEMENTALLTHEMETHODSDEFINEDINBOTHTHEINTERFACE AND ITSSUPERINTERFACES4HISMEANSFOREXAMPLETHATWHOEVERIMPLEMENTS(TTP3ERVLET2EQUESTMUSTPROVIDEIMPLEMENTATIONMETHODSFORTHEMETHODSDECLAREDINTHE(TTP3ERVLET2EQUESTINTERFACE AND THEMETHODSINTHE3ERVLET2EQUESTINTERFACE4)MSTILLCONFUSEDABOUTWHYTHERESA'ENERIC3ERVLET AND 3ERVLET2EQUEST AND 3ERVLET2ESPONSE)FNOBODYSDOINGANYTHINGEXCEPT(440 SERVLETS THENWHATSTHEPOINT$7EDIDNTSAYNOBODY3OMEBODYSOMEWHEREONECOULDIMAGINEISUSINGTHESERVLETTECHNOLOGYMODELWITHOUTTHE(440PROTOCOL*USTNOBODYWEVEMETPERSONALLYORREADABOUT%VER3TILLTHEFLEXIBILITYWASDESIGNEDINTOTHESERVLETMODELFORTHOSEWHOMIGHTWANTTOUSE SERVLETS WITHSAY3-40ORPERHAPSAPROPRIETARYCUSTOMPROTOCOL4HEONLYSUPPORTBUILTINTOTHE!0)THOUGHISFOR(440 AND THATSWHATVIRTUALLYEVERYONESUSING7KHH[DPGRHVQ¶WH[SHFW\RXWRNQRZKRZWRGHYHORSZLWKQRQ+773VHUYOHWV<RX¶UHQRWH[SHFWHGWRNQRZDQ\WKLQJDERXWKRZ\RXPLJKWXVHVHUYOHWVZLWKDSURWRFRORWKHUWKDQ+773<RXDUHKRZHYHUVWLOOVXSSRVHGWRNQRZKRZWKHFODVVKLHUDUFK\ZRUNV6R\RX&apos ;2 KDYHWRNQRZWKDW+WWS6HUYOHW5HTXHVWDQG+WWS6HUYOHW5HVSRQVHH[WHQGIURP6HUYOHW5HTXHVWDQG6HUYOHW5HVSRQVHDQGWKDWPRVWRIDQ+WWS6HUYOHW¶VLPSOHPHQWDWLRQDFWXDOO\FRPHVIURP*HQHULF6HUYOHW%XWWKDW¶VLW7KHH[DPDVVXPHV\RX¶UHDQ+WWS6HUYOHWGHYHORSHUChapter...

... session.4)SNTTHECODEABOVEJUSTASTUPIDINEFlCIENTWAYTODOTHESAMETHINGASTHEOPPOSITEPAGE)NTHEENDYOUSTILLCREATEDANEWSESSION$9OURERIGHT4HECODEABOVEISJUSTFORTESTINGHOWTHETWODIFFERENTVERSIONSOFGET3ESSIONWORK)NTHEREALWORLDTHEONLYTIMEYOUDWANTTOUSEGET3ESSIONFALSEISIFYOUDO./4WANTTOCREATEANEWSESSION)FYOURGOALISTOCREATEANEWSESSIONBUTSTILLRESPONDDIFFERENTLYIFYOUKNOWTHISISANEWVERSUSPREEXISTINGSESSIONTHENUSETHENOARGGET3ESSIONMETHOD AND SIMPLYASKTHESESSIONIFITSNEWUSINGTHE(TTP3ESSIONIS.EWMETHOD43OITLOOKSLIKEGET3ESSIONTRUEISEXACTLYTHESAMEASGET3ESSION$2IGHTAGAIN4HENOARGVERSIONISACONVENIENCEFORTHOSETIMESWHENYOUKNOWTHATYOUALWAYSWANTASESSIONNEWOREXISTING4HEVERSIONTHATTAKESABOOLEANISUSEFULWHENYOUKNOWTHATYOUDONTWANTANEWSESSIONORWHENTHEDECISIONOFWHETHERTOMAKEANEWSESSIONHAPPENSATRUNTIME AND YOUREPASSINGAVARIABLEINTOTHEGET3ESSIONSOME"OOLEANMETHODChapter 6. Conversational stateChapter 6. Conversational state Head First Servlets and JSP By Bert Bates, ... URL.47AITAMINUTEHOW$/%3THE#ONTAINERKNOWTHATCOOKIESARENTWORKING!TWHATPOINTDOESTHE#ONTAINERDECIDETOUSE 52, REWRITING$!REALLYDUMB#ONTAINERDOESNTCAREWHETHERCOOKIESWORKORNOTTHEDUMB#ONTAINERWILLALWAYSATTEMPTTOSENDTHECOOKIE!.$DO 52, REWRITINGEACHTIMEEVENIFCOOKIESAREWORKING"UTHERESHOWADECENT#ONTAINERHANDLESIT7HENTHE#ONTAINERSEESACALLTOGET3ESSION AND THE#ONTAINERDIDNTGETASESSION)$WITHTHECLIENTSREQUESTTHE#ONTAINERNOWKNOWSTHATITMUSTATTEMPTTOSTARTANEWSESSIONWITHTHECLIENT!TTHISPOINTTHE#ONTAINERDOESNTKNOWIFCOOKIESWILLWORKSOWITHTHIS FIRST RESPONSEBACKTOTHECLIENTITTRIES"/4(COOKIES AND 52, REWRITING47HYCANTITTRYCOOKIESlRST AND DO 52, REWRITINGONTHENEXTRESPONSEIFITDOESNTGETBACKACOOKIE$2EMEMBERIFTHE#ONTAINERDOESNTGETASESSION)$FROMTHECLIENTTHE#ONTAINERWONTEVEN+./7THATTHISISTHENEXTREQUESTFROMTHATCLIENT4HE#ONTAINERWONTHAVEANYWAYTOKNOWTHATITTRIEDCOOKIESTHELASTTIME AND THEYDIDNTWORK2EMEMBERTHE/.,9WAYTHE#ONTAINERCANRECOGNIZETHATITHASSEENTHISCLIENTBEFOREISIFTHECLIENTSENDSASESSION)$3OWHENTHE#ONTAINERSEESYOUCALLREQUESTGET3ESSION AND REALIZESITNEEDSTOSTARTANEWSESSIONWITHTHISCLIENTTHE#ONTAINERSENDSTHERESPONSEWITHBOTHAh3ET#OOKIEvHEADERFORTHESESSION)$ AND THESESSION)$APPENDEDTOTHE 52, SASSUMINGYOUUSEDRESPONSEENCODE 52, .OWIMAGINETHENEXTREQUESTFROMTHISCLIENTITWILLHAVETHESESSION)$APPENDEDTOTHEREQUEST 52, BUTIFTHECLIENTACCEPTSCOOKIESTHEREQUESTWILL!,3/HAVEASESSION)$COOKIE7HENTHESERVLETCALLSREQUESTGET3ESSIONTHE#ONTAINERREADSTHESESSION)$FROMTHEREQUESTFINDSTHESESSION AND THINKSTOITSELFh4HISCLIENTACCEPTSCOOKIESSO)CANIGNORETHERESPONSEENCODE 52, CALLS)NTHERESPONSE)LLSENDACOOKIESINCE)KNOWTHATWORKS AND THERESNONEEDFORANY 52, REWRITINGSO)WONTBOTHERv85/UHZULWLQJChapter 6. Conversational stateChapter 6. Conversational state Head First Servlets and JSP By Bert Bates, Kathy Sierra, ... prohibited.VHVVLRQPDQDJHPHQW\RXDUHKHUH'IVENSXEOLFFODVV0\6HUYOHWH[WHQGV+WWS6HUYOHW^SXEOLFYRLGGR*HW+WWS6HUYOHW5HTXHVWUHT+WWS6HUYOHW5HVSRQVHUHVWKURZV ,2( [FHSWLRQ6HUYOHW([FHSWLRQ^UHTXHVWJHW6HVVLRQVHW$WWULEXWH³NH\´³YDOXH´UHTXHVWJHW+WWS6HVVLRQVHW$WWULEXWH³NH\´³YDOXH´+WWS6HVVLRQUHTXHVWJHW6HVVLRQVHW$WWULEXWH³NH\´³YDOXH´+WWS6HVVLRQUHTXHVWJHW+WWS6HVVLRQVHW$WWULEXWH³NH\´³YDOXH´``7HICHLINESCOULDBEUNCOMMENTEDWITHOUTCAUSINGACOMPILEORRUNTIMEERROR#HOOSEALLTHATAPPLYR!,INEONLYR",INEONLYR#,INEONLYR$,INEONLYR%,INEORLINER&,INEORLINE0RFN([DP&KDSWHU)FACLIENTWILL./4ACCEPTACOOKIEWHICHSESSIONMANAGEMENTMECHANISMCOULDTHEWEBCONTAINEREMPLOY#HOOSEONER!#OOKIESBUT./4 52, REWRITINGR" 52, REWRITINGBUT./4COOKIESR#%ITHERCOOKIESOR 52, REWRITINGCANBEUSEDR$.EITHERCOOKIESNOR 52, REWRITINGCANBEUSEDR%#OOKIES AND 52, REWRITINGMUSTBEUSEDTOGETHERChapter...

... prohibited.LQWURDQGDUFKLWHFWXUH\RXDUHKHUH$XVHULVUHWXUQLQJDORJLQQDPHDQGSDVVZRUG$XVHULVUHTXHVWLQJDQHZSDJHYLDDK\SHUOLQN$FKDWURRPXVHULVVHQGLQJDZULWWHQUHVSRQVH$XVHUKLWVWKHµQH[W¶EXWWRQWRVHHWKHQH[WSDJH$XVHUKLWVWKHµORJRXW¶EXWWRQRQDVHFXUHEDQNLQJVLWH$XVHUKLWVWKHµEDFN¶EXWWRQRQWKHEURZVHU$XVHUVHQGVDQDPHDQGDGGUHVVIRUPWRWKHVHUYHU$XVHUPDNHVDUDGLREXWWRQVHOHFWLRQ 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7*(7RU 326 7")RUHDFKGHVFULSWLRQFLUFOHHLWKHU 326 7RU*(7GHSHQGLQJRQZKLFK+773PHWKRG\RX·GFKRRVHIRULPSOHPHQWLQJWKDWIXQFWLRQDOLW\,I\RXWKLQNLWFRXOGEHHLWKHUFLUFOHERWK%XWEHSUHSDUHGWRGHIHQG\RXUDQVZHUV6KDUSHQ ... prohibited.FKDSWHU1N\PI\¼[\PMZM[XWV[M_PI\¼[QV\PMZMY]M[\'4HElRSTTHINGYOULLlNDISAN(440METHODNAME4HESEARENT*AVAMETHODSBUTTHEIDEAISSIMILAR4HEMETHODNAMETELLSTHESERVERTHEKINDOFREQUESTTHATSBEINGMADE AND HOWTHERESTOFTHEMESSAGEWILLBEFORMATTED4HE(440PROTOCOLHASSEVERALMETHODSBUTTHEONESYOULLUSEMOSTOFTENARE'%4 AND 0/34%URZVHU6HUYHUKWPO!KHDG!KHDG!ERG\!ERG\!KWPO!KWPO!KHDG!KHDG!ERG\!ERG\!KWPO!KWPO!KHDG!KHDG!ERG\!ERG\!KWPO!%URZVHUVHQGVDQ+773*(7WRWKHVHUYHUDVNLQJWKHVHUYHUWR*(7WKHSDJH8VHUKWPO!KHDG!KHDG!ERG\!ERG\!KWPO!8VHUFOLFNVDOLQNWRDQHZSDJH%URZVHU6HUYHUKWPO!KHDG!KHDG!ERG\!ERG\!KWPO!KWPO!KHDG!KHDG!ERG\!ERG\!KWPO!KWPO!KHDG!KHDG!ERG\!ERG\!KWPO!%URZVHUVHQGVDQ+773 326 7WRWKHVHUYHUJLYLQJWKHVHUYHUZKDWWKHXVHUW\SHGLQWRWKHIRUP8VHUKWPO!KHDG!KHDG!ERG\!ERG\!KWPO!8VHUW\SHVLQDIRUPDQGKLWVWKH6XEPLWEXWWRQ*(7 326 7*(7 326 7+773PHWKRGVChapter 1. Why use Servlets & JSPs?Chapter 1. Why use Servlets & JSPs? Head First Servlets and JSP By Bert Bates, Kathy Sierra, ... prohibited.LQWURDQGDUFKLWHFWXUH\RXDUHKHUH$XVHULVUHWXUQLQJDORJLQQDPHDQGSDVVZRUG$XVHULVUHTXHVWLQJDQHZSDJHYLDDK\SHUOLQN$FKDWURRPXVHULVVHQGLQJDZULWWHQUHVSRQVH$XVHUKLWVWKHµQH[W¶EXWWRQWRVHHWKHQH[WSDJH$XVHUKLWVWKHµORJRXW¶EXWWRQRQDVHFXUHEDQNLQJVLWH$XVHUKLWVWKHµEDFN¶EXWWRQRQWKHEURZVHU$XVHUVHQGVDQDPHDQGDGGUHVVIRUPWRWKHVHUYHU$XVHUPDNHVDUDGLREXWWRQVHOHFWLRQ 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7 326 7*(7*(7RU 326 7")RUHDFKGHVFULSWLRQFLUFOHHLWKHU 326 7RU*(7GHSHQGLQJRQZKLFK+773PHWKRG\RX·GFKRRVHIRULPSOHPHQWLQJWKDWIXQFWLRQDOLW\,I\RXWKLQNLWFRXOGEHHLWKHUFLUFOHERWK%XWEHSUHSDUHGWRGHIHQG\RXUDQVZHUV6KDUSHQ \RXU SHQFLOChapter 1. Why use Servlets & JSPs?Chapter 1. Why use Servlets & JSPs? Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407...

... 4XHVWLRQV4)SNTTHISOVERKILL)STHISREALLYAPOSSIBILITYTHATACLIENTWILLOPENANOTHERBROWSERWINDOW$/FCOURSEITIS3URELYYOUVEDONETHISYOURSELFWITHOUTASECONDTHOUGHTOPENEDASECONDWINDOWBECAUSEYOUWERETIREDOFWAITINGFORTHEOTHERONETORESPONDORBECAUSEYOUMINIMIZEDONEORMISPLACEDTHEWINDOWWITHOUTREALIZINGITETC4HEPOINTISYOUCANTTAKETHECHANCEIFYOUNEEDTHREADSAFETYFORYOURSESSIONVARIABLES9OUHAVETOKNOWTHATITSQUITEPOSSIBLEFORASESSIONSCOPEDATTRIBUTETOBEUSEDBYMORETHANONETHREADATATIME4)SNTITABADIDEATOSYNCHRONIZECODEBECAUSEITCAUSESALOTOFOVERHEAD AND HURTSCONCURRENCY$9OUSHOULD!,7!93THINKCAREFULLYBEFORESYNCHRONIZINGANYCODEBECAUSEYOURERIGHTITDOESADDSOMEEXPENSEINCHECKINGACQUIRING AND RELEASINGLOCKS)FYOUNEEDPROTECTIONTHENUSESYNCHRONIZATIONBUTREMEMBERTHESTANDARDRULEOFALLFORMSOFLOCKINGKEEPTHELOCKFORTHESHORTESTAMOUNTOFTIMETOACCOMPLISHYOURGOAL)NOTHERWORDSDONTSYNCHRONIZETHECODETHATDOESNTACCESSTHEPROTECTEDSTATE-AKEYOURSYNCHRONIZEDBLOCKASSMALLASPOSSIBLE'ETTHELOCKGETINGETWHATYOUNEED AND GETTHEHECKOUTSOTHELOCKCANRELEASE AND OTHERTHREADSCANRUNTHATCODEV\QFKURQL]HRQWKHVHVVLRQChapter 5. Being a Web AppChapter 5. Being a Web App Head First Servlets and JSP ... automatically.)They use the word ÒboundÓ and ÒunboundÓ to mean Òadded toÓ and Òremoved fromÓ.Chapter 5. Being a Web AppChapter 5. Being a Web App Head First Servlets and JSP By Bert Bates, Kathy Sierra, ... 6WDWLFYDULDEOHVLQWKHVHUYOHW3ODFHDFKHFNPDUNQH[WWRWKHWKLQJVWKDWDUH 127 WKUHDGVDIH:HGLGWKHILUVWRQH<PMM^QT[WN;QVOTM<PZMIL5WLMT!LTHOUGHITSNOTONTHEEXAMBECAUSEITSEVILYOUVEPROBABLYHEARDOFOREVENUSEDTHENOWDEPRECATED3INGLE4HREAD-ODELINTERFACESOWEFEELCOMPELLEDTOMENTIONITWHILESIMULTANEOUSLYREINFORCINGITSEVILNESS4HE3INGLE4HREAD-ODELSOUNDSGOODTONEWBIESATlRSTGLANCEASAWAYTOSOLVEMULTITHREADINGPROBLEMS9OUSIMPLYHAVEYOURSERVLETIMPLEMENTTHE3INGLE4HREAD-ODELINTERFACE AND "//-ASIFBYMAGICYOURSERVLETWILLNEVERHAVEMORETHANONETHREADATATIMERUNNING)NOTHERWORDSYOUVEREDUCEDYOURSERVLETTOASINGLETHREAD'OODBYEMULTITHREADINGPROBLEMSRIGHT.OOFCOURSENOT9OUALREADYKNOWWHYIMPLEMENTING3INGLE4HREAD-ODELISNODIFFERENTTHANSYNCHRONIZINGTHESERVICEMETHODALLYOUVEDONEISDEMOLISHEDYOURCONCURRENCYWITHOUTPROTECTINGATTRIBUTESTATE"ECAUSEAGAINEVENIFALLYOUR SERVLETS IMPLEMENT3INGLE4HREAD-ODELYOUCANSTILLHAVETWO SERVLETS EACHONEDUTIFULLYRUNNINGONLYONECLIENTREQUESTTHREADATATIMEINTHESAMEWEBAPPACCESSINGCONTEXTATTRIBUTESATTHESAMETIME3INGLE4HREAD-ODELOFFERSNOTHINGBUTPOORPERFORMANCEIFYOURAPPLICATIONHASMORETHANONECOMPONENT3INCEITMISLEDTHOUSANDSOFNEWDEVELOPERSINTOTHINKINGTHAT3INGLE4HREAD-ODELGAVETHEMTHREADSAFETYITSBEENDEPRECATED AND THEDEVELOPERSWHOUSEITNOWARESUBJECTTORIDICULE AND HUMILIATION"UTNOWYOUKNOW AND YOUWOULDNEVERHAVEUSEDITANYWAYSINCEYOUALREADYKNOWTHATRESTRICTINGASINGLESERVLETTOASINGLETHREADPROTECTSYOUONLYIFYOURENTIREAPPLICATIONCONSISTSOFASINGLESERVLET3OIFYOUCATCHANYBODYUSING3INGLE4HREAD-ODELREVOKETHEIR3ERVLETLICENSE AND INSISTNODEMANDTHATTHEYBUYACOPYOFTHISBOOK6KDUSHQ \RXU SHQFLOChapter 5. Being a Web AppChapter 5. Being a Web App Head First Servlets and JSP By Bert Bates,...

... µWUXHµDWWULEXWHLQLWVSDJHGLUHFWLYH'HILQHVZKHWKHUWKHFXUUHQWSDJHUHSUHVHQWVDQRWKHU-63·VHUURUSDJH7KHGHIDXOWYDOXHLV´IDOVHµEXWLILW·VWUXHWKHSDJHKDVDFFHVVWRWKHLPSOLFLWH[FHSWLRQREMHFWZKLFKLVDUHIHUHQFHWRWKHRIIHQGLQJ7KURZDEOH,IIDOVHWKHLPSOLFLWH[FHSWLRQREMHFWLVQRWDYDLODEOHWRWKH-63'HILQHVD6WULQJWKDWJHWVSXWLQWRWKHWUDQVODWHGSDJHMXVWVRWKDW\RXFDQJHWLWXVLQJWKHJHQHUDWHGVHUYOHW·VLQKHULWHGJHW6HUYOHW,QIRPHWKRG'HILQHVZKHWKHUWKHJHQHUDWHGVHUYOHWQHHGVWRLPSOHPHQWWKH6LQJOH7KUHDG0RGHOZKLFKDV\RXNQRZLVD6SHFWDFXODUO\%DG7KLQJ7KHGHIDXOWYDOXHLVµWUXHµZKLFKPHDQV´0\DSSLVWKUHDGVDIHVR,GR 127 QHHGWRLPSOHPHQW6LQJOH7KUHDG0RGHOZKLFK,NQRZLVLQKHUHQWO\HYLOµ7KHRQO\UHDVRQWRVSHFLIL\WKLVDWWULEXWHLVLI\RXQHHGWRVHWWKHDWWULEXWHYDOXHWR´IDOVHµZKLFKPHDQVWKDW\RXZDQWWKHJHQHUDWHGVHUYOHWWRXVHWKH6LQJOH7KUHDG0RGHOEXW\RXQHYHUZLOO'HILQHVZKHWKHUWKHEXIIHUHGRXWSXWLVIOXVKHGDXWRPDWLFDOO\7KHGHIDXOWYDOXHLV´WUXHµ'HILQHVKRZEXIIHULQJLVKDQGOHGE\WKHLPSOLFLWRXWREMHFWUHIHUHQFHWRWKH-VS:ULWHU'HILQHVZKHWKHUWKHSDJHZLOOKDYHDQLPSOLFLWVHVVLRQREMHFW7KHGHIDXOWYDOXHLV´WUXHµ'HILQHVWKH-DYDLPSRUWVWDWHPHQWVWKDW·OOEHDGGHGWRWKHJHQHUDWHGVHUYOHWFODVV<RXJHWVRPHLPSRUWVIRUIUHHE\GHIDXOWMDYDODQJGXKMDYD[VHUYOHWMDYD[VHUYOHWKWWSDQGMDYD[VHUYOHWMVS'HILQHVWKHVXSHUFODVVRIWKHFODVVWKLV-63ZLOOEHFRPH<RXZRQ·WXVHWKLVXQOHVV\RX5($//<NQRZZKDW\RX·UHGRLQJ³LWRYHUULGHVWKHFODVVKLHUDUFK\SURYLGHGE\WKH&RQWDLQHU/FTHEPAGEDIRECTIVEATTRIBUTESINTHE*30SPECONLYFOURARECOVEREDONTHEEXAM9OUDO./4HAVETOMEMORIZETHEENTIRELISTJUSTGETAFEELFORWHATYOUCANDO7ELLLOOKATTHEIS%,)GNORED AND THETWOERRORRELATEDATTRIBUTESINLATERCHAPTERS 127 RQWKHH[DP 326 6,%/<RQWKHH[DPChapter 7. Being a JSP Chapter 7. Being a JSP Head First Servlets and JSP By Bert ... 12 does not include a JSP standard action. -Option E is incorrect because the EL in line 11 is valid.PRFNDQVZHUVChapter 7. Being a JSP Chapter 7. Being a JSP Head First Servlets and JSP ... this!,W¶V 127 LQIURQWRIWKHRWKHUWZRPHWKRGVMVS,QLWDQGMVS'HVWUR\7KLQNRILWWKLVZD\WKHXQGHUVFRUHLQIURQWRIWKHPHWKRGPHDQV³GRQ¶WWRXFK´6RQRXQGHUVFRUHLQIURQWRIWKHQDPHPHDQV\RXFDQRYHUULGH%XWLIWKHUH,6DQXQGHUVFRUHLQIURQWRIWKHPHWKRGQDPH\RXPXVW 127 WU\WRRYHUULGHLW1RWHWKHXQGHUVFRUHDWWKHIURQWRIWKHB MVS6HUYLFHPHWKRGChapter 7. Being a JSP Chapter 7. Being a JSP Head First Servlets and JSP By Bert Bates,...

... input from the user and then requests the JSP we were just on Hello .jsp. XVLQJMVSIRUZDUG!Chapter 8. Script-free pagesChapter 8. Script-free pages Head First Servlets and JSP By Bert Bates, ... prohibited.FKDSWHU<PMZMY]M[\;KWXMQ[67<\PMZMY]M[\WJRMK\4HEIMPLICITREQUEST3COPEISJUSTA-APOFTHEREQUESTSCOPEATTRIBUTESNOTTHEREQUESTOBJECTITSELF7HATYOUWANTTHE(440METHODISAPROPERTYOFTHEREQUESTOBJECTNOTANATTRIBUTEATREQUESTSCOPE)NOTHERWORDSYOUWANTSOMETHINGTHATCOMESFROMCALLINGAGETTERMETHODONTHEREQUESTOBJECTIFWETREATTHEREQUESTOBJECTLIKEABEAN"UTTHEREISNOREQUESTIMPLICITOBJECTONLYREQUEST3COPE7HATTODO9OUNEEDSOMETHINGELSE8VHUHTXHVW6FRSHWRJHWUHTXHVW$775,%87(6QRWUHTXHVW3 523 (57,(6)RUUHTXHVWSURSHUWLHV\RXQHHGWRJRWKURXJKSDJH&RQWH[W0HWKRGLV^SDJH&RQWH[WUHTXHVWPHWKRG`8VHSDJH&RQWH[WWRJHWWRHYHU\WKLQJHOVHSDJH&RQWH[WKDVDUHTXHVWSURSHUW\UHTXHVWKDVDPHWKRGSURSHUW\,W¶VVRHDV\WRWKLQNWKDWVD\DSSOLFDWLRQ6FRSHLVDUHIHUHQFHWR6HUYOHW&RQWH[WVLQFHWKDW¶VZKHUHDSSOLFDWLRQVFRSHGDWWULEXWHVDUHERXQG%XWMXVWDVZLWKUHTXHVW6FRSHDQGWKHUHTXHVWREMHFWWKHVFRSH0DSIRUDSSOLFDWLRQVFRSHGDWWULEXWHVLVMXVWWKDW²D0DSRIDWWULEXWHVDQGQRWKLQJPRUH<RXFDQ¶WWUHDWLWOLNHD6HUYOHW&RQWH[WVRGRQ¶WH[SHFWWRJHW6HUYOHW&RQWH[WSURSHUWLHVEDFNIURPWKHDSSOLFDWLRQ6FRSHLPSOLFLWREMHFW'RQ·WFRQIXVHWKH0DSVFRSHREMHFWVZLWKWKHREMHFWVWRZKLFKWKHDWWULEXWHVDUHERXQGVFRSHPDSVDUH 127 WKHUHDOREMHFWChapter 8. Script-free pagesChapter 8. Script-free pages Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ... DSSOLFDWLRQJHW,QLW3DUDPHWHU³PDLQ(PDLO´!$QGZLWK(/LW¶VHYHQHDVLHUHPDLOLV^LQLW3DUDPPDLQ(PDLO`WZRPRUHLPSOLFLWREMHFWV+HUH¶VZKDW¶VFRQIXVLQJVHUYOHWLQLWSDUDPVDUHFRQ¿JXUHGXVLQJLQLWSDUDP!ZKLOHFRQWH[WSDUDPVXVHFRQWH[WSDUDP!EXWWKH(/LPSOLFLW³LQLW3DUDP´LVIRUFRQWH[WSDUDPV+DGWKH\FRQVXOWHGXVZHZRXOGKDYHVXJJHVWHGWKDWWKHVSHFGHVLJQHUVPLJKWFRQVLGHUQDPLQJWKLVYDULDEOHRK³FRQWH[W3DUDP´EXWRQFHDJDLQWKH\IRUJRWWRDVNXV7KH(/LQLW3DUDPLV 127 IRUSDUDPVFRQÀJXUHGXVLQJLQLWSDUDP!Chapter 8. Script-free pagesChapter 8. Script-free pages Head First Servlets and JSP By Bert Bates, Kathy Sierra,...

... fragment and NOT a complete page with opening and closing <html><body> tags.)Chapter 9. Custom tags are powerfulChapter 9. Custom tags are powerful Head First Servlets and JSP By ... available to the header JSP by setting it as a new request parameter.WKHFLPSRUW!WDJChapter 9. Custom tags are powerfulChapter 9. Custom tags are powerful Head First Servlets and JSP By Bert ... can have anything that can go inside a JSP. WDJERGLHVChapter 9. Custom tags are powerfulChapter 9. Custom tags are powerful Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham...

... 2- 27)7HICHAREVALIDMETHODCALLSONA3DJH&RQWH[WOBJECT#HOOSEALLTHATAPPLYR!JHW$WWULEXWH1DPHVR"JHW$WWULEXWH³NH\´R#¿QG$WWULEXWH³NH\´R$JHW6HVVLRQ$WWULEXWHR%JHW$WWULEXWHV6FRSH³NH\´R&¿QG$WWULEXWH³NH\´3DJH&RQWH[W6(66 ,21 B6& ;23 (R'JHW$WWULEXWH³NH\´3DJH&RQWH[W6(66 ,21 B6& ;23 (-Options A and D are invalid because there are no methods with these names. (JSP v2.0 pg. 2- 23)-Option ... prohibited.FXVWRPWDJGHYHORSPHQW\RXDUHKHUH7HICHABOUTGR$IWHU%RG\ISTRUE#HOOSEALLTHATAPPLYR!GR$IWHU%RG\ISONLYCALLEDONTAGSTHATEXTEND7DJ6XSSRUWR"GR$IWHU%RG\ISONLYCALLEDONTAGSTHATEXTEND,WHUDWLRQ7DJ6XSSRUWR#!SSUMINGNOEXCEPTIONSOCCURGR$IWHU%RG\ISALWAYSCALLEDAFTERGR6WDUW7DJFORANYTAGTHATIMPLEMENTS,WHUDWLRQ7DJR$!SSUMINGNOEXCEPTIONSOCCURGR$IWHU%RG\ISCALLEDAFTERGR6WDUW7DJFORANYTAGTHATIMPLEMENTS,WHUDWLRQ7DJ AND RETURNS6.,3B %2& apos;<FROMGR6WDUW7DJR%!SSUMINGNOEXCEPTIONSOCCURGR$IWHU%RG\ISCALLEDAFTERGR6WDUW7DJFORANYTAGTHATIMPLEMENTS,WHUDWLRQ7DJ AND RETURNS(9$/B %2& apos;<B,1&/8'(FROMGR6WDUW7DJ'IVENSXEOLFFODVV%XI7DJH[WHQGV%RG\7DJ6XSSRUW^SXEOLFLQWGR6WDUW7DJWKURZV-VS([FHSWLRQ^LQVHUWFRGHKHUH``!SSUMETHATTHETAGHASBEENPROPERLYCONlGUREDTOALLOWBODYCONTENT7HICHIFINSERTEDATLINEWOULDCAUSETHE*30CODEP\WDJVP\WDJ!%RG\&RQWHQWP\WDJVP\WDJ!TOOUTPUT%RG\&RQWHQWR!UHWXUQ6.,3B %2& apos;<R"UHWXUQ(9$/B %2& apos;<B,1&/8'(R#UHWXUQ(9$/B %2& apos;<B%8))(5('R$UHWXUQ %2& apos;<B& ;21 7(17 (JSP v2.0 pg. 2- 68)-Option ... prohibited.FXVWRPWDJGHYHORSPHQW\RXDUHKHUH=[QVO\PM8IOM+WV\M`\)81NWZ\IOPIVLTMZ[4HISPAGEISJUSTAREVIEWFROMWHATYOUSAWINTHE3CRIPTFREE*30SCHAPTERBUTITCOMESUPAGAINHEREBECAUSEITSCRUCIALFORATAGHANDLER!TAGHANDLERCLASSREMEMBERISNOTASERVLETORA*30SOITDOESNTHAVEAUTOMATICACCESSTOABUNCHOFIMPLICITOBJECTS"UTITDOESGETAREFERENCETOA0AGE#ONTEXT AND WITHITITCANGETTOALLKINDSOFTHINGSITMIGHTNEED2EMEMBERTHATWHILE3IMPLETAGSGETAREFERENCETOA*SP#ONTEXT AND #LASSICTAGSGETAREFERENCETOA0AGE#ONTEXTTHE3IMPLETAGS*SP#ONTEXTISUSUALLYA0AGE#ONTEXTINSTANCE3OIFYOUR3IMPLETAGHANDLERNEEDSACCESSTO0AGE#ONTEXTSPECIlCMETHODSORlELDSYOULLHAVETOCASTITFROMA*SP#ONTEXTTOTHE0AGE#ONTEXTITREALLYISONTHEHEAPJHW$WWULEXWH6WULQJQDPHJHW$WWULEXWH6WULQJQDPHLQWVFRSHJHW$WWULEXWH1DPHV,Q6FRSHLQWVFRSHILQG$WWULEXWH6WULQJQDPHJHW2XWPRUHPHWKRGVLQFOXGLQJVLPLODUPHWKRGVWRVHWDQGUHPRYHDWWULEXWHVIURPDQ\VFRSH-VS&RQWH[W$33/,&$7 ,21 B6& ;23 (3$*(B6& ;23 (5(48(67B6& ;23 (6(66 ,21 B6& ;23 (PRUHILHOGVJHW5HTXHVWJHW6HUYOHW&RQILJJHW6HUYOHW&RQWH[WJHW6HVVLRQPRUHPHWKRGV3DJH&RQWH[Wstatic...

... prohibited.WKLVLVDQHZFKDSWHU<RXUZHEDSSLVLQGDQJHU7URXEOHOXUNVLQHYHU\FRUQHURIWKHQHWZRUNDVFUDFNHUVVFDPPHUVDQGFULPLQDOVWU\WREUHDNLQWR\RXUV\VWHPWRVWHDOWDNHDGYDQWDJHRUMXVWKDYHDOLWWOHIXQZLWK\RXUVLWH<RXGRQ¶WZDQWWKH%DG*X\VOLVWHQLQJLQWR\RXURQOLQHVWRUHWUDQVDFWLRQVSLFNLQJRIIFUHGLWFDUGQXPEHUV<RXGRQ¶WZDQWWKH%DG*X\VFRQYLQFLQJ\RXUVHUYHUWKDWWKH\¶UHDFWXDOO\WKH6SHFLDO&XVWRPHUV:KR*HW%LJ'LVFRXQWV$QG\RXGRQ¶WZDQWDQ\RQHJRRG 25 EDGORRNLQJDWVHQVLWLYHHPSOR\HHGDWD'RHV-LPLQPDUNHWLQJUHDOO\QHHGWRNQRZWKDW/LVDLQHQJLQHHULQJPDNHVWKUHHWLPHVDVPXFKDVKHGRHV"$QGGR\RXUHDOO\ZDQW-LPWRWDNHPDWWHUVLQWRKLVRZQKDQGVDQGORJLQXQDXWKRUL]HGWRWKH8SGDWH3D\UROOVHUYOHW".HHSLWVHFUHWNHHSLWVDIHZHEDSSVHFXULW\7KH\·UHRXWWKHUH7KH%DG*X\VWKH\·UHHYHU\ZKHUH,PXVWOHDUQDERXW$XWKHQWLFDWLRQDQG$XWKRUL]DWLRQ,PXVWOHDUQWRWUDQVPLWWKHGDWDVHFXUHO\,,','< ;28 +($57+$7"Chapter 12. Keep it secret, keep it safeChapter 12. Keep it secret, keep it safe Head First Servlets and JSP By Bert Bates, Kathy Sierra, ... WR¶8SGDWH5HFLSHV·$%(YHU\ERG\,]MTQVO$I]\PKWV[\ZIQV\&MTMUMV\[)FTWOORMORESECURITYCONSTRAINTELEMENTSHAVEPARTIALLYORFULLYOVERLAPPINGWEBRESOURCECOLLECTIONELEMENTSHERESHOWTHECONTAINERRESOLVESACCESSTOTHEOVERLAPPINGRESOURCES! AND "REFERTOTHE$$ONTHEPREVIOUSPAGE5XOHVIRULQWHUSUHWLQJWKLVWDEOH:KHQFRPELQLQJLQGLYLGXDOUROHQDPHVDOORIWKHUROHQDPHVOLVWHGZLOOEHDOORZHG$UROHQDPHRI´´FRPELQHVZLWKDQ\WKLQJHOVHWRDOORZDFFHVVWRHYHU\ERG\$QHPSW\DXWKFRQVWUDLQW!WDJFRPELQHVZLWKDQ\WKLQJHOVHWRDOORZDFFHVVWRQRERG\,QRWKHUZRUGVDQHPSW\DXWKFRQVWUDLQW!LVDOZD\VWKHILQDOZRUG,IRQHRIWKHVHFXULW\FRQVWUDLQW!HOHPHQWVKDVQRDXWKFRQVWUDLQW!HOHPHQWLWFRPELQHVZLWKDQ\WKLQJHOVHWRDOORZDFFHVVWRHYHU\ERG\*XHVWVDQG$GPLQVDXWKFRQVWUDLQW!UROHQDPH!*XHVWUROHQDPH!DXWKFRQVWUDLQW!DXWKFRQVWUDLQW!UROHQDPH!$GPLQUROHQDPH!DXWKFRQVWUDLQW!(YHU\ERG\1RERG\DXWKFRQVWUDLQW!UROHQDPH!*XHVWUROHQDPH!DXWKFRQVWUDLQW!DXWKFRQVWUDLQW!DXWKFRQVWUDLQW!UROHQDPH!UROHQDPH!DXWKFRQVWUDLQW!DXWKFRQVWUDLQW!UROHQDPH!$GPLQUROHQDPH!DXWKFRQVWUDLQW!DXWKFRQVWUDLQW!UROHQDPH!$GPLQUROHQDPH!DXWKFRQVWUDLQW!:KHQWZRGLIIHUHQWQRQHPSW\DXWKFRQVWUDLQW!HOHPHQWVDSSO\WRWKHVDPHFRQVWUDLQHGUHVRXUFHDFFHVVLVJUDQWHGWRWKHXQLRQRIDOOUROHVIURPERWKRIWKHDXWKFRQVWUDLQW!HOHPHQWV 12 DXWKFRQVWUDLQW!HOHPHQWempty tagChapter 12. Keep it secret, keep it safeChapter 12. Keep it secret, keep it safe Head First Servlets and JSP By Bert Bates, Kathy ... prohibited.ZHEDSSVHFXULW\\RXDUHKHUH)]\PMV\QKI\QWVZM^Q[Q\ML&ORA*%%#ONTAINERAUTHENTICATIONCOMESDOWNTOTHISASKFORAUSERNAME AND PASSWORDTHENVERIFYTHATTHEYMATCH4HElRSTTIMEANUNAUTHENTICATEDUSERASKSFORACONSTRAINEDRESOURCETHE#ONTAINERWILLAUTOMATICALLYSTARTTHEAUTHENTICATIONPROCESS4HEREAREFOURTYPESOFAUTHENTICATIONTHE#ONTAINERCANPROVIDE AND THEMAINDIFFERENCEBETWEENTHEMISh(OWSECURELYISTHENAME AND PASSWORDINFOTRANSMITTEDv7KH )28 5DXWKHQWLFDWLRQW\SHV 2. VR,NQRZDOODERXWDXWKRUL]DWLRQEXW,VWLOOGRQ·WNQRZKRZDXWKHQWLFDWLRQKDSSHQVRUH[DFWO\ZKDW,KDYHWRGRWRPDNHWKH&RQWDLQHUDVNIRUDQDPHDQGSDVVZRUG"!3)#AUTHENTICATIONTRANSMITSTHELOGININFORMATIONINANENCODEDNOTENCRYPTEDFORM4HATMIGHTSOUNDSECUREBUTYOUPROBABLYALREADYKNOWTHATSINCETHEENCODINGSCHEMEBASEISREALLYWELLKNOWN"!3)#PROVIDESVERYWEAKSECURITY$)'%34AUTHENTICATIONTRANSMITSTHELOGININFORMATIONINAMORESECUREWAYBUTBECAUSETHEENCRYPTIONMECHANISMISNTWIDELYUSED*%%CONTAINERSARENTREQUIREDTOSUPPORTIT&ORMOREINFOON$)'%34AUTHENTICATIONCHECKOUTTHE)%4& 2& amp;#WWWIETFORGRFCRFCTXT#,)%.4# %24 AUTHENTICATIONTRANSMITSTHELOGININFORMATIONINANEXTREMELYSECUREFORMUSING0UBLIC+EY#ERTIlCATES0+#4HEDOWNSIDETOTHISMECHANISMISTHATYOURCLIENTSNEEDTOHAVEACERTIlCATEBEFORETHEYCANLOGINTOYOURSYSTEM)TSFAIRLYRAREFORCONSUMERSTOHAVEACERTIlCATESO#,)%.4# %24 AUTHENTICATIONISUSEDMAINLYINBUSINESSTOBUSINESSSCENARIOS4HETHREETYPESABOVE"!3)#$)'%34 AND #,)%.4# %24 ALLUSETHEBROWSERSSTANDARDPOPUPFORMFORINPUTTINGTHENAME AND PASSWORD"UTTHEFOURTHTYPE& /2- ISDIFFERENT& /2- AUTHENTICATIONLETSYOUCREATEYOUROWNCUSTOMLOGINFORMOUTOFANYTHINGTHATSLEGAL(4-,"UTOFALLFOURTYPESTHEFORMBASEDINFOISTRANSMITTEDINTHELEASTSECUREWAY4HEUSERNAME AND PASSWORDARESENTBACKINTHE(440REQUESTWITHNOENCRYPTIONChapter 12. Keep it secret, keep it safeChapter 12. Keep it secret, keep it safe Head First Servlets and JSP By Bert...

... prohibited.FKDSWHUFODVV*=,36HUYOHW2XWSXW6WUHDPH[WHQGV6HUYOHW2XWSXW6WUHDP^*=,32XWSXW6WUHDPLQWHUQDO*]LS26'HFRUDWRUFRQVWUXFWRU*=,36HUYOHW2XWSXW6WUHDP6HUYOHW2XWSXW6WUHDPVRVWKURZV ,2( [FHSWLRQ^WKLVLQWHUQDO*]LS26 ... prohibited.FKDSWHU7KLVZRQ·WZRUN,FDQ·WFRPSUHVVVRPHWKLQJRQWKHZD\RXWRIWKHVHUYOHWEHFDXVHLW·VWRRODWH7KHRXWSXWJRHVVWUDLJKWIURPWKHVHUYOHWEDFNWRWKHFOLHQW%XWWKHZKROHSRLQWLVWRFRPSUHVVWKHRXWSXWVRKRZFDQ,JHWFRQWURORIWKHRXWSXW%( )25 (LWJRHVWRWKHFOLHQW"<PMW]\X]\PI[TMN\\PMJ]QTLQVO7KLQNDERXWWKLVIRUDPLQXWHWKHVHUYOHWDFWXDOO\JHWVWKHRXWSXWVWUHDPRUZULWHUIURPWKHUHVSRQVHREMHFW:KDWLILQVWHDGRISDVVLQJWKH5($/UHVSRQVHREMHFWWRWKHVHUYOHW\RXUÀOWHUVZDSSHGLQDFXVWRPUHVSRQVHREMHFWZLWKDQRXWSXWVWUHDPWKDW\RXFRQWURO"1RERG\VDLGWKHÀOWHUKDVWRSDVVWKH5($/UHVSRQVHZKHQLWFDOOVFKDLQGR)LOWHUFKDLQGR)LOWHU&RQWDLQHUGR)LOWHUOriginal request and responseA DIFFERENT response)LOWHU6HUYOHW¿OWHULQJWKHRXWSXWChapter 13. The Power of FiltersChapter 13. The Power of Filters Head First Servlets and JSP By Bert Bates, ... from both it and its superinterface ServletResponse. LPSOHPHQWLQJ+WWS6HUYOHW5HVSRQVHChapter 13. The Power of FiltersChapter 13. The Power of Filters Head First Servlets and JSP By Bert Bates,...