JSP技术 ---外文文献.docx

JSP技术 ---外文文献.docx

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外文文献

JSPTechnologyandServlets

JSPprofile

JSP（JavaServerPages）isinitiatedbySunMicrosystems,Inc.,withmanycompaniestoparticipateintheestablishmentofadynamicwebpagetechnicalstandards.JSPtechnologysomewhatsimilartoASPtechnology,itisinthetraditionalHTMLwebpagedocument（*・htm,*.html）toinserttheJavaprogrammingparagraph（Scriptiet）andJSPtag（tag）,thusJSPdocuments（*.jsp）.UsingJSPdevelopmentoftheWebapplicationiscrossthatcanrunonLinux,isalsoavailableforotheroperatingsystems.

JSPtechnologytousetheJavaprogramminglanguagepreparedbythecategoryofXMLtagsandscriptlets,toproducedynamicpagespackageprocessinglogic.Pagealsovisitbytagsandsciptletsexistintheservicessideoftheresourcesoflogic.JSPpagelogicandwebpagedesignanddisplayseparation,supportreusablecomponent-baseddesign,Web-basedapplicationdevelopmentisrapidandeasy.

WebserverinthefaceofvisitsJSPpagerequest,thefirstinpiementationoftheproceduresof,andthentogetherwiththeresultsoftheimplementationofJSPdocumentsinHTMLcodewiththereturntothecustomer.InserttheJavaprogrammingoperationofthedatabasecanbereorientedwebsites,inordertoachievetheestablishmentofdynamicpagesneededtofunction.JSPandJavaServlet,isintheimplementationoftheserver,usuallyreturnedtotheclientisanHTMLtext,aslongastheclientbrowserwillbeabletovisit.

JSP1.0specificationofthefinalversionislaunchedinSeptember1999,Decemberhasintroduced1.1specifications.AtpresentrelativelynewisJSP1.2norms,JSP2.0normsofthedrafthasalsobeenintroduced.JSPpagesfromHTMLcodeandJavacodeembeddedinoneoftheconq）onents.

JSscriptlanguagesynopsis

JSisjavascrip,JavascriptisonekindthesciptlanguagewhichcomesbytheNetscapeLiveScrq）tdevelopment,themainpurposeistosolvetheserverterminallanguage,forinstancePerl,carry-overspeedquestion.Atthattimeservedtheendtoneedtocarryontheconfirmationtothedata,becausethenetworkspeedwasquiteslow,onlythen28.8kbps?

theconfirmationstepwaste'stimeweretoomany.ThereforeNetscapebrowserNavigatorhasjoinedJavascipt,hasprovidedthedataconfirmationbasicfunction.

TheJavaScriptofficialnameis"ECMAScript".ThisstandardbyECMAorganizationdevelopmentandmaintenance.ECMA262istheofficialJavaSciptstandard.ThisstandardbasedonJavaScript（Netscape）andJScipt（Microsoft）.Netscape（Navigator2.0）BrendanEichhasinventedthislanguage,startedfrom1996,alreadyappearedinallNetscapeandintheMicrosoftbrowser.TheECMA262developmentbeganin1996,in1997July,theECMAgeneralmeetinghasaccq）teditsfirstedition.

Thesciptusesonespecificdescriptivelanguage,restsoncertainformcompilationtobepossibletheexecutiondocument,isalsocalledasgreatorthebatchrundocument.Thesciptusuallymaytransfertemporarilybytheapplicationprocedureandcarryout.Eachkindofsciptpresentwidelyisappliedinthehomepagedesign,becausethesciptnotonlymayreducethehomepagethescaleandraisesthehomepagebrowsingspeed,moreovermayenrichthehomepageperformance,likeanimation,soundandsoon.Citesamostcommonexample,whenweclickinthehomepagetheEmailaddresscantransferOutlookExpressortheFoxmailthiskindofmailsoftwareautomatically,isrealizesthroughthesciptfunction.Alsobecauseofscriptthesecharacteristics,thehumanwhoharborsulteriormotivesbysomeareoftenusing.Forexamplejoinssomedestructioncomputersystem'sorderinthescript,likethisworksastheuserbrowsinghomepage,oncetransfersthiskindofscript,willthencausetheuserthesystemtocomeundertheattack.Thereforetheusershouldactaccordingtovisitshomepagethetrustdegreeselectivesecurityrank,speciallyregardingtheseitselfcontentontheillegalhomepage,donotpermittheusescripteasily.Through"thesafeestablishment95thedialogbox,thechoice"thescript”imderoptioneachkindofestablishmentmaywitheaserealizetosciptbeingforbidandbeginsusing.

JSPandServlets

ThetechnologyofJSPandServletisthemostimportanttechnologywhichuseJava

technologytoexploitrequestofserver,anditisalsothestandardwhichexploitbusinessapplication.Javadevelopersprefertouseitforavarietyofreasons,oneofwhichisalreadyfamiliarwiththeJavalanguageforthedevelopmentofthistechnologyareeasytolearnJavatotheotherisnapreparation,runeverywhere"tobringtheconceptofWebapplications,Toachievea“one-preparedeverywhererealized.nAndmoreimportantly,iffollowedsomeoftheprinc»lesofgooddesign,itcanbesaidofsq）aratingandcontenttocreatehigh-quality,reusable,easytomaintainandmodifytheapplication.Forexanple,ifthedocumentinHTMLembeddedJavacodetoomuch（scipt）,willleadthedevelopedapplicationisextremelyconplex,difficulttoread,itisnoteasyreuse,butalsoforfuturemaintenanceandmodificationwillalsocausedifficulties.Infact,CSDNtheJSP/Servletforum,canoftenseesomequestions,thecodeisverylong,canlogicisnotveryclear,alargenumberofHTMLandJavacodemixedtogether.Thisistherandomdevelopmentofthedefects.

EarlydynamicpagesmainlyCGI（CommonGatewayInterface,publicGatewayInterface）technology,youcanusedifferentlanguagesoftheCGIprograms,suehasVB,C/C++orDelphi,andsoon.ThoughthetechnologyofCGIisdevelopedandpowerful,becauseofdifficultiesinprogramming,andlowefficiency,modifycorrplexshortcomings,itisgraduallybeingreplacedbythetrend.Ofallthenewtechnology,JSP/Servletwithmoreefficientandeasytoprogram,morepowerful,moresecureandhasagoodportability,theyhavebeenmanypeoplebelievethatthefutureisthemostdynamicsiteofthefuturedevelopmentoftechnology.

SimilartoCGI,Servletsupportrequest/responsemodelWhenacustomersubmitarequesttotheserver,theserverpresentedtherequestServlet,Servletresponsibleforhandlingrequestsandgeneratearesponse,andthengavetheserver,andthenfromtheserversenttothecustomer.AndtheCGIisdifferent,Servletnotgenerateanewprocess,butwithHTTPServeratthesameprocess.Itthreadsthroughtheuseoftechnology,reducetheservercosts.Servlethandlingoftherequestprocessisthis:

Whenreceivedfromtheclient'srequest,callingservicemethods,themethodofServletarrivalofthefirstjudgementiswhattypeofrequest（GET/POST/HEAD...）,thencallstheappropriatetreatment（DoGet/doPost/doHead...）andgeneratearesponse.

Althoughsuchacomplex,infact,simplysaidtoServletisaJavaclass.AndthegeneralcategoryofthedifferenceisthatthistypeoperatinginaServletcontainer,whichcanprovidesessionmanagementandtargetedlifecyclemanagement.SothatwhenyouusetheServlet,youcangetallthebenefitsoftheJavaplatform,includingthesafetyofthemanagement,useJDBCaccessthedatabaseandcrossplatfbrmcapability.Moreover,Servletusingthread,andcandevelopmoreefficientWebapplications.

JSPtechnologyisakeyJ2EEtechnology,itatahigherlevelofabstractionofaServlet.ItallowsconventionalstaticanddynamicHTMLcontentgeneratedbycombininganHTMLpagelookslike,butasaServlettorun.TherearemanycommercialapplicationserversupportJSPtechnology,suchasBEAWd?

Logic,IBMWebSphere,JRun,andsoon.JSPandServletusemorethansingle.IfyouhaveaJSPsupportforWebservers,andaJSPdocument,youcanputitFangdaoanystaticHTMLfilescanbeplaced,donothavetocompile,donothavetopack,donothavetoClassPathsettings,youcanvisitasordinaryWebItdidvisit,theserverwillautomaticallyhe字youtodootherwork.

JSPdocumentlookslikeanordinarystaticHTMLdocument,butinsidecontainsanumberofJavacode.Ituses.Jspthesuffix,usedtotelltheserverthisdocumentinneedofspecialtreatment.WhenwevisitaJSPpage,thedocumentwillfirstbetranslatedintoaJSPengineJavasourcefiles,isactuallyaServlet,andcompiler,andthen,likeotherServlet,fromServletenginetohandle.Servletengineofthistypeloading,handlingrequestsfromcustomers,andtheresultsreturnedtothecustomer.

Afteranothervisitthispagetothecustomer,aslongasthepapertherehavebeennochanges,JSPenginehasbeenloadeddirectlycalltheServletIfyouhavealreadybeenmodified,itwillbeonceagaintheimplementationoftheaboveprocess,translate,conpileandload.Infact,thisistheso-callednfirstpersontopunishment.”Becausewhenthefirstvisittotheimplementationofaseriesoftheaboveprocess,sowillspendsometimeaftersuchavisitwouldnot.

JavaservletsofferapowerfulAPIthatprovidesaccesstoalltheinformationabouttherequest,thesession,andtheapplication,combiningJSPwithservletsletsyouclearlyseparatetheapplicationlogicfromthepresentationoftheapplication;inotherwords,itletsyouusethemostappropriatecomponenttypefortherolesofModel,ViewandController.

Servlets,Filters,andListeners

AservletisaJavaclassthatextendsaserverwithfunctionalityforprocessingarequestandproducingaresponse.IfsimplementedusingtheclassesandinterfacesdefinedbytheServletAPI.TheAPIconsistsoftwopackages:

thejavax.servletpackagecontainsclassesandinterfacesthatareprotocolindependent,whilethejavax.servlet.httppackageprovidesHTTP-specificextensionsandutilityclasses.

Whatmakesaservletaservletisthattheclassimplementsaninterfacenamedjavax.servlet.Servlet,eitherdir