外文翻译--JSP技术发展史.doc

ThetechniquedevelopmenthistoryofJSPTheJavaServerPagesJSPisakindofaccordingtowebofthescriptplaitdistancetechnique,similarcarriesthescriptlanguageofJavaintheserveroftheNetscapecompanyofserversideJavaScriptSSJSandtheActiveServerPagesASPoftheMicrosoft.JSPcomparestheSSJSandASPtohavebettercanexpandsex,anditisnomoreexclusivethananyfactoryorsomeoneparticularserverofWeb.ThoughthenormofJSPistobedrawupbytheSuncompanyof,anyfactorycancarryouttheJSPonownsystem.TheAfterSunreleasetheJSPtheJavaServerPagesformally,thethiskindofnewWebapplicationdevelopmenttechniqueveryquicklycausedthepeoplesconcern.JSPprovidedaspecialdevelopmentenvironmentfortheWebapplicationthatestablishesthehighdynamicstate.AccordingtotheSunparlance,theJSPcanadapttoincludetheApacheWebServer,IIS4.0onthemarketatinsideof85serverproduct.ThischapterwillintroducetherelatedknowledgeofJSPandDatabases,andJavaBeanrelatedcontents,isallcertainlyrougherintroductionamongthembasiccontents,sayperhapstoisaGuideonly,ifthereaderneedsthemoredetailedinformation,pleasingthebookofconsultthehomologousJSP.A.GeneralizeTheJSPJavaServerPagesisfromthecompanyofSunMicrosystemsinitiate,themanycompaniestheparticipatetothebuildupthetogetheroftheakindtheofdynamicthestatewebthepagetechniquestandard,theithavetheitintheconstructiontheofthedynamicstatethewebpagethestrongbutthedonottheespeciallyofthefunction.JSPandthetechniqueofASPoftheMicrosoftisveryalike.BothallprovidetheabilitythatmixeswithacertainprocedurecodeandisexplainbythelanguageenginetocarryouttheprocedurecodeinthecodeofHTML.Underneathwearesimpleofcarryontheintroductiontoit.JSPpagesaretranslatedintoservlets.So,fundamentally,anytaskJSPpagescanperformcouldalsobeaccomplishedbyservlets.However,thisunderlyingequivalencedoesnotmeanthatservletsandJSPpagesareequallyappropriateinallscenarios.Theissueisnotthepowerofthetechnology,itistheconvenience,productivity,andmaintainabilityofoneortheother.Afterall,anythingyoucandoonaparticularcomputerplatformintheJavaprogramminglanguageyoucouldalsodoinassemblylanguage.Butitstillmatterswhichyouchoose.JSPprovidesthefollowingbenefitsoverservletsaloneItiseasiertowriteandmaintaintheHTML.YourstaticcodeisordinaryHTMLnoextrabackslashes,nodoublequotes,andnolurkingJavasyntax.YoucanusestandardWebsitedevelopmenttools.EvenHTMLtoolsthatknownothingaboutJSPcanbeusedbecausetheysimplyignoretheJSPtags.Youcandivideupyourdevelopmentteam.TheJavaprogrammerscanworkonthedynamiccode.TheWebdeveloperscanconcentrateonthepresentationlayer.Onlargeprojects,thisdivisionisveryimportant.Dependingonthesizeofyourteamandthecomplexityofyourproject,youcanenforceaweakerorstrongerseparationbetweenthestaticHTMLandthedynamiccontent.Now,thisdiscussionisnottosaythatyoushouldstopusingservletsanduseonlyJSPinstead.Bynomeans.Almostallprojectswilluseboth.Forsomerequestsinyourproject,youwilluseservlets.Forothers,youwilluseJSP.Forstillothers,youwillcombinethemwiththeMVCarchitecture.Youwanttheappropriatetoolforthejob,andservlets,bythemselves,donotcompleteyourtoolkit.B.SourceofJSPThetechniqueofJSPofthecompanyofSun,makingthepageofWebdevelopthepersonnelcanusetheHTMLperhapsmarkingofXMLtodesigntoturntheendpagewithformat.UsetheperhapssmallscriptfuturelifeofmarkingofJSPbecomesthedynamicstateonthepagecontents.thecontentschangesaccordingtotheclaimofTheJavaServletisatechnicalfoundationofJSP,andthelargeWebappliesthedevelopmentoftheproceduretoneedtheJavaServlettomatchwithwiththeJSPandthencancomplete,thisnameofServletcomesfromtheApplet,thelocaltranslationmethodofnowisalotof,thisbookinordernottomisconstruction,decidethedirectadoptionServletbutdontdoanytranslation,ifreaderwouldliketo,cancallitassmallserviceprocedure.TheServletissimilartotraditionalCGI,ISAPI,NSAPIetc.Webproceduredevelopmentthefunctionofthetoolinfact,atusetheJavaServlethereafter,thecustomerneednotuseagainthelowlymethodofCGIofefficiency,alsoneednotuseonlytheabilitycometobornpageofWebofdynamicstateinthemethodofAPIthatacertainfixedWebserverterracecirculate.ManyserversofWeballsupporttheServlet,evennotsupporttheServletserverofWebdirectlyandcanalsopasstheadditionalappliedserverandthemoldpiecestosupporttheServlet.ReceivebenefitinthecharacteristicoftheJavacrossplatform,theServletisalsoaterraceirrelevant,actually,aslongasmatchthenormofJavaServlet,theServletiscompletetohavenothingtodowithterraceandistohavenothingtodowithserverofWeb.BecausetheJavaServletisinternaltoprovidetheservicebythelinedistance,neednotstartaprogresstotheeachclaimses,andmakeuseofthemultithreadingmechanismcanatthesametimeforseveralclaimservice,thereforetheefficiencyofJavaServletisveryhigh.ButtheJavaServletalsoisnottohasnoweakness,similartotraditionalCGI,ISAPI,theNSAPImethod,theJavaServletistomakeuseoftooutputtheHTMLlanguagesentencetocarryoutthedynamicstatewebpageof,ifdevelopthewholewebsitewiththeJavaServlet,theintegrationprocessofthedynamicstatepartandthestaticstatepageisanevilforebodingdreamsimply.ForsolvingthiskindofweaknessoftheJavaServlet,theSUNreleasedtheJSP.Anumberofyearsago,Martywasinvitedtoattendasmall20personindustryroundtablediscussiononsoftwaretechnology.SittingintheseatnexttoMartywasJamesGosling,inventoroftheJavaprogramminglanguage.SittingseveralseatsawaywasahighlevelmanagerfromaverylargesoftwarecompanyinRedmond,Washington.Duringthediscussion,themoderatorbroughtupthesubjectofJini,whichatthattimewasanewJavatechnology.Themoderatoraskedthemanagerwhathethoughtofit,andthemanagerrespondedthatitwastooearlytotell,butthatitseemedtobeanexcellentidea.Hewentontosaythattheywouldkeepaneyeonit,andifitseemedtobecatchingon,theywouldfollowhiscompanysusualembraceandextendstrategy.Atthispoint,GoslinglightheartedlyinterjectedYoumeandisgraceanddistend.Now,thegrievancethatGoslingwasairingwasthathefeltthatthiscompanywouldtaketechnologyfromothercompaniesandsubornitfortheirownpurposes.ButguesswhatTheshoeisontheotherfoothere.TheJavacommunitydidnotinventtheideaofdesigningpagesasamixtureofstaticHTMLanddynamiccodemarkedwithspecialtags.Forexample,ColdFusiondidityearsearlier.EvenASPaproductfromtheverysoftwarecompanyoftheaforementionedmanagerpopularizedthisapproachbeforeJSPcamealonganddecidedtojumponthebandwagon.Infact,JSPnotonlyadoptedthegeneralidea,itevenusedmanyofthesamespecialtagsasASPdid.TheJSPisanestablishmentatthemodelofJavaservletsonoftheexpressionlayertechnique,itmakestheplaitwritetheHTMLtobecomemoresimple.BeliketheSSJS,italsoallowsyoucarrythestaticstateHTMLcontentsandserversthescriptmixtoputtogethertheborndynamicstateexportation.JSPthescriptlanguagethattheJavaisthetacitapproval,however,beliketheASPandcanuseotherlanguagessuchasJavaScriptandVBScript,thenormofJSPalsoallowstouseotherlanguages.C.JSPcharacteristicsIsaserviceaccordingtothescriptlanguageinsomeonelanguageofthestaturessystemthiskindofdiscuss,theJSPshouldbeseemakeisakindofscriptlanguage.However,beakindofscriptlanguage,theJSPseemedtobetoostrongagain,almostcanuseallJavasintheJSP.Beakindofaccordingtotextoriginallyof,takemanifestationasthecentraldevelopmenttechnique,theJSPprovidedalladvantagesoftheJavaServlet,and,whencombinewithaJavaBeanstogether,providingakindofmakecontentsandmanifestationthatsimplewaythatlogicseparate.Separatethecontentsandadvantageoflogicalmanifestationsis,thepersonnelwhorenewsthepageexternalappearanceneednotknowthecodeofJava,andrenewtheJavaBeanspersonnelalsoneednotbedesignthewebpageofexpertinhand,canusetotakethepageofJavaBeansJSPtodefinethetemplateofWeb,tobuildupafromhavethealikeexternalappearanceofthewebsitethatpageconstitute.JavaBeanscompletesthedatatoprovide,havingnocodeofJavainthetemplatethus,thismeansthatthesetemplatescanbewrittenthepersonnelbyaHTMLplaittosupport.Certainly,canalsomakeuseoftheJavaServlettocontrolthelogicofthewebsite,adjustthroughtheJavaServlettousethewayofthedocumentofJSPtoseparatewebsiteoflogicandcontents.Generallyspeaking,inactualengineofJSP,thepageofJSPistheeditandtranslatetypewhilecarryout,notexplainthetypeof.Explainthedynamicstatewebpagedevelopmenttoolofthetype,suchasASP,PHP3etc.,becausespeedetc.reason,havealreadycantsatisfycurrentthelargeelectroniccommerceneedsappliedly,traditionaldevelopmenttechniquesareallattoeditandtranslatetheexecutivewaychange,suchastheASP→ASPPHP3→PHP4.IntheJSPnormbook,didnotrequesttheprocedureintheJSPcodepartbecalledtheScriptletandmustwritewiththeJavadefinitely.Actually,havesomeenginesofJSPareadoptiveotherscriptlanguagessuchastheEMACScript,etc.,butactuallythisafewscriptlanguagesalsoaretosetupontheJava,editandtranslatefortheServlettocarryoutof.WriteaccordingtothenormofJSP,havenoScriptletofrelationwithJavaalsoiscanof,however,mainlylieintheabilityandJavaBeans,theEnterpriseJavaBeansesbecauseoftheJSPstrongfunctiontoworktogether,soevenistheScriptletpartnottousetheJava,editandtranslateofperformancecodealsoshouldisrelatedwithJava.D.JSPmechanismTocomprehendtheJSPhowunitethetechnicaladvantagethatabovevariousspeakof,cometocarryoutvariousresulteasily,thecustomermustunderstandthedifferentiationofthemoduledevelopsforthewebpageofthecenterandthepagedevelopsforthewebpageofthecenterfirst.TheSSJSandASPareallinseveralyearagotorelease,thenetworkofthattimeisstillveryyoung,nooneknowstostillhaveinadditiontomakingallbusiness,datasandtheexpressionlogicentertheoriginalwebpageentirelyheapwhatbettersolvethemethod.Thiskindofmodelthattakepageasthecenterstudiesandgetstheveryfastdevelopmenteasily.However,alongwithchangeoftime,thepeopleknowthatthiskindofmethodisunwellinsetuplarge,theWebthatcanupgradeappliestheprocedure.Theexpressionlogicwriteinthescriptenvironmentwaslockinthepage,onlypassingtosheartosliceandgluetostickthencandriveheavyuse.Expressthelogictousuallymixtogetherwithbusinessandthedatalogics,whenthismakesbetheproceduremembertotrytochangeanexternalappearancethatappliestheprocedurebutdonotwanttobreakwithitslliedbusinesslogic,applytheprocedureofmaintenancebeliketowalkthesimilardifficultyontheeggshell.Infactinthebusinessenterprise,heavyusetheapplicationofthemodulealreadythroughverymature,noonewouldliketorewritethoselogicsfortheirappliedprocedure.HTMLandsketchthedesignerhandedovertotheimplementworkoftheirdesigntheWebplaittheonewhowrite,maketheyhavetodoubleworkUsuallyisthehandicraftplaittowrite,becausehavenofittoolandcancarrythescriptandtheHTMLcontentsknottotheservertoputtogether.Chienbutspeech,applythecomplexityoftheprocedurealongwiththeWebtopromotecontinuously,thedevelopmentmethodthattakepageasthecenterlimitssextobecometogetupobviously.Atthesametime,thepeoplealwaysatlookforthebettermethodofbuilduptheWebapplicationprocedure,themodulespreadsincustomersmachine/servertherealm.JavaBeansandActiveXwerepublishedthecompanytoexpandtoapplytheproceduredeveloperforJavaandWindowstousetocometodevelopthecomplicatedprocedurequicklybythefastapplicationproceduredevelopmentRADtool.Thesetechniquesmaketheexpertinthesomerealmbeabletowritethemodulefortheperpendicularapplicationplaitintheskillarea,butthedevelopercangofetchtheusagedirectlybutneednotcontroltheexpertiseofthisrealm.Beakindoftakemoduleasthecentraldevelopmentterrace,theJSPappeared.ItwiththeJavaBeansandEnterpriseJavaBeansEJBmoduleincludesthemodelofthebusinessandthedatalogicforfoundation,provideagreatdealoflabelandascriptterracestousetocometoshowintheHTMLpagefromthecontentsofJavaBeanscreationorsendapresentinreturn.BecauseofthepropertythatregardsthemoduleasthecenteroftheJSP,itcandriveJavaandnotthedeveloperofJavausesequally.NotthedeveloperofJavacanpasstheJSPlabelTagstousetheJavaBeansthatthedeluxedeveloperofJavaestablish.ThedeveloperofJavanotonlycanestablishandusetheJavaBeans,butalsocanusethelanguageofJavatocometocontrolmoreaccuratelyintheJSPpageaccordingtotheexpressionlogicofthefirstfloorJavaBeans.SeenowhowJSPishandleclaimofHTTP.Inbasicclaimmodel,aclaimdirectlywassendtoJSPpagein.ThecodeofJSPcontrolstocarryonhourofthelogicprocessingandmoduleofJavaBeanseshandoverwitheachother,andthemanifestationresultindynamicstatebornly,mixingwiththeHTMLpageofthestaticstateHTMLcode.TheBeanscanbeJavaBeansormoduleofEJBs.Moreover,themorecomplicatedclaimmodelcanseemakefromisrequestotherJSPpagesofthepagecallsignorJavaServlets.TheengineofJSPwantstochasethecodeofJavathatthelabelofJSP,codeofJavaintheJSPpageevenallconvertsintothebigpiecetogetherwiththestaticstateHTMLcontentsactually.ThesecodespiecewasorganizedtheJavaServletthatcustomercannotseetogotobytheengineofJSP,thentheServleteditsandtranslatethemautomaticallybytecodeofJava.Thus,thevisitantthatisthewebsiterequestsaJSPpage,undertheconditionofitisnotknowing,analreadyborn,theServletactualfullgeneralthatpreparedtoeditandtranslatecompletesallworks,veryconcealmentbutagainandefficiently.TheServletistoeditandtranslateof,sothecodeofJSPinthewebpagedoesnotneedwhentheeverytimerequeststhatpageisexplain.TheengineofJSPneedtobeeditandtranslateafterServletthecodeendismodifyonlyonce,thenthisServletthatedittedandtranslatecanbecarryout.TheinviewofthefactJSPengineautoisborntoeditandtranslatetheServletalso,neednotprocedurememberbeginstoeditandtranslatethecode,sotheJSPcanbringvividsexthatfunctionandfastdevelopmentsneedthatyouareefficiently.ComparedwiththetraditionalCGI,theJSPhastheequaladvantage.First,onthespeed,thetraditionalprocedureofCGIneedstousethestandardimportationofthesystemtooutputtheequipmentstocarryoutthedynamicstatewebpageborn,buttheJSPisdirectismutuallytheconnectionwithserver.AndsayfortheCGI,eachinterviewneedstoaddtoaddaprogresstohandle,theprogressbuildupanddestroybyburningconstantlyandwillbeanotsmallburdenforcalculatorofbetheserverofWeb.Thenextinorder,theJSPisspecializedtodevelopbutdesignfortheWebof,itspurposeisforbuildingupaccordingtotheWebappliedprocedure,includedthenormandthetoolofathewholeset.UsethetechniqueofJSPcancombinealotofJSPpagestobecomeaWebapplicationprocedureveryexpediently.