2021年JAVAWeb外文文献毕业设计方案

THETECHNIQUEDEVELOPMENTHISTORYOFJSPBy:KathySierraandBertBatesSource:Servlet&JSPTheJavaServerPages(JSP)isakindofaccordingtowebofthescriptplaitdistancetechnique,similarcarriesthescriptlanguageofJavaintheserveroftheNetscapecompanyofserver-sideJavaScript(SSJS)andtheActiveServerPages(ASP)oftheMicrosoft.JSPcomparestheSSJSandASPtohavebettercanexpandsex,anditisnomoreexclusivethananyfactoryorsomeoneparticularserverofWeb.ThoughthenormofJSPistobedrawupbytheSuncompanyof,anyfactorycancarryouttheJSPonownsystem.TheAfterSunreleasetheJSP(theJavaServerPages)formally,thethiskindofnewWebapplicationdevelopmenttechniqueveryquicklycausedthepeople'sconcern.JSPprovidedaspecialdevelopmentenvironmentfortheWebapplicationthatestablishesthehighdynamicstate.AccordingtotheSunparlance,theJSPcanadapttoincludetheApacheWebServer,IIS4.0onthemarketatinsideof85%serverproduct.ThischapterwillintroducetherelatedknowledgeofJSPandDatabases,andJavaBeanrelatedcontents,isallcertainlyrougherintroductionamongthembasiccontents,sayperhapstoisaGuideonly,ifthereaderneedsthemoredetailedinformation,pleasingthebookofconsultthehomologousJSP.1.1GENERALIZETheJSP(JavaServerPages)isfromthecompanyofSunMicrosystemsinitiate,themanycompaniestheparticipatetothebuildupthetogetheroftheakindtheofdynamicthestatewebthepagetechniquestandard,theithavetheitintheconstructiontheofthedynamicstatethewebpagethestrongbutthedonottheespeciallyofthefunction.JSPandthetechniqueofASPoftheMicrosoftisveryalike.BothallprovidetheabilitythatmixeswithacertainprocedurecodeandisexplainbythelanguageenginetocarryouttheprocedurecodeinthecodeofHTML.Underneathwearesimpleofcarryontheintroductiontoit.JSPpagesaretranslatedintoservlets.So,fundamentally,anytaskJSPpagescanperformcouldalsobeaccomplishedbyservlets.However,thisunderlyingequivalencedoesnotmeanthatservletsandJSPpagesareequallyappropriateinallscenarios.Theissueisnotthepowerofthetechnology,itistheconvenience,productivity,andmaintainabilityofoneortheother.Afterall,anythingyoucandoonaparticularcomputerplatformintheJavaprogramminglanguageyoucouldalsodoinassemblylanguage.Butitstillmatterswhichyouchoose.JSPprovidesthefollowingbenefitsoverservletsalone:•ItiseasiertowriteandmaintaintheHTML.YourstaticcodeisordinaryHTML:noextrabackslashes,nodoublequotes,andnolurkingJavasyntax.•YoucanusestandardWeb-sitedevelopmenttools.EvenHTMLtoolsthatknownothingaboutJSPcanbeusedbecausetheysimplyignoretheJSPtags.•Youcandivideupyourdevelopmentteam.TheJavaprogrammerscanworkonthedynamiccode.TheWebdeveloperscanconcentrateonthepresentationlayer.Onlargeprojects,thisdivisionisveryimportant.Dependingonthesizeofyourteamandthecomplexityofyourproject,youcanenforceaweakerorstrongerseparationbetweenthestaticHTMLandthedynamiccontent.Now,thisdiscussionisnottosaythatyoushouldstopusingservletsanduseonlyJSPinstead.Bynomeans.Almostallprojectswilluseboth.Forsomerequestsinyourproject,youwilluseservlets.Forothers,youwilluseJSP.Forstillothers,youwillcombinethemwiththeMVCarchitecture.YouwanttheapGFDGpropriatetoolforthejob,andservlets,bythemselves,donotcompleteyourtoolkit.1.2SOURCEOFJSPThetechniqueofJSPofthecompanyofSun,makingthepageofWebdevelopthepersonnelcanusetheHTMLperhapsmarkingofXMLtodesigntoturntheendpagewithformat.UsetheperhapssmallscriptfuturelifeofmarkingofJSPbecomesthedynamicstateonthepagecontents.(thecontentschangesaccordingtotheclaimof)TheJavaServletisatechnicalfoundationofJSP,andthelargeWebappliesthedevelopmentoftheproceduretoneedtheJavaServlettomatchwithwiththeJSPandthencancomplete,thisnameofServletcomesfromtheApplet,thelocaltranslationmethodofnowisalotof,thisbookinordernottomisconstruction,decidethedirectadoptionServletbutdon'tdoanytranslation,ifreaderwouldliketo,cancallitas"smallserviceprocedure".TheServletissimilartotraditionalCGI,ISAPI,NSAPIetc.Webproceduredevelopmentthefunctionofthetoolinfact,atusetheJavaServlethereafter,thecustomerneednotuseagainthelowlymethodofCGIofefficiency,alsoneednotuseonlytheabilitycometobornpageofWebofdynamicstateinthemethodofAPIthatacertainfixedWebserverterracecirculate.ManyserversofWeballsupporttheServlet,evennotsupporttheServletserverofWebdirectlyandcanalsopasstheadditionalappliedserverandthemoldpiecestosupporttheServlet.ReceivebenefitinthecharacteristicoftheJavacross-platform,theServletisalsoaterraceirrelevant,actually,aslongasmatchthenormofJavaServlet,theServletiscompletetohavenothingtodowithterraceandistohavenothingtodowithserverofWeb.BecausetheJavaServletisinternaltoprovidetheservicebythelinedistance,neednotstartaprogresstotheeachclaimses,andmakeuseofthemulti-threadingmechanismcanatthesametimeforseveralclaimservice,thereforetheefficiencyofJavaServletisveryhigh.ButtheJavaServletalsoisnottohasnoweakness,similartotraditionalCGI,ISAPI,theNSAPImethod,theJavaServletistomakeuseoftooutputtheHTMLlanguagesentencetocarryoutthedynamicstatewebpageof,ifdevelopthewholewebsitewiththeJavaServlet,theintegrationprocessofthedynamicstatepartandthestaticstatepageisanevil-forebodingdreamsimply.ForsolvingthiskindofweaknessoftheJavaServlet,theSUNreleasedtheJSP.Anumberofyearsago,Martywasinvitedtoattendasmall20-personindustryroundtablediscussiononsoftwaretechnology.SittingintheseatnexttoMartywasJamesGosling,inventoroftheJavaprogramminglanguage.Sittingseveralseatsawaywasahigh-levelmanagerfromaverylargesoftwarecompanyinRedmond,Washington.Duringthediscussion,themoderatorbroughtupthesubjectofJini,whichatthattimewasanewJavatechnology.Themoderatoraskedthemanagerwhathethoughtofit,andthemanagerrespondedthatitwastooearlytotell,butthatitseemedtobeanexcellentidea.Hewentontosaythattheywouldkeepaneyeonit,andifitseemedtobecatchingon,theywouldfollowhiscompany'susual"embraceandextend"strategy.Atthispoint,Goslinglightheartedlyinterjected"Youmeandisgraceanddistend."Now,thegrievancethatGoslingwasairingwasthathefeltthatthiscompanywouldtaketechnologyfromothercompaniesandsubornitfortheirownpurposes.Butguesswhat?Theshoeisontheotherfoothere.TheJavacommunitydidnotinventtheideaofdesigningpagesasamixtureofstaticHTMLanddynamiccodemarkedwithspecialtags.Forexample,ColdFusiondidityearsearlier.EvenASP(aproductfromtheverysoftwarecompanyoftheaforementionedmanager)popularizedthisapproachbeforeJSPcamealonganddecidedtojumponthebandwagon.Infact,JSPnotonlyadoptedthegeneralidea,itevenusedmanyofthesamespecialtagsasASPdid.TheJSPisanestablishmentatthemodelofJavaservletsonoftheexpressionlayertechnique,itmakestheplaitwritetheHTMLtobecomemoresimple.BeliketheSSJS,italsoallowsyoucarrythestaticstateHTMLcontentsandserversthescriptmixtoputtogethertheborndynamicstateexportation.JSPthescriptlanguagethattheJavaisthetacitapproval,however,beliketheASPandcanuseotherlanguages(suchasJavaScriptandVBScript),thenormofJSPalsoallowstouseotherlanguages.1.3JSPCHARACTERISTICSIsaserviceaccordingtothescriptlanguageinsomeonelanguageofthestaturessystemthiskindofdiscuss,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,havealreadycan'tsatisfycurrentthelargeelectroniccommerceneedsappliedly,traditionaldevelopmenttechniquesareallattoeditandtranslatetheexecutivewaychange,suchastheASP→ASP+;PHP3→PHP4.IntheJSPnormbook,didnotrequesttheprocedureintheJSPcodepart(becalledtheScriptlet)andmustwritewiththeJavadefinitely.Actually,havesomeenginesofJSPareadoptiveotherscriptlanguagessuchastheEMAC-Script,etc.,butactuallythisafewscriptlanguagesalsoaretosetupontheJava,editandtranslatefortheServlettocarryoutof.WriteaccordingtothenormofJSP,havenoScriptletofrelationwithJavaalsoiscanof,however,mainlylieintheabilityandJavaBeans,theEnterpriseJavaBeansesbecauseoftheJSPstrongfunctiontoworktogether,soevenistheScriptletpartnottousetheJava,editandtranslateofperformancecodealsoshouldisrelatedwithJava.1.4JSPMECHANISMTocomprehendtheJSPhowunitethetechnicaladvantagethatabovevariousspeakof,cometocarryoutvariousresulteasily,thecustomermustunderstandthedifferentiationof"themoduledevelopsforthewebpageofthecenter"and"thepagedevelopsforthewebpageofthecenter"first.TheSSJSandASPareallinseveralyearagotorelease,thenetworkofthattimeisstillveryyoung,nooneknowstostillhaveinadditiontomakingallbusiness,datasandtheexpressionlogicentertheoriginalwebpageentirelyheapwhatbettersolvethemethod.Thiskindofmodelthattakepageasthecenterstudiesandgetstheveryfastdevelopmenteasily.However,alongwithchangeoftime,thepeopleknowthatthiskindofmethodisunwellinsetuplarge,theWebthatcanupgradeappliestheprocedure.Theexpressionlogicwriteinthescriptenvironmentwaslockinthepage,onlypassingtosheartosliceandgluetostickthencandriveheavyuse.Expressthelogictousuallymixtogetherwithbusinessandthedatalogics,whenthismakesbetheproceduremembertotrytochangeanexternalappearancethatappliestheprocedurebutdonotwanttobreakwithitslliedbusinesslogic,applytheprocedureofmaintenancebeliketowalkthesimilardifficultyontheeggshell.Infactinthebusinessenterprise,heavyusetheapplicationofthemodulealreadythroughverymature,noonewouldliketorewritethoselogicsfortheirappliedprocedure.HTMLandsketchthedesignerhandedovertotheimplementworkoftheirdesigntheWebplaittheonewhowrite,maketheyhavetodoublework-Usuallyisthehandicraftplaittowrite,becausehavenofittoolandcancarrythescriptandtheHTMLcontentsknottotheservertoputtogether.Chienbutspeech,applythecomplexityoftheprocedurealongwiththeWebtopromotecontinuously,thedevelopmentmethodthattakepageasthecenterlimitssextobecometogetupobviously.Atthesametime,thepeoplealwaysatlookforthebettermethodofbuilduptheWebapplicationprocedure,themodulespreadsincustomer'smachine/servertherealm.JavaBeansandActiveXwerepublishedthecompanytoexpandtoapplytheproceduredeveloperforJavaandWindowstousetocometodevelopthecomplicatedprocedurequicklyby"thefastapplicationproceduredevelopment"(RAD)tool.Thesetechniquesmaketheexpertinthesomerealmbeabletowritethemodulefortheperpendicularapplicationplaitintheskillarea,butthedevelopercangofetchtheusagedirectlybutneednotcontroltheexpertiseofthisrealm.Beakindoftakemoduleasthecentraldevelopmentterrace,theJSPappeared.ItwiththeJavaBeansandEnterpriseJavaBeans(EJB)moduleincludesthemodelofthebusinessandthedatalogicforfoundation,provideagreatdealoflabelandascriptterracestousetocometoshowintheHTMLpagefromthecontentsofJavaBeanscreationorsendapresentinreturn.BecauseofthepropertythatregardsthemoduleasthecenteroftheJSP,itcandriveJavaandnotthedeveloperofJavausesequally.NotthedeveloperofJavacanpasstheJSPlabel(Tags)tousetheJavaBeansthatthedeluxedeveloperofJavaestablish.ThedeveloperofJavanotonlycanestablishandusetheJavaBeans,butalsocanusethelanguageofJavatocometocontrolmoreaccuratelyintheJSPpageaccordingtotheexpressionlogicofthefirstfloorJavaBeans.SeenowhowJSPishandleclaimofHTTP.Inbasicclaimmodel,aclaimdirectlywassendtoJSPpagein.ThecodeofJSPcontrolstocarryonhourofthelogicprocessingandmoduleofJavaBeanses'handoverwitheachother,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.JSP技术发展历史作者：KathySierraandBertBates起源：Servlet&JSPJavaServerPages(JSP)是一个基于web脚本编程技术，类似于网景企业服务器端Java脚本语言——server-sideJavaScript(SSJS)和微软ActiveServerPages(ASP)。和SSJS和ASP相比，JSP含有愈加好可扩展性，而且它不专属于任何一家厂商或某一特定Web服务器。尽管JSP 规范 编程规范下载gsp规范下载钢格栅规范下载警徽规范下载建设厅规范下载 是由Sun企业制订，但任何厂商全部能够在自己系统上实现JSP。在Sun正式公布JSP(JavaServerPages)以后，这种新Web应用开发技术很快引发了大家关注。JSP为创建高度动态Web应用提供了一个独特开发环境。根据Sun说法，JSP能够适应市场上包含ApacheWebServer、IIS4.0在内85%服务器产品。本文将介绍JSP相关知识，和JavaBean相关内容，当然全部是比较粗略介绍其中基础内容，仅仅起到抛砖引玉作用，假如读者需要更具体信息，请参考对应JSP 书 关于书的成语关于读书的排比句社区图书漂流公约怎么写关于读书的小报汉书pdf 籍。1.1概述JSP(JavaServerPages)是由SunMicrosystems企业提倡、很多企业参与一起建立一个动态网页技术 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 ，其在动态网页建设中有其强大而尤其功效。JSP和MicrosoftASP技术很相同。二者全部提供在HTML代码中混合某种程序代码、由语言引擎解释实施程序代码能力。下面我们简单对它进行介绍。JSP页面最终会转换成servlet。所以，从根本上，JSP页面能够实施任何任务全部能够用servlet来完成。然而，这种底层等同性并不意味着servlet和JSP页面对于全部情况全部等同适用。问题不在于技术能力，而是二者在便利性、生产率和可维护性上不一样。毕竟，在特定平台上能够用Java编程语言完成事情，一样能够用汇编语言来完成，不过选择哪种语言依旧十分关键。和单独使用servlet相比，JSP提供下述好处：JSP中HTML编写和维护更为简单。JSP中能够使用常规HTML：没有额外反斜杠，没有额外双引号，也没有暗含Java语法。能够使用标准网站开发工具。即使是那些对JSP一无所知HTML工具，我们也能够使用，因为它们会忽略JSP标签（JSPtags）。能够对开发团体进行划分。Java程序员能够致力于动态代码。Web开发人员能够将经理集中在表示层（presentationlayer）上。对于大型项目，这种划分极为关键。依据开发团体大小，及项目标复杂程度，能够对静态HTML和动态内容进行弱分离（weakerseparation）和强分离（strongerseparation）。此处讨论并不是说大家应该放弃使用servlet而仅仅使用JSP。实际上，几乎全部项目全部会同时用到这两种技术。在一些项目中，更适宜选择servlet，而针对项目中一些请求，我们可能会在MVC构架下组合使用这两项技术。我们总是期望用合适工具完成相对应工作，仅仅是servlet并不一定能够胜任全部工作。1.2JSP由来Sun企业JSP技术，使Web页面开发人员能够使用HTML或XML标识来 设计 领导形象设计圆作业设计ao工艺污水处理厂设计附属工程施工组织设计清扫机器人结构设计 和格式化最终页面。使用JSP标识或小脚原来生成页面上动态内容(内容是依据请求来改变)。JavaServlet是JSP技术基础，而且大型Web应用程序开发需要JavaServlet和JSP配合才能完成，Servlet这个名称源于Applet，现在中国翻译方法很多，本书为了避免误会，决定直接采取Servlet而不做任何翻译，读者假如愿意，能够称之为“小服务程序”。Servlet其实和传统CGI、ISAPI、NSAPI等Web程序开发工具作用是相同，在使用JavaServlet以后，用户无须再使用效率低下CGI方法，也无须使用只能在某个固定Web服务器平台运行API方法来动态生成Web页面。很多Web服务器全部支持Servlet，即使不直接支持ServletWeb服务器也能够经过附加应用服务器和模块来支持Servlet。得益于Java跨平台特征，Servlet也是平台无关，实际上，只要符合JavaServlet规范，Servlet是完全和平台无关且是和Web服务器无关。因为JavaServlet内部是以线程方法提供服务，无须对于每个请求全部开启一个进程，而且利用多线程机制能够同时为多个请求服务，所以JavaServlet效率很高。但JavaServlet也不是没有缺点，和传统CGI、ISAPI、NSAPI方法相同，JavaServlet是利用输出HTML语句来实现动态网页，假如用JavaServlet来开发整个网站，动态部分和静态页面整合过程会很难以实现。为了处理JavaServlet这种缺点，SUN推出了JSP。很多年前，Marty受到邀请,参与一个相关软件技术小型研讨会.坐在Marty旁边人是JamesGosling---Java编程语言发明者。隔多个位置,是来自华盛顿一家大型软件企业高级经理。在讨论过程中,研讨会主席提出了Jini议题,这在当初是一项新Java技术。主席向该经理问询她想法.她回复说,即使现在言之过早，但这看起来会是很有前途一项技术。她们会连续关注这项技术,假如这项技术变得流行起来,她们会遵照企业“接收并扩充(embraceandextend)”策略.此时,Gosling随意地插话说“你意思其实就是不接收且不扩充(disgraceanddistend)。”在此,Gosling埋怨显示出，她感到这个企业会从其它企业那里拿走技术,用于她们自己目标.出人意料是，形势已经完全不一样。Java团体并没有发明这一思想----将页面设计成由静态HTML和用特殊标签标识动态代码混合组成.。ColdFusion多年前就已经这么做了。甚至ASP(来自于前述经理所在企业一项产品)全部在JSP出现之前推广了这种方法。实际上,JSP不只采取了这种通用概念,它甚至使用很多和ASP相同特殊标签。JSP是建立在Javaservlets模型之上表示层技术，它使编写HTML变得更简单。像SSJS一样，它也许可你将静态HTML内容和服务器端脚本混合起来生成动态输出。JSP把Java作为默认脚本语言，然而，就像ASP能够使用其它语言(如JavaScript和VBScript)一样，JSP规范也许可使用其它语言。1.3JSP特点根据脚本语言是服务于某一个子系统语言这种叙述，JSP应该被看作是一个脚本语言。然而，作为一个脚本语言，JSP又显得过于强大了，在JSP中几乎能够使用全部Java类。作为一个基于文本、以显示为中心开发技术，JSP提供了JavaServlet全部好处，而且，当和一个JavaBeans类结合在一起时，JSP提供了一个使内容和显示逻辑分开简单方法。分开内容和显示逻辑好处是，更新页面外观人员无须知道Java代码，而更新JavaBeans类人员也无须是设计网页行家里手，就能够用带JavaBeans类JSP页面来定义Web模板，以建立一个由含有相同外观页面组成网站。JavaBeans类完成数据提供，这么在模板中就没有Java代码，这意味着这些模板能够由一个HTML编写人员来维护。当然，也能够利用JavaServlet来控制网站逻辑，经过JavaServlet调用JSP文件方法来将网站逻辑和内容分离。通常来说，在实际JSP引擎中，JSP页面在实施时是编译式，而不是解释式。解释式动态网页开发工具如ASP、PHP3等因为速度等原因已经满足不了目前大型电子商务应用需要了，传统开发技术全部在向编译实施方法改变，如ASP→ASP+；PHP3→PHP4。在JSP规范书中，并没有明确要求JSP中程序代码部分(称为Scriptlet)一定要用Java来写。实际上，有部分JSP引擎就是采取其它脚本语言，如EMAC-Script、WebL等，但实际上这多个脚本语言也是构建在Java上面，编译为Servlet来实现。根据JSP规范书写，和Java没有任何关系Scriptlet也是能够，不过，因为JSP强大功效关键在于能和JavaBeans、EnterpriseJavaBeans共同运转，所以即使是Scriptlet部分不使用Java，编译成实施代码也应该是和Java相关。1.4JSP机制要了解JSP怎样联合以上多种所提到技术优点，从而轻而易举地实现多种效果，用户必需首先了解“组件为中心网页开发”和“页面为中心网页开发”区分。SSJS和ASP全部是在几年前推出，那时网络还很年轻，没有些人知道除了把全部商务、数据和表示逻辑统统堆进原始网页中之外还有什么愈加好处理方法。这种以页面为中心模型轻易学习而且得到相当快速发展。然而，伴随时间推移，大家认识到这种方法不适于构建大型、可升级Web应用程序。在脚本环境中书写表示逻辑被锁在页面内，只有经过剪切和粘贴才能被重用。表示逻辑通常和商务及数据逻辑混在一起，这使适当程序员试图改变一个应用程序外观而不想破坏和之紧密结合商务逻辑时，应用程序维护就变得十分艰苦。其实际上，企业中可重用组件应用早已经很成熟，没有些人愿意为它们应用程序重写那些逻辑。HTML和图形设计师把它们设计实 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作交给了Web编写者，使她们不得不加倍工作——常常是手工编写，因为没有适宜工具能够把服务器端脚本和HTML内容结合起来。简而言之，伴随Web应用程序复杂性不停提升，以页面为中心开发方法不足变得显著起来。和此同时，大家一直在寻求建立Web应用程序愈加好方法，组件在用户机/服务器领域流行起来。JavaBeans和ActiveX被“快速应用程序开发”(RAD)工具发行商推广给Java和Windows应用程序开发者用来快速开发复杂程序。这些技术使某领域内教授能够为本事域内垂直应用编写组件，而开发者能够直接拿来使用而无须掌握这一领域专门技术。作为一个以组件为中心开发平台，JSP出现了。它以JavaBeans和EnterpriseJavaBeans(EJB)组件包含商务和数据逻辑模型为基础，提供大量标签和一个脚本平台用来在HTML页中显示由JavaBeans产生或回送内容。因为JSP以组件为中心性质，它能够被Java和非Java开发者一样使用。非Java开发者能够经过JSP标签(Tags)来使用高级Java开发者创建JavaBeans。Java开发者不仅能够创建和使用JavaBeans，还能在JSP页中使用Java语言来更精密地控制基于底层JavaBeans表示逻辑。现在来看看JSP是怎样处理HTTP请求。在基础请求模型中，一个请求直接被送到JSP页中。JSP代码控制着进行逻辑处理时和JavaBeans组件交互，并在动态生成、混合了静态HTML代码HTML页中显示结果。Beans能够是JavaBeans或EJB组件。另外，愈加复杂请求模型可看作从被请求页呼叫其它JSP页或JavaServlets。JSP引擎实际上要把JSP标签、JSP页中Java代码甚至连同静态HTML内容全部转换为大块Java代码。这些代码块被JSP引擎组织到用户看不到JavaServlet中去，然后Servlet自动把它们编译成Java字节码。这么，当网站访问者请求一个JSP页时，在它不知道情况下，一个已经生成、预编译过Servlet实际上将完成全部工作，很隐蔽而又高效。因为Servlet是编译过，所以网页中JSP代码不需要在每次请求该页时被解释一遍。JSP引擎只需在Servlet代码最终被修改后编译一次，然后这个编译过Servlet就能够被实施了。因为是JSP引擎自动生成并编译Servlet，不用程序员动手编译代码，所以JSP能带给你高效性能和快速开发所需灵活性。和传统CGI相比较，JSP有相当优势。首先，在速度上，传统CGI程序需要使用系统标准输入输出设备来实现动态网页生成，而JSP是直接和服务器相关联。而且对于CGI来说，每一个访问就需要新增加一个进程来处理，进程不停地建立和销毁对于作为Web服务器计算机将是不小负担。其次，JSP是专门为Web开发而设计，其目标是为了建立基于Web应用程序，其中包含了一整套规范和工具。使用JSP技术能够很方便地将一大堆JSP页面组合成为一个Web应用程序。