外文翻译-J2ME和Java领域

外文原文Java2MicroEditionandtheWorldofJava1IntroductionThecomputerrevolutionofthe1970sincreasedthedemandforsophisticatedcomputersoftwaretotakeadvantageoftheever-increasingcapacityofcomputerstoprocessdata.TheCprogramminglanguagebecamethelinchpinthatenabledprogrammerstobuildsoftwarethatwasjustasrobustasthecomputeritranon.Asthe1980sapproached,programmerswerewitnessinganotherspurtintheevolutionofprogramminglanguage.ComputertechnologyadvancedbeyondthecapabilitiesoftheCprogramminglanguage.Theproblemwasntnew.Itoccurredpreviouslyandcausedthedemiseofgenerationsofprogramminglanguages.Theproblemwasthatprogramswerebecomingtoocomplicatedtodesign,write,andmanagetokeepupwiththecapabilitiesofcomputers.ItwasaroundthistimethatadesignconceptbasedonSimula67andSmalltalk(fromthelate1960s)movedprogrammingtothenextevolutionarystep.Thiswastheperiodwhenobject-orientedprogramming(OOP),andwithitanewprogramminglanguagecalledC+,tookprogrammersbystorm.In1979,BjarneStroustrupofBellLaboratoriesinNewJerseyenhancedtheCprogramminglanguagetoincludeobject-orientedfeatures.HecalledthelanguageC+.(The+istheincrementaloperatorintheCprogramminglanguage.)C+istrulyanenhancementoftheCprogramminglanguage,anditbeganasapreprocessorlanguagethatwastranslatedintoCsyntaxbeforetheprogramwasprocessedbythecompiler.Stroustrupbuiltontheconceptofaclass(takenfromSimula67andSmalltalk),fromwhichinstancesofobjectsarecreated.Aclasscontainsdatamembersandmemberfunctionsthatdefineanobjectsdataandfunctionality.Healsointroducedtheconceptofinheritance,whichenabledaclasstoinheritsomeoralldatamembersandmemberfunctionsfromoneormoreotherclassesallofwhichcomplementstheconceptsofobject-orientedprogramming.By1988,ANSIofficialsstandardizedStroustrupsC+specification.2EnterJavaJustasC+wasbecomingthelanguageofchoiceforbuildingindustrial-strengthapplications,anothergrowthspurtintheevolutionofprogramminglanguagewasbudding,fertilizedbythelatestdisruptivetechnologytheWorldWideWeb.TheInternethadbeenawell-keptsecretfordecadesbeforetheNationalScienceFoundation(whooversawtheInternet)removedbarriersthatpreventedcommercialization.Until1991whenitwasopenedtocommerce,theInternetwasthealmostexclusivedomainofgovernmentagenciesandtheacademiccommunity.Oncethebarriertocommercializationwaslifted,theWorldWideWeboneofseveralservicesofferedontheInternetbecameavirtualcommunitycenterwherevisitorscouldgetfreeinformationaboutpracticallyanythingandbrowsethroughthousandsofvirtualstores.BrowserspowertheWorldWideWeb.AbrowsertranslatesASCIItextfileswritteninHTMLintoaninteractivedisplaythatcanbeinterpretedonanymachine.AslongasthebrowseriscompatiblewiththecorrectversionofHTMLandHTTPimplementation,anycomputerrunningthebrowsercanusethesameHTMLdocumentwithouthavingtomodifyitforaparticulartypeofcomputer,whichwassomethingunheardofatthetime.ProgramswritteninCorC+aremachinedependentandcannotrunonadifferentmachineunlesstheprogramisrecompiled.ThesuccessoftheInternetgaverenewedfocustodevelopingamachine-independentprogramminglanguage.AndthesameyeartheInternetwascommercialized,fivetechnologistsatSunMicrosystemssetouttodojustthat.JamesGosling,PatrickNaughton,ChrisWarth,EdFrank,andMikeSheridanspent18monthsdevelopingtheprogramminglanguagetheycalledOak,whichwasrenamedJavawhenthisnewlanguagemadeitsdebutin1995.Javawentthroughnumerousiterationsbetween1991and1995,duringwhichtimemanyothertechnologistsatSunmadesubstantialcontributionstothelanguage.TheseincludedBillJoy,ArthurvanHoff,JonathanPayne,FrankYelin,andTimLindholm.AlthoughJavaiscloselyassociatedwiththeInternet,itwasdevelopedasalanguageforprogrammingsoftwarethatcouldbeembeddedintoelectronicdevicesregardlessofthetypeofCPUusedbythedevice.ThisisknownastheEmbeddedJavaplatformandisincontinuoususetodayforclosedsystems.TheJavateamfromSunsucceededincreatingaportableprogramminglanguage,somethingthathadeludedprogrammerssincecomputerswerefirstprogrammed.Theirsuccess,however,wasfarbeyondtheirwildestdreams.ThesameconceptusedtomakeJavaprogramsportabletoelectronicdevicesalsocouldbeusedtomakeJavaprogramsrunoncomputersrunningMicrosoftWindows,UNIX,andMacintosh.Timingwasperfect.TheInternet/intranethadwhettedcorporateAmericasappetiteforcost-effective,portableprogramsthatcouldreplacemission-criticalapplicationswithinthecorporation.AndJavahadprovenitselfasaprogramminglanguageusedtosuccessfullydevelopmachine-independentapplications.3JavaVirtualMachineWritingJavaprogramsissimilartowritingC+programsinthattheprogrammerwritessourcecodethatcontainsinstructionsintoaneditor,orinanintegrateddevelopmentenvironment,andthenthesourcecodeiscompiled.However,thatswhereJavaandC+partways.ThecompilingandlinkingprocessofaC+programresultsinanexecutablethatcanberunonanappropriatemachine.Incontrast,theJavacompilerconvertsJavasourcecodeintobytecodethatisexecutedbytheJavaVirtualMachine(JVM).Machine-specificinstructionsarenotincludedinbytecode.Instead,theyalreadyresideintheJVM,whichismachinespecific.ThismeansthatthebytecodemightcontainfewerinstructionsthatneedtobetranslatedthanacomparableC+program.AlthoughtheJavacompilergeneratesbytecodethatmustbeinterpretedbytheJVMatruntime,thenumberofinstructionsthatneedtranslationareusuallyminimalandhavealreadybeenoptimizedbytheJavacompiler.Inmanyorganizations,databasedevelopmentfromthebeginningofenterprisedatamodeling,datamodelingenterprisesdeterminethescopeofthedatabaseandthegeneralcontent.Thisstepusuallyoccursinanorganizationsinformationsystemplanningprocess,itaimstohelporganizationscreateanoveralldatadescriptionorexplanation,andnotthedesignofaspecificdatabase.Aspecificdatabaseforoneormoreinformationsystemsprovidedataandthecorporatedatamodel(whichmayinvolveanumberofdatabases)describedbytheorganizationmaintainingthescopeofthedata.Datamodelingintheenterprise,youreviewofthecurrentsystem,theneedtosupportanalysisofthenatureofthebusinessareas,theneedforfurtherdescriptionoftheabstractdata,andplanningoneormoredatabasedevelopmentproject.Figure1showsPineValleyfurniturecompanysenterprisedatamodelofapart.1.1InformationSystemArchitectureAsshowninfigure1,seniordatamodelisonlygeneralinformationsystemarchitecture(ISA)orapartofanorganizationsinformationsystemblueprint.Intheinformationsystemplanning,youcanbuildanenterprisedatamodelasawholeinformationsystemarchitecturepart.AccordingtoZachman(1987),SowaandZachman(1992)viewsofaninformationsystemarchitectureconsistsofthefollowingsixkeycomponents:Data(Figure1shows,butthereareothermethodsthat).Manipulationofdataprocessing(ofadataflowdiagramcanbeused,withtheobjectmodelmethods,orothersymbolsthat).Networks,whichorganizationsandinorganizationswithitsmaintransmissionofdatabetweenbusinesspartners(itcanconnectthroughthenetworktopologymapandtodemonstrate).Peoplewhodealwiththeimplementationofdataandinformationandisthesourceandreceiver(intheprocessmodelforthedatashowsthatthesenderandthereceiver).Implementationoftheeventsandtimepoints(theycanusestatetransitiondiagramandothermeans.)Thereasonsfortheincidentanddataprocessingrules(oftenintheformoftextdisplay,buttherearealsoanumberofchartsfortheplanningtoolssuchasdecisiontables).1.2InformationEngineeringInformationsystemsplannersinaccordancewiththespecificinformationsystemplanningmethodsdevelopedinformationsystemarchitecture.Informationengineeringisapopularandformalmethods.Informationengineeringisadata-orientedcreationandmaintenanceoftheinformationsystem.Informationengineeringisbecausethedata-oriented,sowhenyoubegintounderstandhowthedatabaseisdefinedbythelogoandwheninformationengineeringaconciseexplanationisveryhelpful.InformationEngineeringfollowtop-downplanningapproach,inwhichspecificinformationsystemsfromawiderangeofinformationneedsintheunderstandingderivedfrom(forexample,weneedaboutcustomers,products,suppliers,salesandprocessingofthedatacenter),ratherthanmergingmanydetailedinformationrequested(orderssuchasascreenorinaccordancewiththeimportationofgeographicalsalessummaryreport).Top-downplanningwillenabledeveloperstoplanmorecomprehensiveinformationsystem,considersystemcomponentsprovideanintegratedapproachtoenhancetheinformationsystemandtherelationshipbetweenthebusinessobjectivesoftheunderstanding,deepentheirunderstandingofinformationsystemsthroughouttheorganizationinunderstandingtheimpact.InformationEngineeringincludesfoursteps:planning,analysis,designandimplementation.Theplanningstageofprojectinformationgeneratedinformationsystemarchitecture,includingenterprisedatamodel.1.3InformationSystemPlanningInformationsystemsplanningobjectiveistoenableITorganizationsandthebusinessstrategycloselyintegrated,suchintegrationfortheinformationsystemsandtechnologytomakethemostoftheinvestmentinterestisveryimportant.Asthetableasadescription,informationengineeringapproachtheplanningstageincludethreesteps,weinthefollow-upofthreesectionstheydiscussed.1.CriticalfactorsdeterminingtheplanningPlanningisthekeyfactorthatorganizationalobjectives,criticalsuccessfactorsandproblemareas.Thesefactorsdeterminethepurposeoftheestablishmentofplanningandenvironmentplanningandinformationsystemslinkedtostrategicbusinessplanning.Table2showsthePineValleyfurniturecompanyskeyplanninganumberofpossiblefactors,thesefactorscontributetotheinformationsystemsmanagerforthenewinformationsystemsanddatabasesclubstopprioritytodealwiththedemand.Forexample,giventheimprecisesalesforecaststhisproblemareas,informationsystemsmanagersintheorganizationmaybestoredinthedatabaseadditionalhistoricalsalesdata,newmarketresearchdataandnewproducttestdata.2.TheplanningorganizationssettargetsOrganizationsplanningtargetsdefinedscopeofbusiness,andbusinessscopewilllimitthesubsequentanalysisandinformationsystemsmaychangeplaces.Fivekeyplanningtargetsasfollows:anizationslocationoftheplaceofbusinessoperations.functionsofthebusinesssupportorganizationshandlingmissionoftherelevantgroup.Unlikebusinessorganizationsfunctionmodules,infactafunctioncanbeassignedtovariousorganizationsmodules(forexample,productdevelopmentfunctionistheproductionandsaleofthecommonresponsibilityoftheMinistry).typesofentitiesmanagedbytheorganizationonthepeople,placesandthingsofthemajortypesofdata.InformationSystemdatasetprocessingsoftwareapplicationsandsupportprocedures.3.TosetupabusinessmodelAcomprehensivebusinessmodelincludingthefunctionsofeachenterprisefunctionaldecompositionmodel,theenterprisedatamodelandthevariousplanningmatrix.Functionaldecompositionisthefunctionoftheorganizationforamoredetaileddecompositionprocess,thefunctionaldecompositionistosimplifytheanalysisoftheissue,distractedandidentifycomponentsandtheuseoftheclassicalapproach.PineValleyfurniturecompanyinordertofunctioninthefunctionaldecompositionexampleinfigure2below.Indealingwithbusinessfunctionsandsupportfunctionsofthefullset,multipledatabases,isessentialtoaspecificdatabasethereforelikelyonlytosupportfunctions(asshowninFigure2)provideasubsetofsupport.Inordertoreducedataredundancyandtomakedatamoremeaningful,hasacomplete,high-levelbusinessviewisveryhelpful.Theuseofspecificenterprisedatamodeltodescribethesymbol.Apartfromthegraphicaldescriptionofthistypeofentity,acompleteenterprisedatamodelshouldalsoincludeadescriptionofeachentitytypedescriptionofbusinessoperationsandasummaryofthatbusinessrules.Businessrulesdeterminethevalidityofthedata.Anenterprisedatamodelincludesnotonlythetypesofentities,includingthelinkbetweenthedataentities,aswellasvariousotherobjectsplanninglinks.Showedthatthelinkagebetweenplanningtargetsacommonformofmatrix.Becauseofplanningmatrixneednotbeexplicitmodelingdatabasecanbeclearlydescribedbusinessneeds,planningmatrixisanimportantfunction.Regularplanningmatrixderivedfromtheoperationalrules,itwillhelpsocialdevelopmentactivitiesthattopprioritywillbesortinganddevelopmentactivitiesunderthetop-downviewthroughanenterprise-wideapproachforthedevelopmentoftheseactivities.Therearemanytypesofplanningmatrixisavailable,theircommonalitiesare:locations-featuresshowbusinessfunctioninwhichtheimplementationofoperationallocations.unit-functionswhichshowedthatbusinessfunctionorbusinessunitresponsibleforimplementation.InformationSystem-dataentitiestoexplainhoweachinformationsysteminteractwitheachdataentity(forexample,whetherornoteachsystemineachentityhavethedatatocreate,retrieve,updateanddelete).supportfunctions-dataineachfunctionalentitiesinthedatasetfortheacquisition,use,updateanddelete.InformationSystem-targetindicationforeachinformationsystemtosupportbusinessobjectives.Figure3illustrateapossiblefunctions-dataentitiesmatrix.Suchamatrixcanbeusedforavarietyofpurposes,includingthefollowingthreeobjectives:1)identifygapsinthedataentitiestoindicatethetypesofentitiesnotuseanyfunctionorfunctionswhichdonotuseanyentity.2)foundthatthelossofeachfunctionalentitiesinvolvedintheinspectionstaffthroughthematrixtoidentifyanypossiblelossoftheentity.3)Thedistinctionbetweendevelopmentactivitiesiftheprioritytothetopofasystemdevelopmentfunctionforahigh-priority(probablybecauseitimportantorganizationalobjectivesrelated),thenthisareausedbyentitiesinthedevelopmentofthedatabasehasahighpriority.Hoffer,GeorgeandValacich(2002)aretheworksofthematrixonhowtousetheplanningandcompletionoftheInformationEngineeringTheplanningsystemmorecompletedescription.2databasedevelopmentprocessBasedoninformationengineeringinformationsystemsplanningdatabaseisasourceofdevelopmentprojects.Thesenewdatabasedevelopmentprojectsisusuallyinordertomeetthestrategicneedsoforganizations,suchasimprovingcustomersupport,improveproductandinventorymanagement,oramoreaccuratesalesforecast.However,manymoredatabasedevelopmentprojectisthebottom-upapproachemerging,suchasinformationsystemuserneedsspecificinformationtocompletetheirwork,thusbeginningaprojectrequest,andasotherinformationsystemsexpertsfoundthatorganizationsneedtoimprovedatamanagementandbeginnewprojects.Bottom-upeveninthecircumstances,tosetupanenterprisedatamodelisalsonecessarytounderstandtheexistingdatabasecanprovidethenecessarydata,otherwise,thenewdatabase,dataentitiesandattributescanbeaddedtothecurrentdataresourcestotheorganization.Boththestrategicneedsoroperationalinformationneedsofeachdatabasedevelopmentprojectsnormallyconcentratedinadatabase.Someprojectsonlyconcentratedinthedatabasedefinition,designandimplementationofadatabase,asafollow-uptothebasisofthedevelopmentofinformationsystems.However,inmostcases,thedatabaseandassociatedinformationprocessingfunctionasacompleteinformationsystemsdevelopmentprojectwaspartofthedevelopment.中文翻译J2ME和Java领域1介绍20世纪70年代以来随着计算机革命的开始，对计算机先进软件的需求大大增加，从而可以充分利用功能日益增强的精密的计算机的处理数据的能力。C编程语言逐渐成为支柱，使程序员开发软件像计算机运行一样流畅。80年代以来，程序员又目睹了编程语言领域的又一次变革的高潮。C语言的编程能力已经不能满足计算机的技术发展的需要。这问题并不是新问题。它造成了一代又一代的编程语言的新老更替。问题是，它使得程序设计过于复杂，从而使计算机软件的设计，编写和开发落后于硬件的发展。就是这个时候，两种基于设计概念的编程语言Simula67和Smalltalk（从上世纪60年代末）带来了接近编程语言未来前景的循序渐进的步骤。这期间，当面向对象编程（OOP），与它一种新的编程语言，所谓的C+在程序员中掀起了一场风暴。1979年，BjarneStroustrup的在新泽西州的贝尔实验室增强了C语言，使其具有面向对象的特点即所谓的C+语言（+是C编程语言增强的承载符号）。C+是一个真正的提高的C编程语言，它开始是一种前置语言，该计划最初是一种编译工具。Stroustrup建立类的概念（借用了Simula67和Smalltalk中的概念），由类则可以创建实例对象。一个类包含数据成员和定义对象数据和功能的成员函数。他还介绍了继承的概念，使一类继承其他一个或多个类的部分或全部数据成员或成员函数，职能由一个或多个其他类别-所有这些概念就是面向对象的编程。1988年由ANSI官员将C+标准化。走进JAVA正当C+作为企业开发所选择的语言时，由于最新的突破性技术-万维网的出现，别一种编程语言正在萌芽，并逐渐成熟。几十年来互联网对普通人来说还是个秘密，直到前美国国家科学基金会（监督互联网的机构）拆除了防止互联网商业化的壁垒。1991年当它向商贸开放时，互联网几乎是政府机构和学术团体的专利。一旦商业化的障碍被取消，万维网提供的几个服务，在互联网上成为虚拟社区中心，游客可以得到几乎任何的免费的资讯并浏览数以千计的虚拟商店。浏览器加强了万维网。浏览器转换将用HTML编写的ASCII文本文件转化成为一个互动的显示功能，并可以任何计算机上编译运行。只要浏览器是和HTML和HTTP兼容的正确版本，在任何电脑上运行的浏览器可以使用相同的HTML文件，而不是指定为某一特定类型的计算机，而在以前是闻所未闻的。而C或C+是依赖于机器的，并且不能运行于不同机器上，除非是重新编译。互联网的成功使人们将重点放在发展独立于机器的编程语言上。和同年在互联网上被商品化，科技工作者SunMicrosystems詹姆斯戈斯林，帕特里克诺顿，chriswarth，和麦克谢里登花了18个月发展规划，并在1995年向公众发布，他们所谓的Oak，后来改名为Java。Java在1991年和1995年期间经历了无数次的变革。那个时候，在Sun公司的许多其他科技人员对该语言的发展做出了重大贡献。Joy，阿瑟范霍夫，乔纳森佩恩，Yelin，添佩尔都分享了成功的喜悦。虽然Java是和互联网密切相关，但开始是为了开发一种可以嵌入到电子器件中去的软件的编程语言，而无论所用装置的CPU类型。这也是众所周知的所谓embeddedjava平台。Java团队从Sun成功地建立了一种可移植性的编程语言，电脑程序员进行了首次编程，一些已经实现。他们的成功远远超出了他们的梦想。同样可以使Java程序进行在各种可移植的电子装置上，也可以使Java程序在安装了MicrosoftWindows，UNIX和Macintosh的计算机上运行。这个时机很完美。因特网/内部网已使美国企业为符合公司成本效益，而开发应用于公司的可移植程序的兴趣。Java已被证明可以作为一种成功开发与机器无关的应用程序的编程语言。Java虚拟机写Java程序和写C+程序是相似的，这程序员可以编写：包含指示的源代码，成为一个编辑器，或在一个综合发展环境中对源代码进行编译。不过，这也就是Java和C+一部分的方式。该编译和链接的过程中一个C+程序的结果可以运行在一个适当的可执行的机器上。与此相反，Java编译器则将Java源代码转换成字节，即由Java虚拟机（JVM）执行。机器的具体指示，则不会包括在字节中。相反，他们已经包括在JVM的，这是属于具体机器的。这意味着该字节可能包含的C+程序要翻译的指令要少。在许多组织中，数据库开发是从企业数据建模开始的，企业数据建模确定了组织数据库的范围和一般内容。这一步骤通常发生在一个组织进行信息系统规划的过程中，它的目的是为组织数据创建一个整体的描述或解释，而不是设计一个特定的数据库。一个特定的数据库为一个或多个信息系统提供数据，而企业数据模型（可能包含许多数据库）描述了由组织维护的数据的范围。在企业数据建模时，你审查当前的系统，分析需要支持的业务领域的本质，描述需要进一步抽象的数据，并且规划一个或多个数据库开发项目。图1显示松谷家具公司的企业数据模型的一个部分。1.1信息系统体系结构如图1所示，高级的数据模型仅仅是总体信息系统体系结构(ISA)一个部分或一个组织信息系统的蓝图。在信息系统规划期间，你可以建立一个企业数据模型作为整个信息系统体系结构的一部分。根据Zachman(1987)、Sowa和Zachman（1992）的观点，一个信息系统体系结构由以下6个关键部分组成:数据（如图1所示，但是也有其他的表示方法）。操纵数据的处理（着系可以用数据流图、带方法的对象模型或者其他符号表示）。网络，它在组织内并在组织与它的主要业务伙伴之间传输数据（它可以通过网络连接和拓扑图来显示）。人，人执行处理并且是数据和信息的来源和接收者（人在过程模型中显示为数据的发送者和接收者）。执行过程的事件和时间点（它们可以用状态转换图和其他的方式来显示）。事件的原因和数据处理的规则（经常以文本形式显示，但是也存在一些用于规划的图表工具，如决策表）。1.2信息工程信息系统的规划者按照信息系统规划的特定方法开发出信息系统的体系结构。信息工程是一种正式的和流行的方法。信息工程是一种面向数据的创建和维护信息系统的方法。因为信息工程是面向数据的，所以当你开始理解数据库是怎样被标识和定义时，信息工程的一种简洁的解释是非常有帮助的。信息工程遵循自顶向下规划的方法，其中，特定的信息系统从对信息需求的广泛理解中推导出来（例如，我们需要关于顾客、产品、供应商、销售员和加工中心的数据），而不是合并许多详尽的信息请求（如一个订单输入屏幕或按照地域报告的销售汇总）。自顶向下规划可使开发人员更全面地规划信息系统，提供一种考虑系统组件集成的方法，增进对信息系统与业务目标的关系的理解，加深对信息系统在整个组织中的影响的理解。信息工程包括四个步骤:规划、分析、设计和实现。信息工程的规划阶段产