毕业论文外文翻译-Spring 框架简介.docx

毕业论文外文翻译-Spring 框架简介.docx

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IntroducingtheSpringFramework

TheSpringFramework:

apopularopensourceapplicationframeworkthataddressesmanyoftheissuesoutlinedinthisbook.ThischapterwillintroducethebasicideasofSpringanddis-cussthecentral"beanfactory"lightweightInversion-of-Control（loC）containerindetail.

Springmakesitparticularlyeasytoimplementlightweight,yetextensible,J2EEarchi-tectures.Itprovidesanout—of—the—boximplementationofthefundamentalarchitecturalbuildingblockswerecommend.Springprovidesaconsistentwayofstructuringyourapplications,andprovidesnumerousmiddletierfeaturesthatcanmakeJ2EEdevelopmentsignificantlyeasierandmoreflexiblethanintraditionalapproaches.

ThebasicmotivationsforSpringare:

Toaddressareasnotwellservedbyotherframeworks.TherearenumerousgoodsolutionstospecificareasofJ2EEinfrastructure:

webframeworks,persistencesolutions,remotingtools,andsoon.However,integratingthesetoolsintoacomprehensivearchitecturecaninvolvesignificanteffort,andcanbecomeaburden.Springaimstoprovideanend-to-endsolution,integratingspe-cializedframeworksintoacoherentoverallinfrastructure.Springalsoaddressessomeareasthatotherframeworksdon't.Forexample,fewframeworksaddressgenerictransactionmanagement,dataaccessobjectimplementation,andgluingallthosethingstogetherintoanapplication,whilestillallowingforbest-of-breedchoiceineacharea.HencewetermSpringanapplicationframework,ratherthanawebframework,loCorAOPframework,orevenmiddletierframework.

Toallowforeasyadoption.Aframeworkshouldbecleanlylayered,allowingtheuseofindi-vidualfeatureswithoutimposingawholeworldviewontheapplication.ManySpringfeatures,suchastheJDBCabstractionlayerorHibernateintegration,canbeusedinalibrarystyleoraspartoftheSpringend-to-endsolution.

Todelivereaseofuse.Aswe'venoted,J2EEoutoftheboxisrelativelyhardtousetosolvemanycommonproblems.Agoodinfrastructureframeworkshouldmakesimpletaskssimpletoachieve,withoutforcingtradeoffsforfuturecomplexrequirements（likedistributedtransactions）ontheapplicationdeveloper.ItshouldallowdeveloperstoleverageJ2EEservicessuchasJTAwhereappropriate,buttoavoiddependenceonthemincaseswhentheyareunnecessarilycomplex.

Tomakeiteasiertoapplybestpractices.Springaimstoreducethecostofadheringtobestpracticessuchasprogrammingtointerfaces,ratherthanclasses,almosttozero.However,itleavesthechoiceofarchitecturalstyletothedeveloper.

Non-invasiveness.Applicationobjectsshouldhaveminimaldependenceontheframework.IfleveragingaspecificSpringfeature,anobjectshoulddependonlyonthatparticularfeature,whetherbyimplementingacallbackinterfaceorusingtheframeworkasaclasslibrary.loCandAOParethekeyenablingtechnologiesforavoidingframeworkdependence.

Consistentconfiguration.Agoodinfrastructureframeworkshouldkeepapplicationconfigurationflexibleandconsistent,avoidingtheneedforcustomsingletonsandfactories.Asinglestyleshouldbeapplicabletoallconfigurationneeds,fromthemiddletiertowebcontrollers.

Easeoftesting.Testingeitherwholeapplicationsorindividualapplicationclassesinunittestsshouldbeaseasyaspossible.Replacingresourcesorapplicationobjectswithmockobjectsshouldbestraightforward.

Toallowforextensibility.BecauseSpringisitselfbasedoninterfaces,ratherthanclasses,itiseasytoextendorcustomizeit.

ManySpringcomponentsusestrategyinterfaces,allowingeasycustomization.

ALayeredApplicationFramework

Chapter6introducedtheSpringFrameworkasalightweightcontainer,competingwithloCcontainerssuchasPicoContainer.WhiletheSpringlightweightcontainerforJavaBeansisacoreconcept,thisisjustthefoundationforasolutionforallmiddlewarelayers.

BasicBuildingBlocks

pringisafull-featuredapplicationframeworkthatcanbeleveragedatmanylevels.Itconsistsofmulti-plesub-frameworksthatarefairlyindependentbutstillintegratecloselyintoaone-stopshop,ifdesired.Thekeyareasare:

Beanfactory.TheSpringlightweightloCcontainer,capableofconfiguringandwiringupJava-BeansandmostplainJavaobjects,removingtheneedforcustomsingletonsandadhocconfigura-1ion.Variousout-of—the—boximplementationsincludeanXML-basedbeanfactory.ThelightweightloCcontaineranditsDependencyInjectioncapabilitieswillbethemainfocusofthischapter.

Applicationcontext.ASpringapplicationcontextextendsthebeanfactoryconceptbyaddingsupportformessagesourcesandresourceloading,andprovidinghooksintoexistingenviron-ments.Variousout-of-the~boximplementationsincludestandaloneapplicationcontextsandanXML-basedwebapplicationcontext.

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