中英文翻译--Spring的web MVC 构架模式（精品doc）Word格式文档下载.docx

中英文翻译--Spring的web MVC 构架模式（精品doc）Word格式文档下载.docx

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JuergenHoeller

1. Introduction:

SpringtheApplicationFramework

WhenfirstconfrontedwiththeSpringFramework,onemightbetemptedtothink:

〃0hno,notyetanotherwebframework^.ThisarticlewilloutlinewhySpringisn，tparticularlyawebframeworkbutagenericlightweightapplicationframeworkwithdedicatedwebsupport,andshowthearchitecturaldifferencestoStrutsandWebWorkIncontrasttoStrutsorWebWork,Springisanapplicationframeworkforalllayers:

Itoffersabeanconfigurationfoundation,AOPsupport,aJDBCabstractionframework,abstracttransactionsupport,etc.Itisaverynon-intrusiveeffort:

YourapplicationclassesdonotneedtodependonanySpringclassesifnotnecessary,andyoucanreuseeverypartonitsownifyouliketo.Fromitsverydesign,theframeworkencouragescleanseparationoftiers,mostimportantlywebtierandbusinesslogic:

e.g.thevalidationframeworkdoesnotdependonwebcontrollers.Majorgoalsarereusabilityandtestability:

Unnecessarycontainerorframeworkdependenciescanbeconsideredavoidableevils.

Ofcourse,Spring，sownwebsupportisnicelyintegratedwiththeframework，sgeneralpatterns.Nevertheless,replacingthewebsolutionwithStruts,WebWork,orthelikeiseasy.BothwithSpring'

swebsupportoradifferentone,Springallowsforbuildingatruededicatedmiddletierinthewebcontainer,withtheoptiontoreuseexactlythesamebusinesslogicintestenvironmentsorstandaloneapplications.AndwithinJ2EE,yourbusinesslogicwillnotunnecessarilydependoncontainerserviceslikeJTAorEJB-allowingcomplex,we11-architectedwebapplicationstorunina"

simple"

containerlikeTomcatorResin.

NotethatSpringdoesn，tgenerallyaimtocompetewithexistingsolutions.ItratherfostersseamlessintegrationwithstandardslikeServlet,JSP,JTA,JNDI,JDBC,andJDO,andwell-suitedtoolslikeHibernate,Velocity,Log4J,andCaucho,sHessian/Burlap.Theframeworkisdesignedtogrowwiththeneedsofyourapplications,intermsoftechnologychoice:

Forexample,youwillprobablyuseJTAviaSpring，sJtaTransactionManagerifyouneeddistributedtransactions-butonlythen,asthereareperfectreplacementsforsingledatabases,likeDataSourceTransactionManagerorHibernateTransactionManager.

2. WebMVC:

TheDesignofSpring'

sWebFramework

Spring，swebframeworkisdesignedaroundaDispatcherServletthatdispatchesrequeststohandlers,withconfigurablehandlermappings,viewresolution,andlocaleandthemeresolution.ThedefaulthandlerisaverysimpleControllerinterface,justofferinga/zModelAndViewhandleRequest（request,response）〃method.Thiscanalreadybeusedforapplicationcontrollers,butyouwillprefertheincludedimplementationhierarchy,consistingofAbstractcontroller,AbstractCommandControIler,MultiActionController,SimpleFormController,AbstractWizardFormControIler.Applicationcontrollerswilltypicallybesubclassesofthose.Notethatyoucanchooseanappropriatebaseclass:

Ifyoudon，thaveaform,youdon，tneedaFormController.ThisisamajordifferencetoStruts.

Youcantakeanyobjectascommandorformobject:

There，snoneedtoimplementaninterfaceorderivefromabaseclass.Spring，sdatabindingishighlyflexible,e.g.ittreatstypemismatchesasvalidationerrorsthatcanbeevaluatedbytheapplication,notassystemerrors.Soyoudon，tneedtoduplicateyourbusinessobjects'

propertiesasStringsinyourformobjects,justtobeabletohandleinvalidsubmissions,ortoconverttheStringsproperly.Instead,it'

softenpreferabletobinddirectlytoyourbusinessobjects.ThisisanothermajordifferencetoStrutswhichisbuiltaroundrequiredbaseclasseslikeActionandActionForm-foreverytypeofaction.ComparedtoWebWork,Springhasmoredifferentiatedobjectroles:

ItsupportsthenotionofaController,anoptionalcommandorformobject,andamodelthatgetspassedtotheview.Themodelwillnormallyincludethecommandorformobjectbutalsoarbitraryreferencedata.Instead,aWebWorkActioncombinesallthoserolesintoonesingleobject.WebWorkdoesallowyoutouseexistingbusinessobjectsaspartofyourform,butjustbymakingthembeanpropertiesoftherespectiveActionclass.Finally,thesameActioninstancethathandlestherequestgetsusedforevaluationandformpopulationintheview.Thus,referencedataneedstobemodelledasbeanpropertiesoftheActiontoo.Thesearearguablytoomanyrolesinoneobject.

Regardingviews:

Spring'

sviewresolutionisextremelyflexible.AControllerimplementationcanevenwriteaviewdirectlytotheresponse,returningnullasModelAndView.Inthenormalcase,aModelAndViewinstanceconsistsofaviewnameandamodelMap,containingbeannamesandcorrespondingobjects（likeacommandorform,referencedata,etc）.Viewnam