外文翻译 外文文献 英文文献 将servlet和jsp组合使用

COMBININGJSPANDSERVLETSTHETECHNOLOGYOFJSPANDSERVLETISTHEMOSTIMPORTANTTECHNOLOGYWHICHUSEJAVATECHNOLOGYTOEXPLOITREQUESTOFSERVER,ANDITISALSOTHESTANDARDWHICHEXPLOITBUSINESSAPPLICATIONJAVADEVELOPERSPREFERTOUSEITFORAVARIETYOFREASONS,ONEOFWHICHISALREADYFAMILIARWITHTHEJAVALANGUAGEFORTHEDEVELOPMENTOFTHISTECHNOLOGYAREEASYTOLEARNJAVATOTHEOTHERIS“APREPARATION,RUNEVERYWHERE“TOBRINGTHECONCEPTOFWEBAPPLICATIONS,TOACHIEVEA“ONEPREPAREDEVERYWHEREREALIZED“ANDMOREIMPORTANTLY,IFFOLLOWEDSOMEOFTHEPRINCIPLESOFGOODDESIGN,ITCANBESAIDOFSEPARATINGANDCONTENTTOCREATEHIGHQUALITY,REUSABLE,EASYTOMAINTAINANDMODIFYTHEAPPLICATIONFOREXAMPLE,IFTHEDOCUMENTINHTMLEMBEDDEDJAVACODETOOMUCHSCRIPT,WILLLEADTHEDEVELOPEDAPPLICATIONISEXTREMELYCOMPLEX,DIFFICULTTOREAD,ITISNOTEASYREUSE,BUTALSOFORFUTUREMAINTENANCEANDMODIFICATIONWILLALSOCAUSEDIFFICULTIESINFACT,CSDNTHEJSP/SERVLETFORUM,CANOFTENSEESOMEQUESTIONS,THECODEISVERYLONG,CANLOGICISNOTVERYCLEAR,ALARGENUMBEROFHTMLANDJAVACODEMIXEDTOGETHERTHISISTHERANDOMDEVELOPMENTOFTHEDEFECTSEARLYDYNAMICPAGESMAINLYCGICOMMONGATEWAYINTERFACE,PUBLICGATEWAYINTERFACETECHNOLOGY,YOUCANUSEDIFFERENTLANGUAGESOFTHECGIPROGRAMS,SUCHASVB,C/CORDELPHI,ANDSOONTHOUGHTHETECHNOLOGYOFCGIISDEVELOPEDANDPOWERFUL,BECAUSEOFDIFFICULTIESINPROGRAMMING,ANDLOWEFFICIENCY,MODIFYCOMPLEXSHORTCOMINGS,ITISGRADUALLYBEINGREPLACEDBYTHETRENDOFALLTHENEWTECHNOLOGY,JSP/SERVLETWITHMOREEFFICIENTANDEASYTOPROGRAM,MOREPOWERFUL,MORESECUREANDHASAGOODPORTABILITY,THEYHAVEBEENMANYPEOPLEBELIEVETHATTHEFUTUREISTHEMOSTDYNAMICSITEOFTHEFUTUREDEVELOPMENTOFTECHNOLOGYSIMILARTOCGI,SERVLETSUPPORTREQUEST/RESPONSEMODELWHENACUSTOMERSUBMITAREQUESTTOTHESERVER,THESERVERPRESENTEDTHEREQUESTSERVLET,SERVLETRESPONSIBLEFORHANDLINGREQUESTSANDGENERATEARESPONSE,ANDTHENGAVETHESERVER,ANDTHENFROMTHESERVERSENTTOTHECUSTOMERANDTHECGIISDIFFERENT,SERVLETNOTGENERATEANEWPROCESS,BUTWITHHTTPSERVERATTHESAMEPROCESSITTHREADSTHROUGHTHEUSEOFTECHNOLOGY,REDUCETHESERVERCOSTSSERVLETHANDLINGOFTHEREQUESTPROCESSISTHISWHENRECEIVEDFROMTHECLIENTSREQUEST,CALLINGSERVICEMETHODS,THEMETHODOFSERVLETARRIVALOFTHEFIRSTJUDGEMENTISWHATTYPEOFREQUESTGET/POST/HEAD,THENCALLSTHEAPPROPRIATETREATMENTDOGET/DOPOST/DOHEADANDGENERATEARESPONSEALTHOUGHSUCHACOMPLEX,INFACT,SIMPLYSAIDTOSERVLETISAJAVACLASSANDTHEGENERALCATEGORYOFTHEDIFFERENCEISTHATTHISTYPEOPERATINGINASERVLETCONTAINER,WHICHCANPROVIDESESSIONMANAGEMENTANDTARGETEDLIFECYCLEMANAGEMENTSOTHATWHENYOUUSETHESERVLET,YOUCANGETALLTHEBENEFITSOFTHEJAVAPLATFORM,INCLUDINGTHESAFETYOFTHEMANAGEMENT,USEJDBCACCESSTHEDATABASEANDCROSSPLATFORMCAPABILITYMOREOVER,SERVLETUSINGTHREAD,ANDCANDEVELOPMOREEFFICIENTWEBAPPLICATIONSJSPTECHNOLOGYISAKEYJ2EETECHNOLOGY,ITATAHIGHERLEVELOFABSTRACTIONOFASERVLETITALLOWSCONVENTIONALSTATICANDDYNAMICHTMLCONTENTGENERATEDBYCOMBININGANHTMLPAGELOOKSLIKE,BUTASASERVLETTORUNTHEREAREMANYCOMMERCIALAPPLICATIONSERVERSUPPORTJSPTECHNOLOGY,SUCHASBEAWEBLOGIC,IBMWEBSPHERE,JRUN,ANDSOONJSPANDSERVLETUSEMORETHANSIMPLEIFYOUHAVEAJSPSUPPORTFORWEBSERVERS,ANDAJSPDOCUMENT,YOUCANPUTITFANGDAOANYSTATICHTMLFILESCANBEPLACED,DONOTHAVETOCOMPILE,DONOTHAVETOPACK,DONOTHAVETOCLASSPATHSETTINGS,YOUCANVISITASORDINARYWEBITDIDVISIT,THESERVERWILLAUTOMATICALLYHELPYOUTODOOTHERWORKJSPDOCUMENTLOOKSLIKEANORDINARYSTATICHTMLDOCUMENT,BUTINSIDECONTAINSANUMBEROFJAVACODEITUSESJSPTHESUFFIX,USEDTOTELLTHESERVERTHISDOCUMENTINNEEDOFSPECIALTREATMENTWHENWEVISITAJSPPAGE,THEDOCUMENTWILLFIRSTBETRANSLATEDINTOAJSPENGINEJAVASOURCEFILES,ISACTUALLYASERVLET,ANDCOMPILER,ANDTHEN,LIKEOTHERSERVLET,FROMSERVLETENGINETOHANDLESERVLETENGINEOFTHISTYPELOADING,HANDLINGREQUESTSFROMCUSTOMERS,ANDTHERESULTSRETURNEDTOTHECUSTOMER,ASSHOWNBELOWFIGURE1CALLINGTHEPROCESSOFJSPPAGESAFTERANOTHERVISITTHISPAGETOTHECUSTOMER,ASLONGASTHEPAPERTHEREHAVEBEENNOCHANGES,JSPENGINEHASBEENLOADEDDIRECTLYCALLTHESERVLETIFYOUHAVEALREADYBEENMODIFIED,ITWILLBEONCEAGAINTHEIMPLEMENTATIONOFTHEABOVEPROCESS,TRANSLATE,COMPILEANDLOADINFACT,THISISTHESOCALLED“FIRSTPERSONTOPUNISHMENT“BECAUSEWHENTHEFIRSTVISITTOTHEIMPLEMENTATIONOFASERIESOFTHEABOVEPROCESS,SOWILLSPENDSOMETIMEAFTERSUCHAVISITWOULDNOTJAVASERVLETSOFFERAPOWERFULAPITHATPROVIDESACCESSTOALLTHEINFORMATIONABOUTTHEREQUEST,THESESSION,ANDTHEAPPLICATIONCOMBININGJSPWITHSERVLETSLETSYOUCLEARLYSEPARATETHEAPPLICATIONLOGICFROMTHEPRESENTATIONOFTHEAPPLICATIONINOTHERWORDS,ITLETSYOUUSETHEMOSTAPPROPRIATECOMPONENTTYPEFORTHEROLESOFMODEL,VIEWANDCONTROLLERSERVLETS,FILTERS,ANDLISTENERSASERVLETISAJAVACLASSTHATEXTENDSASERVERWITHFUNCTIONALITYFORPROCESSINGAREQUESTANDPRODUCINGARESPONSEITSIMPLEMENTEDUSINGTHECLASSESANDINTERFACESDEFINEDBYTHESERVLETAPITHEAPICONSISTSOFTWOPACKAGESTHEJAVAXSERVLETPACKAGECONTAINSCLASSESANDINTERFACESTHATAREPROTOCOLINDEPENDENT,WHILETHEJAVAXSERVLETHTTPPACKAGEPROVIDESHTTPSPECIFICEXTENSIONSANDUTILITYCLASSESWHATMAKESASERVLETASERVLETISTHATTHECLASSIMPLEMENTSANINTERFACENAMEDJAVAXSERVLETSERVLET,EITHERDIRECTLYORBYEXTENDINGONEOFTHESUPPORTCLASSESTHISINTERFACEDEFINESTHEMETHODSUSEDBYTHEWEBCONTAINERTOMANAGEANDINTERACTWITHTHESERVLETASERVLETFORPROCESSINGHTTPREQUESTSTYPICALLYEXTENDSTHEJAVAXSERVLETHTTPHTTPSERVLETCLASSTHISCLASSIMPLEMENTSTHESERVLETINTERFACEANDPROVIDESADDITIONALMETHODSSUITABLEFORHTTPPROCESSINGSERVLETLIFECYCLETHEWEBCONTAINERMANAGESALLASPECTSOFTHESERVLETSLIFECYCLEITCREATESANINSTANCEOFTHESERVLETCLASSWHENNEEDED,PASSESREQUESTSTOTHEINSTANCEFORPROCESSING,ANDEVENTUALLYREMOVESTHEINSTANCEFORANHTTPSERVLET,THECONTAINERCALLSTHEFOLLOWINGMETHODSATTHEAPPROPRIATETIMESINTHESERVLETLIFECYCLEBESIDESTHEDOGETANDDOPOSTMETHODS,THEREAREMETHODSCORRESPONDINGTOTHEOTHERHTTPMETHODSDODELETE,DOHEAD,DOOPTIONS,DOPUT,ANDDOTRACETYPICALLYYOUDONTIMPLEMENTTHESEMETHODSTHEHTTPSERVLETCLASSALREADYTAKESCAREOFHEAD,OPTIONS,ANDTRACEREQUESTSINAWAYTHATSSUITABLEFORMOSTSERVLETS,ANDTHEDELETEANDPUTHTTPMETHODSARERARELYUSEDINAWEBAPPLICATIONITSIMPORTANTTOREALIZETHATTHECONTAINERCREATESONLYONEINSTANCEOFEACHSERVLETTHISMEANSTHATTHESERVLETMUSTBETHREADSAFEABLETOHANDLEMULTIPLEREQUESTSATTHESAMETIME,EACHEXECUTINGASASEPARATETHREADTHROUGHTHESERVLETCODEWITHOUTGETTINGLOSTINDETAILS,YOUSATISFYTHISREQUIREMENTWITHREGARDSTOINSTANCEVARIABLESIFYOUMODIFYTHEREFERENCEDOBJECTSONLYINTHEINITANDDESTROYMETHODS,ANDJUSTREADTHEMINTHEREQUESTPROCESSINGMETHODSCOMPILINGANDINSTALLINGASERVLETTOCOMPILEASERVLET,YOUMUSTFIRSTENSURETHATYOUHAVETHEJARFILECONTAININGALLSERVLETAPICLASSESINTHECLASSPATHENVIRONMENTVARIABLETHEJARFILEISDISTRIBUTEDWITHALLWEBCONTAINERSTOMCATINCLUDESITINAFILECALLEDSERVLETJAR,LOCATEDINTHECOMMON/LIBDIRECTORYONAWINDOWSPLATFORM,YOUINCLUDETHEJARFILEINTHECLASSPATHREADINGAREQUESTONEOFTHEARGUMENTSPASSEDTOTHEDOGETANDDOPOSTMETHODSISANOBJECTTHATIMPLEMENTSTHEHTTPSERVLETREQUESTINTERFACETHISINTERFACEDEFINESMETHODSTHATPROVIDEACCESSTOAWEALTHOFINFORMATIONABOUTTHEREQUESTGENERATINGARESPONSEBESIDESTHEREQUESTOBJECT,THECONTAINERPASSESANOBJECTTHATIMPLEMENTSTHEHTTPSERVLETRESPONSEINTERFACEASANARGUMENTTOTHEDOGETANDDOPOSTMETHODSTHISINTERFACEDEFINESMETHODSFORGETTINGAWRITERORSTREAMFORTHERESPONSEBODYITALSODEFINESMETHODSFORSETTINGTHERESPONSESTATUSCODEANDHEADERSUSINGFILTERSANDLISTENERSTHESERVLETSPECIFICATIONDEFINESTWOCOMPONENTTYPESBESIDESERVLETSFILTERSANDLISTENERSTHESETWOTYPESWEREINTRODUCEDINTHESERVLET23SPECIFICATION,SOIFYOUREUSINGACONTAINERTHATDOESNTYETSUPPORTTHISVERSIONOFTHESPECIFICATION,IMAFRAIDYOUREOUTOFLUCKFILTERSAFILTERISACOMPONENTTHATCANINTERCEPTAREQUESTTARGETEDFORASERVLET,JSPPAGE,ORSTATICPAGE,ASWELLASTHERESPONSEBEFOREITSSENTTOTHECLIENTTHISMAKESITEASYTOCENTRALIZETASKSTHATAPPLYTOALLREQUESTS,SUCHASACCESSCONTROL,LOGGING,ANDCHARGINGFORTHECONTENTORTHESERVICESOFFEREDBYTHEAPPLICATIONAFILTERHASFULLACCESSTOTHEBODYANDHEADERSOFTHEREQUESTANDRESPONSE,SOITCANALSOPERFORMVARIOUSTRANSFORMATIONSONEEXAMPLEISCOMPRESSINGTHERESPONSEBODYIFTHEACCEPTLANGUAGEREQUESTHEADERINDICATESTHATTHECLIENTCANHANDLEACOMPRESSEDRESPONSEAFILTERCANBEAPPLIEDTOEITHERASPECIFICSERVLETORTOALLREQUESTSMATCHINGAURLPATTERN,SUCHASURLSSTARTINGWITHTHESAMEPATHELEMENTSORHAVINGTHESAMEEXTENSIONLISTENERSLISTENERSALLOWYOURAPPLICATIONTOREACTTOCERTAINEVENTSPRIORTOSERVLET23,YOUCOULDHANDLEONLYSESSIONATTRIBUTEBINDINGEVENTSTRIGGEREDWHENANOBJECTWASADDEDORREMOVEDFROMASESSIONYOUCOULDDOTHISBYLETTINGTHEOBJECTSAVEDASASESSIONATTRIBUTEUSINGTHEHTTPSESSIONSETATTRIBUTEMETHODIMPLEMENTTHEHTTPSESSIONBINDINGLISTENERINTERFACEWITHTHENEWINTERFACESINTRODUCEDINTHE23VERSIONOFTHESPECIFICATION,YOUCANCREATELISTENERSFORSERVLETCONTEXTANDSESSIONLIFECYCLEEVENTSASWELLASSESSIONACTIVATIONANDPASSIVATIONEVENTSUSEDBYACONTAINERTHATTEMPORARILYSAVESSESSIONSTATETODISKORMIGRATESASESSIONTOANOTHERSERVERANEWSESSIONATTRIBUTEEVENTLISTENERALSOMAKESITPOSSIBLETODEALWITHATTRIBUTEBINDINGEVENTSFORALLSESSIONSINONEPLACE,INSTEADOFPLACINGINDIVIDUALLISTENEROBJECTSINEACHSESSIONTHENEWTYPESOFLISTENERSFOLLOWTHESTANDARDJAVAEVENTMODELINOTHERWORDS,ALISTENERISACLASSTHATIMPLEMENTSONEORMOREOFTHELISTENERINTERFACESTHEINTERFACESDEFINEMETHODSTHATCORRESPONDTOEVENTSTHELISTENERCLASSISREGISTEREDWITHTHECONTAINERWHENTHEAPPLICATIONSTARTS,ANDTHECONTAINERTHENCALLSTHEEVENTMETHODSATTHEAPPROPRIATETIMESINITIALIZINGSHAREDRESOURCESUSINGALISTENERBEANSLIKETHISTYPICALLYNEEDTOBEINITIALIZEDBEFORETHEYCANBEUSEDFORINSTANCE,THEYMAYNEEDAREFERENCETOADATABASEORSOMEOTHEREXTERNALDATASOURCEANDMAYCREATEANINITIALINFORMATIONCACHEINMEMORYTOPROVIDEFASTACCESSEVENTOTHEFIRSTREQUESTFORDATAYOUCANINCLUDECODEFORINITIALIZATIONOFTHESHAREDRESOURCESINTHESERVLETANDJSPPAGESTHATNEEDTHEM,BUTAMOREMODULARAPPROACHISTOPLACEALLTHISCODEINONEPLACEANDLETTHEOTHERPARTSOFTHEAPPLICATIONWORKONTHEASSUMPTIONTHATTHERESOURCESAREALREADYINITIALIZEDANDAVAILABLEANAPPLICATIONLIFECYCLELISTENERISAPERFECTTOOLFORTHISTYPEOFRESOURCEINITIALIZATIONTHISTYPEOFLISTENERIMPLEMENTSTHEJAVAXSERVLETSERVLETCONTEXTLISTENERINTERFACE,WITHMETHODSCALLEDBYTHECONTAINERWHENTHEAPPLICATIONSTARTSANDWHENITSHUTSDOWNPICKINGTHERIGHTCOMPONENTTYPEFOREACHTASKTHEPROJECTBILLBOARDAPPLICATIONINTRODUCEDISAFAIRLYCOMPLEXAPPLICATIONHALFTHEPAGESAREPURECONTROLLERANDBUSINESSLOGICPROCESSING,ITACCESSESADATABASETOAUTHENTICATEUSERS,ANDMOSTPAGESREQUIREACCESSCONTROLINREALLIFE,ITWOULDLIKELYCONTAINEVENMOREPAGES,FORINSTANCE,PAGESFORACCESSTOASHAREDDOCUMENTARCHIVE,TIMESCHEDULES,ANDASETOFPAGESFORADMINISTRATIONASTHEAPPLICATIONEVOLVES,ITMAYBECOMEHARDTOMAINTAINASAPUREJSPAPPLICATIONITSEASYTOFORGETTOINCLUDETHEACCESSCONTROLCODEINNEWPAGESTHI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的线程来执行。如果只在INIT（）和DESTROY（）方法中修改参考的对象，而且只在请求处理方法中读取他们，那么不用丧失任何细节就可以满足关于实例变量的这个要求。编译和安装SERVLET要编译SERVLET，必须首先确保JAR文件包含着CLASSPATH环境变量中所有SERVLETAPI类。该JAR文件将随所有的WEB容器一起发布。TOMCAT中包含了一个名为SERVLETJAR的JAR文件，位于COMMON/LIB目录中。在WINDOWS平台中，应在CLASSPATH中包含JAR文件。读取请求传递到DOGET（）和DOPOST（）方法的参数之一是实现了HTTPSERVLETREQUEST接口的对象。该接口定义的方法可提供对关于请求的许多信息的访问。生成应答除应答对象之外，容器还将实现HTTPSERVLETREQUEST接口的对象作为ICANSHU传递给DOGET（）和DOPOST（）方法。该接口定义了为应答行为体获取数序程序或流的方法。它还定义了设置应答状态代码和首部的方法。使用过滤器和监听器SERVLET规范SERVLET内定义了两种组件类型过滤器和监听器。这两种类型是在SERVLET23规范中引入的，因此，如果你使用的是不支持该版本规范的容器，恐怕就不能继续学习了。过滤器过滤器是一种组件，可以解释对SERVLET、JSP页面或静态页面的请求以及发送给客户端之前的应答。这样可以很容易地将应用于所有请求的任务集中在一起，例如访问控制、登录和内容的开销或应用提供的服务等。过滤器对请求与应答的行为体和首部具有完全访问权限，因此还可以执行各种转换。例如，如果ACCEPTLANGUAGE请求首部指出客户端可以处理压缩的应答，那么过滤器就可以压缩应答的行为体。过滤器可以应用在特定SERVLET上，或匹配某种URL模式的所有请求上，例如以相同的路径元素开头或具有相同扩展名的URL。监听器监听器允许应用程序对特定事件做出回应。SERVLET23之前，只能处理会话属性绑定事件（在添加对象或从会话中删除对象时）。实现监听器的方式是用保存为会话属性（使用HTTPSESSIONSETATTRIBUTE方法）的对象实现HTTPSESSIONBINDINGLISTENER接口。随着SERVLET规范的23版本中新接口的引入，可以为