翻译文献-3.4.1服务器控件工具箱

外文原文THESERVERCONTROLTOOLBOXATFIRSTGLANCE,THEARRAYOFSERVERCONTROLSINTHETOOLBOXCANBEQUITEOVERWHELMINGNOTONLYDOYOUHAVESTANDARDWEBPAGEELEMENTSTOCHOOSEFROMSUCHASRADIOBUTTONS,HYPERLINKS,ANDDROPDOWNLISTS,BUTOTHERCATEGORIESOFCONTROLSAREALSOAVAILABLESHOWNMINIMIZEDINFIGURE316THATCONTAINEVENMORECONTROLSTHETOOLBOXCHANGESAPPEARANCEDEPENDINGONWHICHTYPEOFPAGEISBEINGEDITED,SOFIGURE316ISTHESTANDARDAPPEARANCEWHENYOUREWORKINGONASPNETPAGESFIGURE316THECATEGORIESOFCONTROLSAVAILABLEAREASFOLLOWSSTANDARDCOMMONCONTROLSTHATMAKEUP90PERCENTOFALLPAGESDATACONTROLSUSEDTOCONNECTTODATASOURCESDATABASESORXMLFILESVALIDATIONCONTROLSTHATCANBEADDEDTOAPAGETOVALIDATEUSERINPUTFOREXAMPLE,TOENSURETHATCERTAINTEXTBOXESCONTAINDATAORTHATDATAHASBEENENTEREDINTHECORRECTFORMATNAVIGATIONCONTROLSUSEDTOPROVIDEASIMPLEANDQUICKSOLUTIONTOMAKINGASITENAVIGABLEFOREXAMPLE,DYNAMICMENUSANDBREADCRUMBSOFHYPERLINKSLOGINASETOFCONTROLSTHATMAKEITSIMPLETOMOVEFROMACOMPLETELYOPENSITETOONETHATHASPERSONALIZEDAREASWEBPARTSCONTROLSTHATMAKEITPOSSIBLETOCREATESHAREPOINTSTYLESITESWITHDRAGANDDROPPABLESECTIONS,KNOWNASWEBPARTS,WHICHENABLETHEUSERTOREARRANGETHEIRVIEWOFASITEHTMLSIMPLEHTMLELEMENTSTHROUGHOUTTHERESTOFTHISBOOK,YOULLBEINTRODUCEDTOMANYOFTHECONTROLSINEACHCATEGORYLATERINTHISCHAPTER,YOUCANPLAYWITHSOMEOFTHENAVIGATIONCONTROLSWHENYOUBUILDSOMEMENUSFORTHEWROXUNITEDSITEWHATARESERVERCONTROLSLETSSTARTFROMFIRSTPRINCIPLESWHENYOUCREATEASIMPLEHTMLPAGEANDSAVEITTOYOURLOCALFILESYSTEM,YOUCANVIEWTHATPAGEINYOURBROWSERBYDOUBLECLICKINGTHEFILETHISISFINEIFYOUREPUTTINGTOGETHERASTATICHTMLSITEANDWANTTOTESTTHEOUTPUT,BUTTHERESNOPOINTINDEVELOPINGAWEBSITETHATUSERSWOULDHAVETODOWNLOADTOVIEWTHATSWHY,WHENAWEBSITEISDEPLOYED,ITISUPLOADEDTOAWEBSERVER,WHICHEVERYONECANACCESSVIAITSURLUNIFORMRESOURCELOCATORWHENTHESITEISHOSTEDONAWEBSERVER,PEOPLECANACCESSTHESITEFROMOTHERMACHINESANDBROWSETHROUGHTHEHTMLPAGESHOWEVER,IFTHESERVERHASTHERIGHTSOFTWAREINSTALLED,YOUCANTHENDOMUCHMORETHANOFFERSTATICHTMLPAGESWHENYOUREQUESTANHTMLPAGE,THESERVERLOOKSUPTHEFILEANDSENDSITTOYOUWHENYOUREQUESTANASPNETPAGEAPAGEWITHTHEFILEEXTENSIONASPX,THESERVERLOOKSUPTHEFILEONITSFILESYSTEMANDREADSTHEFILE,ANDTHENITPERFORMSSOMEPROCESSINGBEFORESENDINGTHERESULTINGPAGEBACKTOYOUTHE“PERFORMSSOMEPROCESSING”BITISTHEMAGICTHATMAKESASPNETWORKTHEEXTRAPROCESSINGTHATTHESERVERPERFORMSINCLUDESTHECAPABILITYTOREADANASPNETPAGEANDCONVERTTHESERVERCONTROLSINTHATPAGEINTOHTMLTHATTHEBROWSERCANUNDERSTANDREMEMBER,YOURBROWSERDOESNTSPEAKASPNETAWEBBROWSERISASIMPLETHINGTHATONLYSPEAKSHTMLANDPOSSIBLYJAVASCRIPTITCANNOTPROCESSASPNETCODETHESERVERREADSTHEASPNETCODEANDPROCESSESIT,CONVERTINGANYTHINGTHATISASPNETSPECIFICTOHTMLANDASLONGASTHEBROWSERSUPPORTSITABITOFJAVASCRIPT,ANDSENDSTHEFRESHLYGENERATEDHTMLBACKTOTHEBROWSERTHEPROCESSOFCONVERTINGASPNETCODETOHTMLISHOWSERVERCONTROLSWORKYOUCANHAPPILYCREATEPAGESTHATCONTAINSERVERCONTROLSWHENYOUAREDEVELOPINGTHESOURCEASPXPAGE,YETTHEBROWSERTHATREQUESTSTHATPAGEFROMTHEWEBSERVERWILLONLYRECEIVEHTMLANDJAVASCRIPTSEEFIGURE317THISISAKEYCONCEPTTOUNDERSTAND,ANDTHEPROCESSISDISCUSSEDINMOREDETAILINCHAPTER6YOUCANSEEHOWTHISWORKSWITHTHEAIDOFASIMPLEEXAMPLETHEFOLLOWINGTRYITOUTISAREALLYSIMPLEEXAMPLETODEMONSTRATETHEDIFFERENCESBETWEENTHEASPNETCODEANDHTMLCODE1REOPENTHECHAPTER03WEBSITE2RIGHTCLICKTHEROOTOFTHEWEBSITEANDSELECTADDNEWITEM3INTHEDIALOGBOXTHATAPPEARSSHOWNINFIGURE318,SELECTWEBFORM,CALLTHEPAGESERVERCONTROLSASPX,SELECTYOURPREFERREDLANGUAGEFROMTHEDROPDOWNLIST,ANDLEAVEBOTHOFTHECHECKBOXESUNCHECKEDFIGURE3184IFYOUARENOTALREADYINDESIGNVIEW,SWITCHINTOTHATMODEANDDOUBLECLICKATEXTBOXCONTROLFROMTHESTANDARDSECTIONOFTHECONTROLTOOLBOXONTHELEFTSEEFIGURE319TOADDITTOTHEMAINBODYOFTHEPAGEFIGURE3195YOUREACTUALLYREADYTOVIEWTHEPAGENOW,SORIGHTCLICKONTHEPAGEANDSELECTVIEWINBROWSERYOURBROWSERSHOULDSTARTANDDISPLAYTHEPAGESHOWNINFIGURE320FIGURE320NOTETHATTHENUMBERDISPLAYEDINTHEADDRESSBARAFTERTHEWORD“LOCALHOST”ISAFAIRLYRANDOMNUMBERTHATISGENERATEDWHENEVERYOUFIRSTREQUESTASERVERSIDEPAGEFROMAPROJECTHOWITWORKSINTHISEXAMPLE,YOUONLYADDEDASINGLESERVERCONTROLTOANASPNETPAGEANDVIEWEDTHEPAGEINTHEBROWSERITSNOTEXACTLYTHEMOSTEXCITINGEXAMPLEINTHEWORLD,BUTTHEPOINTISTOSEEHOWSERVERSIDECODEISCHANGEDINTOCLIENTSIDECODECLICKTHEVIEWMENUINTHEBROWSERANDSELECTVIEWSOURCEYOUSHOULDSEETHECODESHOWNINFIGURE321APPEARWITHINNOTEPADFIGURE321THISCODEISTHECLIENTSIDECODETHERENDEREDOUTPUTOFTHEPAGECOMPARETHISWITHTHEORIGINALCODERETURNTOVWDANDCLICKTHESOURCEVIEWOFTHEPAGESEEFIGURE322FIGURE322NOTETHELINESTHATDESCRIBETHECONTROLWITHTHEIDOFTEXTBOX1HEREARETHOSELINES,ASTHEYAPPEARINTHEORIGINALSOURCECODEFORTHEPAGEANDHEREISTHEEQUIVALENTLINEINTHERENDEREDSOURCECODENOTICETHATTHEORIGINALTEXTBOX1CONTROLHASBEENCONVERTEDFROMANASPNETCONTROLTOANHTMLELEMENTTHESERVERRECEIVEDTHEREQUESTFORTHEPAGEANDWASABLETOGLEAN,FROMTHEORIGINALREQUEST,THATTHEBROWSERCOULDUNDERSTANDHTML,SOTHESERVERPRODUCEDANHTMLVERSIONOFTHECONTROLALONGWITHTHERESTOFTHEPAGEBACKTOTHEBROWSERTHEBROWSERTHENDOESTHELEGWORKINCONVERTINGTHATHTMLCODETOAVIEWABLEWEBPAGESOURCEVIEWINVWDVISUALWEBDEVELOPERHASTWOMAINMODESWHENITCOMESTOBUILDINGANDEDITINGPAGESTHEDESIGNVIEWISONETHATYOUVESPENTALITTLEWHILEWORKINGINNOW,ANDITSTHEDESIGNVIEWTHATYOULLCONCENTRATEONUSINGWHEREYOUCANINTHISBOOKTOAVOIDHAVINGTOTYPETOOMUCHCODEHOWEVER,SOURCEVIEWISREALLYUSEFULFOREDITINGAPAGEANDFIXINGNAGGINGPROBLEMS,SOITSWORTHWHILETAKINGALOOKATTHISNOWANDGAININGSOMEFAMILIARITYADDANOTHERCONTROLTOTHEPAGEYOUWEREJUSTWORKINGON,THISTIMEINSOURCEVIEW1HEADBACKINTOVWDANDENSURETHATYOUAREINSOURCEVIEWFORTHESERVERCONTROLSASPXPAGECLICKTHELINKATTHEBOTTOMOFTHEWINDOWTOSWITCHBETWEENDESIGNVIEWANDSOURCEVIEWINTHECODETHATAPPEARS,CLICKTHELINEIMMEDIATELYBELOWTHECODEREPRESENTINGTHETEXTBOXCONTROLTHATYOUADDEDINTHEPREVIOUSEXAMPLE2YOUHAVETWOOPTIONSAVAILABLETOYOUWHENYOUADDSERVERCONTROLSINSOURCEVIEWYOUCANEITHERTYPETHECODE,ORDRAGANDDROPTHECONTROLFROMTHETOOLBOX,MUCHLIKETHETECHNIQUEUSEDINDESIGNVIEWDOITTHEHARDWAYFIRSTSTARTTYPINGTHEFOLLOWINGCODENOTICETHATVWDPRESENTSYOUWITHALISTOFLOCALIMAGESWHENYOUENTERTHEIMAGEURLPROPERTYSEEFIGURE3244ADDONEMORECONTROLTOTHEPAGETHISTIME,ADDITUSINGTHEDOUBLECLICKTECHNIQUEADDABLANKLINEBEFORETHE,POSITIONYOURCURSORINTHISLINE,ANDDOUBLECLICKTHEHYPERLINKCONTROLSEEFIGURE325INTHETOOLBOXTOADDITTOTHEPAGEFIGURE3255YOULLSTILLHAVETOEDITTHISCONTROLBEFOREYOUCANRUNTHEPAGESUCCESSFULLY,SOPOSITIONYOURCURSORANYWHEREWITHINTHEHYPERLINKSDEFINITIONANDTHENCASTYOUREYEOVERTOTHEPROPERTIESPANEONTHERIGHTIFITISHIDDEN,ASINFIGURE325,YOUWILLNEEDTOPOPITOUTFROMTHESIDEBYHOVERINGYOURMOUSEOVERTHEPROPERTIESTABATTHERIGHTHANDEDGEOFYOURSCREEN,ORSELECTVIEWPROPERTIESWINDOWNOTICEAPROPERTYCALLEDNAVIGATEURLNEARTHEBOTTOMOFTHELISTOFPROPERTIESENTERHTTP/WWWWROXUNITEDNETASTHEVALUEFORTHISPROPERTYANDPRESSENTERTAKEALOOKATFIGURE326ANDYOULLNOTICEANEWATTRIBUTEOFTHEHYPERLINKTAGCALLEDNAVIGATEURLAPPEARONTHEPAGEWITHTHEVALUEYOUENTEREDFIGURE3266SWITCHOVERTODESIGNVIEWANDSEEHOWITLOOKSYOULLNOTICEALLTHREECONTROLSONTHEPAGEINONELINEIFYOUDPREFERTHEMTOAPPEARONEBELOWTHEOTHER,SIMPLYTYPEAFTEREACHCONTROLTOADDANHTMLLINEBREAKCHARACTERINSOURCEVIEWYOUMIGHTALSOWANTTOCHANGETHEDISPLAYTEXTOFTHEHYPERLINKCONTROLTHETEXTIMMEDIATELYBEFORETHECLOSINGTAGTOSOMETEXTOFYOURCHOOSINGVISITWROXUNITEDONLINENOTICETHEBARATTHEBOTTOMOFTHESCREENNEXTTOTHEDESIGNANDSOURCEBUTTONSTHERESANORANGEHIGHLIGHTONTHEELEMENTTHATISUNDERNEATHTHECURRENTCURSORPOSITIONSEEFIGURE326THISELEMENTHIERARCHYCHANGESWHENEVERYOUSELECTDIFFERENTELEMENTSINEITHERDESIGNVIEWORSOURCEVIEW7RUNTHEPAGEAGAINANDVIEWTHERESULTS,WHICHAREDEPICTEDINFIGURE327FIGURE327HOWITWORKSINTHISEXAMPLE,YOUGAINEDABITMOREFAMILIARITYWITHTHEDRAGANDDROPMETHODOFPAGEDESIGN,ANDWITHUSINGSOURCEVIEWTOMANUALLYCRAFTPAGESYOUALSOSAWTHATVWDHASLOTSOFFEATURESTHATSPRINGINTOACTIONATDIFFERENTTIMESTOHELPYOUWITHTHISPROCESSHERESAWALKTHROUGHOFTHECODETHATWASGENERATEDINVWDTHEMAINCONTENTREGIONOFTHEPAGEWASSURROUNDEDBYACONTROL,ANDWITHINTHISARETHETHREECONTROLSADDEDTOTHEPAGEVISITWROXUNITEDONLINENOWTAKEALOOKATTHERENDEREDSOURCEWHILETHEPAGEISRUNNINGINTHEBROWSER,SELECTVIEWSOURCEFROMTHEMAINMENUINYOURBROWSER,ANDSEEHOWTHECONTENTSOFTHEHAVEBEENCHANGEDVISITWROXUNITEDONLINEWEBBROWSERSDONTKNOWANYTHINGABOUTASPNETSERVERCONTROLS,SOWHENTHEPAGEISREQUESTED,THEASPNETPROCESSORONTHEWEBSERVERKICKSINANDSTARTSCONVERTINGTHESERVERSIDEELEMENTSINTOSIMPLEHTMLTHATTHEBROWSERISMOREHAPPYTORECEIVETHETEXTBOXCONTROLMAPSSTRAIGHTONTOANHTMLELEMENTTHEIMAGECONTROLISCONVERTEDINTOANELEMENT,BUTNOTICEHOWTHEIMAGEURLATTRIBUTEISCONVERTEDINTOTHESRCATTRIBUTEIMAGEURL“/AZORESCHURCHJPG“THENAMEOFTHEFILEORURLTOTHEIMAGEINTHEIMAGEURLISCONVERTEDTOTHESRCATTRIBUTESRC“AZORESCHURCHJPG“IFTHEFILEISLOCALTOTHEPROJECT,THEFILEISPREFIXEDWITH/ONTHESERVERSIDETHEHYPERLINKCONTROLALSOMAPPEDFAIRLYDIRECTLYTOITSRENDEREDEQUIVALENT,WHERETHENAVIGATEURLISEASILYCONVERTEDTOTHEHREFATTRIBUTEOFTHEATAGINTHISSIMPLEEXAMPLE,YOUDIDNTREALLYGAINALOTFROMUSINGSERVERCONTROLSINSTEADOFCODINGTHEHTML,BUTBEARINMINDTHATTHISPAGEISCOMPLETELYSTATICIFYOUWANTEDTORESPONDTOUSERINPUT,REACTTOEVENTS,OROBTAINDATAFROMADATABASE,YOUWOULDNEEDTOUSESERVERSIDECODESERVERCONTROLSMAKETHEPROCESSOFWORKINGWITHVISUALELEMENTSONTHESERVERPOSSIBLETYPESOFSERVERCONTROLSMANYOFTHEASPNETSERVERCONTROLSTHATEXISTAREASPNETEQUIVALENTSOFHTMLELEMENTS,SOTHEREISATEXTBOX,ABUTTON,AHYPERLINK,ADROPDOWNLIST,ANDSOONTHESECONTROLSLOOKLIKETHEELEMENTSTHATTHEYWILLEVENTUALLYBETURNEDINTO,BUTTHEREISMORETOTHEMTHANTHATEACHCONTROLHASACOMMONSETOFPROPERTIESFOREXAMPLE,THEYALLHAVEANID,ANDCONTROLSSUCHASTHETEXTBOX,LABEL,ANDSOONALLHAVEATEXTPROPERTY,WHICHMAKESITEASIERTOWORKWITHTHESECONTROLSINCODEHAVINGLEARNEDTHEDIFFERENTCATEGORIESOFCONTROLSEARLIERINTHISCHAPTER,YOUCANCONCENTRATEONSOMEOFTHEMOSTCOMMONLY,USEDCONTROLSASYOUTOURTHESERVERCONTROLSYOUCANADDTOASITESTANDARDCONTROLSTHESECONTROLSARETHEWEBEQUIVALENTSOFTHETOOLSTHATYOUENCOUNTERWHENUSINGWINDOWSAPPLICATIONSWEBPAGESTHATINCLUDETHESECONTROLSHAVETHATSTANDARDAPPLICATIONFEELTHATWEREALLFAMILIARWITH,SOTHEPROCESSOFADDINGTHEMTOPAGESISQUICKANDSIMPLEHEREARESOMEOFTHEMOSTCOMMONLYUSEDCONTROLSTEXTBOXCONTROLUSEDFORENTERINGTEXTONAPAGE,COMMONLYSEENONORDERFORMSONSHOPPINGSITES,ORFORLOGGINGINTOASITEBUTTONCONTROLFROMSUBMITTINGANORDERTOCHANGINGPREFERENCESONAWEBSITE,CLICKINGABUTTONONAPAGENORMALLYCAUSESINFORMATIONTOBESENTTOTHESERVER,WHICHREACTSTOTHATINFORMATIONANDDISPLAYSARESULTLABELCONTROLUSEDFORDISPLAYINGSIMPLETEXTINASPECIFI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