最新安卓系统与IOS系统比较毕业英文文献翻译.docx

最新安卓系统与IOS系统比较毕业英文文献翻译.docx

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最新安卓系统与IOS系统比较毕业英文文献翻译

ESEP2011:

9-10December2011,Singapore

AnAnalysisandComparisonofOpenandClosedMobile

Platforms

Androidvs.iPhone

YingluZOUa,∗,HaoWUb,JianxinHUANGa,b

aInformationEngineeringCollege,7JianXueRoad,JinShuiDistrict,ZhengZhou,450001,China

Abstract

WiththereleaseofAndroid2.2FroyoandiPhone4,thewarbetweenopenandclosedmobileplatformstendstobefiercer.Beingtherepresentativesofthetwoparties,FroyoandiOS4arequitedifferentatsystemframework,newfeature,applicationmarketandintegrationmodel.AccordingtothecompanyspiritsofGoogleandApple,wedosomeanalysesandcomparisonsoftheabovepoints,explainthedifferencesofAndroidandiPhonefromtheshallowertothedeeper,thenconcludethecharacteristicsofopenandclosedmobileplatforms,aimingatprovidinganobjectivereferenceforresearchersofmobileplatforms,helpingthemseeclearerintomobileindustry.Asaresult,bothFroyoandiOS4havetheiradvantagesanddisadvantages,stilltheyarefarfrombeingperfect,there’sroomforfurtherimprovement.

Keywords:

Android；iPhone；Froyo；iOS4；smartphone；mobileplatform

1.Introduction

Inrecentyears,thepopularityofsmartphonekeptgoingup.Moreandmoresmartphonesaresoldandalotofpeopleareembracingthem.Smartphonesbroughtgreatconveniencetousers,aswellcreatedopportunitiesforsmartphoneresearchers.That’stosay,thewidespreadofsmartphonesbenefitedbothsides.Atthesametime,developingofsmartphoneOSbecomesoneofthesmartestindustry.TobeasmartphoneOS,thesystemshould:

1.ProvideserviceslikeaPC.2.WorkwithaGPUforbettervisualeffects.3.AllowtheusertosurfonInternetfreely.Andapparently,there’realsosomeweaknesses:

1.Limitedbattery.2.PoorCPUperformanceagainstPCCPU.3.Smallstorage.4.TheuseofRAMmayleadstolossofdatawhenthephonerunsoutofbattery

Nowthe2giantsofsmartphoneOSareAndroidandiPhoneOS.Ononeside,AndroidisbasedonLinuxkernelandDalvikvirtualmachine,anditisopensourced.TheupperlayerofAndroidisJavabased,allowingdeveloperstodevelopAndroidapplicationswithGoogleSDKandselltheirsoftwareinAndroidMarket.Ontheotherside,iPhoneOS,whichbasesonUnixkernelandDarwinmodelbutisclosedsourced,evolvesfromMacOSXandisthedefaultOSofiPhone,iPodTouchandiPad.ObjectiveCbasedsoftwarecanruniniPhoneOS,andjustlikeAndroid,youcandevelopyourowniPhoneapplicationsanduploadthemontoApple’s‘AppStore’forsale[1][2][3][4].

BycomparingthelatestAndroidandiPhoneOS,Android2.2FroyoandiOS4,wecantakeaglimpseatthemainfeatureofopenandclosedsmartphoneOSs.Whilethe2OSsaredesignedinratherdifferentmentalityandfunctionality,it’salittleearlytotellwhichoneisbetter.

2.SmartPhoneOS

2.1.Android

ThesystemarchitectureofAndroidconsistsof5layers,whichareLinuxKernel,AndroidRuntime,Libraries,ApplicationFrameworkandApplications,frombottomtotop.

Androidprovidescoreserviceslikesecurity,memorymanagement,processmanagement,networkstackanddrivers,basingonLinux2.6.Beingtheabstractlayerbetweensoftwareandhardware,thelayerofLinuxKernelhidestheimplementingdetailsofhardwareandprovidesintegratedservicesforupperlayer.

DalvikvirtualmachineandJavacorelibrariesareincludedinthelayerofAndroidRuntime,providingmostfunctionsinJavacorelibraries.

ThelayerofLibrariescontainsaclassofC/C++librariesforAndroidcomponents.ThoselibrariesareintegratedbythelayerofApplicationFrameworkandthenprovidedtodevelopers.

ThelayerofApplicationFrameworkprovidesallkindsofmodulesforprograminitializationtosimplifytheuseofcomponents,allowingdevelopersdowhatevertheywantandprovideservicesforothersoftwares,underthelimitationofsecurity,ofcourse.

MainstreamapplicationsarelocatedinthelayerofApplication,includinge-mail,SMS,calendar,Googlemap,Webbrowserandcontacts.Usersinteractdirectlywiththislayer[1][2].

ThelatestversionofAndroid,Android2.2Froyo,putsonsomenewfeatures.Theyare:

1.SupportFlash10.1,enablesusertowatchflashonthephone.2.V8JavaScriptengineinwebbrowserleadstofasterInternetdatatransportation.3.Bigadvanceinnetworksharing.Youcanusethephoneasa3GNIC,orconvert3GsignaltoWi-Fi.4.Automaticallysoftwareupdate.5.SoftwarescanbesetupinSDcardtoextendfilestorages.

2.2.iPhone

iPhoneOSisconsistof4abstractlayers:

CoreOS,CoreService,MediaandCocoaTouchrespectively.

LayersofCoreOSandCoreServicearedesignedinClanguagetohandlecoresystemservices,enablingdeveloperstoperformfileaccess,socketscallinganddatahandling.CFNetworkandSQLitearealsopartsofthese2layers.

ThelayerofMedia,accordingtoitsname,thislayerisusedtocontrolvideoandaudio,aswellhandle2Dand3Dimages.TheOpenGL-ESQuratzpartofthelayeriscodedwithClanguage,whilethepartofCore-AudioandCore-AnimationisObjectiveCbased.

ThelayerofCocoaTouchbuildsabasicframeworkforallkindsofprogramsiniPhone.MostprogramsruninCocoaTouchlayer,andit’ssurelyObjectiveCbased[3][4].

ThelatestiPhoneOSisiOS4.Itincludesthefollowingnewfeatures:

1.Softwareclassification.This

featureenablesusertoplacesortedsoftwaresintodifferentdocuments,makingitclearertomanage.2.Emailintegration.Oneaccountisforalle-mailsfromdifferentproviders.3.iBook,originallyfromiPad,isbuiltiniOS.4.AbrandnewAppleGameCentermakesiPhoneatremendousentertainmentplatform.

2.3.Androidvs.iPhone

Beingthetop2smartphoneOSs,we’resurethatbothAndroidandiPhonehavetheirownadvantagesanddisadvantages.Nowlet’stakealookateachofthem,andseewhatuniquefeaturetheyhave.

Android2.2Froyofullysupportmultitask,whichmeansyoucanlistentomusicwhilewritingblog.AndiOS4,officiallyannouncedtobe‘multitasked’,isinfactaplayofconcept.OnlyafewofsoftwareswhichareauthorizedbyApplecanrun‘simultaneously’,whoseprincipleismucheasierthatmultitask:

whenanapplicationisswitchedout,itscurrentstateissavedandthenthesystemjustclosesit.Andwhenit’sswitchedin,we’rebacktotheprevioussnapshot[5][6][7].

DuringthepublicationofAndroid2.2Froyo,Googleannouncedithas‘themostfluentwebbrowser’,becausetheuseofV8JavaScriptengine.V8isabrandnewengine,designedforrunningbigsizeJavaScriptapplication.Insomekindoftests,V8ismuchfasterthanJScriptfromInternetExplorer,SpiderMonkeyfromFirefoxandJavaScriptCorefromSafari.Italloweto3keypartsofV8,they’refastattributeaccess,dynamiccodegeneration,effectivetrashcleaning.

2.3.1.FastAttributeAccess

JavaScriptisakindofdynamiclanguage,whichmeansattributescanbeaddedordeletedatruntime,andthey’refrequentlychanged.MostJavaScriptenginesuseadictionarystylestructuretostoretheattributesofanobject,soitrequiresawholedictionarysearchtofindthepositionofattributesinmemory.It’squiteinefficientandit’sslowerthanJavaandSmalltalk.

Tosolvethisproblem,V8discardeddynamicsearchandrealizeditinadifferentway:

Createhiddenclassesforobjectsdynamically.InJavaScript,everytimewhenwe’readdinganewattributetoanobject,wecreateasubclasswiththenewattributefromahiddenclassasthesuperclass.It’sarecursivecourseandtheaboveperformancehappensonlyoncewhenwefirstdothis.Laterwejustusetheprevioushiddensubclasswhenwe’reinthesamesituation.Sothere’snoneedtorepeatoperationandcreateadictionary.Thisleadstothesaveoftimeandenergy,aswellmakeiteasierfortheimplementationofclassoptimizationandinnercache[4].

2.3.2.DynamicCodeGeneration

WhenJavaScriptisrunningfortheveryfirsttime,V8translateitdirectlyintolocalmachinecode,ratherthanexplainittobytecode.Attributeaccessisdonebyinnercache,whichisoftentranslatedintoinstructionsbyV8atruntime.

Whenitcomestothecodewherecertainobjectisaccessed,V8triestofindthecurrenthiddenclass.Meanwhile,V8assumesthatallobjectsinthesnippetaredescribedbythesamehiddenclass,soV8willmodifycorrespondinginnercachetomakethedirectuseofthehiddenclassmoreconvenient.Ifthisassumptioniscorrect,theaccessofattributescanbealldoneinonly1instruction.Evenifthepredictionfails,innercacheismodifiedagainbyV8,whichwon’ttaketoomuchtimeandresource.Whenonehiddenclassissharedbyalotofobjects,theaccessspeedcanbeclosetomostdynamiclanguageaccessspeed.Innercacheandhiddenclass,mixedwithdynamiccodeandclassoptimization,improvetheefficiencyofJavaScriptatalargescale[4].

2.3.3.EffectiveTrashCleaning

V8doesmemoryrecyclesautomatically.Toguaranteethespeedofobjectdistribution,aswellcutthetimeoftrashcleaningandclearfragmentup,V8willinterrupttherunningapplicationwhenperformingtrashcleaning.Mostly,onlyasmallpartofobjectstackisinvolvedintrashcleaningcycle,sotheinterruptioncausedlittle.AlllocationofobjectsandpointersareloggedbyV8,sothesystemwon’ttakeobjectforpointerandmemoryoverflowisavoided[4].

Besides‘themostfluentwebbrowser’,GooglecollaboratedwithAdobeandAndroid2.2FroyofullysupportsFlash.That’stosay,notonlyflashmedia,butallflashwebpagescandisplayperfectlyonAndroid.Tothecontrary,AppleturneddownAdobeandtakeHTML5asiPhone’swebprotocol,makingitunabletoshowsomeflashbasedanimation.

Android2.2Froyoalsoleadsthewayinnetworksharing.SmartphonewithFroyocanbeconnected