应用程序基础-外文翻译

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1、ApplicationFundamentalsAbstract:AndroidapplicationsarewrittenintheJavaprogramminglanguageandtheapplicationcomponentshavefourtypesofapplicationcomponents.BeforetheAndroidsystemcanstartanapplicationcomponent,thesystemmustknowthatthecomponentexistsbyreadingtheapplication'sAndroidMani

2、fest.xmlfile(the"manifest"file).AnAndroidapplicationiscomposedofmorethanjustcode—itrequiresresourcesthatareseparatefromthesourcecode,suchasimages,audiofiles,andanythingrelatingtothevisualpresentationoftheapplication.Keywords:Java;applicationcomponents;manifest;source;From:http://d

3、eveloper.android.com/guide/topics/fundamentals.htmlAndroidapplicationsarewrittenintheJavaprogramminglanguage.TheAndroidSDKtoolscompilethecode—alongwithanydataandresourcefiles—intoanAndroidpackage,anarchivefilewithan.apksuffix.Allthecodeinasingle.apkfileisconsideredtobeoneapplicati

4、onandisthefilethatAndroid-powereddevicesusetoinstalltheapplication.Onceinstalledonadevice,eachAndroidapplicationlivesinitsownsecuritysandbox:lTheAndroidoperatingsystemisamulti-userLinuxsysteminwhicheachapplicationisadifferentuser.lBydefault,thesystemassignseachapplicationauniqueLi

5、nuxuserID(theIDisusedonlybythesystemandisunknowntotheapplication).ThesystemsetspermissionsforallthefilesinanapplicationsothatonlytheuserIDassignedtothatapplicationcanaccessthem.lEachprocesshasitsownvirtualmachine(VM),soanapplication'scoderunsinisolationfromotherapplications.lBydef

6、ault,everyapplicationrunsinitsownLinuxprocess.Androidstartstheprocesswhenanyoftheapplication'scomponentsneedtobeexecuted,thenshutsdowntheprocesswhenit'snolongerneededorwhenthesystemmustrecovermemoryforotherapplications.Inthisway,theAndroidsystemimplementstheprincipleofleastprivile

7、ge.Thatis,eachapplication,bydefault,hasaccessonlytothecomponentsthatitrequirestodoitsworkandnomore.Thiscreatesaverysecureenvironmentinwhichanapplicationcannotaccesspartsofthesystemforwhichitisnotgivenpermission.However,therearewaysforanapplicationtosharedatawithotherapplicationsan

8、dforanapplicationtoaccesssystemse