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1、学专班姓学英文科技文献翻译院：电子与自动化学院业：电子信息工程级：电子1201名：李晓鹏号：201215001:英文原文AndroidApplicationFundamentalsAndroidapplicationsarewrittenintheJavaprogramminglanguage・TheAndroidSDKtoolscompilethecode—alongwithanydataandresourcefiles—intoanAndroidpackage,anarchivefilewith
2、an・apksuffix・Allthecodeinasingle・apkfileisconsideredtobeoneapplicationandisthefilethatAndroid-powereddevicesusetoinstalltheapplication.Onceinstalledonadevice,eachAndroidapplicationlivesinitsownsecuritysandbox:TheAndroidoperatingsystemisamulti-userLinux
3、systeminwhicheachapplicationisadifferentuser・Bydefault,thesystemassignseachapplicationauniqueLinuxuserID(theIDisusedonlybythesystemandisunknowntotheapplication)・ThesystemsetspermissionsforallthefilesinanapplicationsothatonlytheuserIDassignedtothatappli
4、cationcanaccessthem.Eachprocesshasitsownvirtualmachine(VM),soanapplication'scoderunsinisolationfromotherapplications.Bydefault,everyapplicationrunsinitsownLinuxprocess・Androidstartstheprocesswhenanyoftheapplication，scomponentsneedtobeexecuted,thenshuts
5、downtheprocesswhenit'snolongerneededorwhenthesystemmustrecovermemoryforotherapplications.Inthisway,theAndroidsystemimplementstheprincipleofleastprivilege・Thatis,eachapplication,bydefauIt,hasaccessonlytothecomponentsthatitrequirestodoitsworkandnomore・Th
6、iscreatesaverysecureenvironmentinwhichanapplicationcannotaccesspartsofthesystemforwhichitisnotgivenpermission.However,therearewaysforanapplicationtosharedatawithotherapplicationsandforanapplicationtoaccesssystemservices:It'spossibletoarrangefortwoappli
7、cationstosharethesameLinuxuserID,inwhichcasetheyareabletoaccesseachother'sfiles・Toconservesystemresources,applicationswiththesameuserIDcanalsoarrangetoruninthesameLinuxprocessandsharethesameVM(theapplicationsmustalsobesignedwiththesamecertificate)・Anap
8、plicationcanrequestpermissiontoaccessdevicedatasuchastheuser'scontacts,SMSmessages,themountablestorage(SDcard),camera,Bluetooth,andmore・Allapplicationpermissionsmustbegrantedbytheuseratinstalltime・ThatcoversthebasicsregardinghowanAndroi
