应用程序基础-外文翻译

《应用程序基础-外文翻译》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。

1、ApplicationFundamentalsAbstract:AndroidapplicationsarewrittenintheJavaprogramminglanguageandtheapplicationcomponentshavefourtypesofapplicationcomponents.BeforetheAndroidsystemcanstartanapplicationcomponent,thesystemmustknowthatthecomponentexistsbyreadingtheapplication^AndroidManif

2、est.xmlfile(the"manifest”file).AnAndroidapplicationiscomposedofmorethanjustcode一itrequiresresourcesthatareseparatefromthesourcecode,suchasimages,audiofiles,andanythingrelatingtothevisualpresentationoftheapplication.Keywords:Java;applicationcomponents;manifest;source;From:http://de

3、veloper.android.com/guide/topics/fundamentals.htmlAndroidapplicationsarewrittenintheJavaprogramminglanguage.TheAndroidSDKtoolscompilethecode一alongwithanydataandresourcefiles一intoanAndroidpackage,anarchivefilewithan.apksuffix.Allthecodeinasingle.apkfileisconsideredtobeoneapplicatio

4、nandisthefilethatAndroid-powereddevicesusetoinstalltheapplication.Onceinstalledonadevice,eachAndroidapplicationlivesinitsownsecuritysandbox:•TheAndroidoperatingsystemisamulti-userLinuxsysteminwhicheachapplicationisadifferentuser.•Bydefault,thesystemassignseachapplicationauniqueLin

5、uxuserID(theIDisusedonlybythesystemandisunknowntotheapplication).ThesystemsetspermissionsforallthefilesinanapplicationsothatonlytheuserIDassignedtothatapplicationcanaccessthem.•Eachprocesshasitsownvirtualmachine(VM)，soanapplicationscoderunsinisolationfromotherapplications.•Bydefau

6、lt,everyapplicationrunsinitsownLinuxprocess.Androidstartstheprocesswhenanyoftheapplication'scomponentsneedtobeexecuted,thenshutsdowntheprocesswhenitsnolongerneededorwhenthesystemmustrecovermemoryforotherapplications.Inthisway,theAndroidsystemimplementstheprincipleofleastprivilege.

7、Thatis,eachapplication,bydefault,hasaccessonlytothecomponentsthatitrequirestodoitsworkandnomore.Thiscreatesaverysecureenvironmentinwhichanapplicationcannotaccesspartsofthesystemforwhichitisnotgivenpermission.However,therearewaysforanapplicationtosharedatawithotherapplicationsandfo

8、ranapplicationtoaccesssystemservi