Android OS课件.ppt

Android Google Maps and other GMS applications Background services and applications allows multi tasking of applications Shared Data and interprocess communication All applications are equal does not discriminate between native and non-native applications allows any applications to be enhanced/reused p2p interdevice application messaging 精品文档 Dalvik VM All applications written in Java and converted to the dalvik executable .dex Every android app runs its own process, with its own instance of the dalvik virtual machine Not a traditional JVM, but a custom VM designed to run multiple instances efficiently on a single device VM uses linux kernel to handle low-level functionality incl. security, threading, process and memory management 精品文档 Application Framework Rich, extensible set of Views apps can inclused lists, grids, text boxes, buttons, web browser Content Providers allows data access from other applications or share own data Resource Manager access to localized strings, graphics, layout files Notification Manager enables custom alerts to be displayed in status bar Activity Manager Manages lifecycle of applications and provides navigation backstack 精品文档 Application Fundamentals Activities application presentation layer Services invisible components, update data sources, visible activities, trigger notifications perform regular processing even when app is not active or invisible Content Providers shareable data store Intents message passing framework broadcase messages system wide, for an action to be performed Broadcast receivers consume intent broadcasts lets app listen for intents matching a specific criteria like location Notifications Toast notification Status Bar Notification Dialog notification 精品文档 Applications All apps (native and 3rd party) are written using the same APIs and run on the same run time executable All apps have APIs for hardware access, location-based services, support for background services, map-based activities, 2D and 3D graphics. Ap