Android architecture

Android architecture

Android Architecture

• Overview

• Applications

• Application Framework

• Library and Android Runtime

• Linux kernel

Overview

• Set of necessary application

– Core application of Android include: Home, Browser, Camera

• Your ability:

– Create new applications

– Replace default applications

– Use exist applications for your purposes

Ex: your application want to get a picture from camera So call Camera of Android through intent component

Application Framework

• Provide API to create UI

• Provide API to access system services

• Provide API to get resource

• Content provider

Application Framework

• UI API: views

– Typical view: view like Button, EditText,

ListView…

– ViewGroup: extends View but can contain more than one view like LinearLayout,

FrameLayout

– Special View: Android support WebView and MapView:

• WebView do the job of browser

• MapView a special view use google map API

Application Framework

• System services:

– Get system services:

getSystemService(String)

– Total 20 system services

– Some services:

• LocationManager: get GPS location

• PowerManager: controll power

• SensorManager: access sensors

• WifiManager: manage Wifi access

• …

Application Framework

• Resources:

– Resource is non-code file like image, xml…

– Resource include application resource and

system resource:

• Application resource: files in res folder

• System resource: access through R.android

– To access drawable resource of Android, use R.android.drawable.resourcename

– More resource name at http://www.screaming-penguin.com/info/android_drawables/android_drawab les.html

Application Framework

• Content Provider

– Store and retrieve data and make it accessible

to all applications

– Is the only way to communicate between

applications

– Data kept by content provider can be modified by:

• Adding new records

• Adding new values to exist records

• Batch updating exist records

• Deleting exist records

• C/C++ libraries including:

– System C library

– Media libraries: support playback and record many audio and video format including

MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG

– Sureface Manager: manages access to the display subsystem and seamlessly

composites 2D and 3D graphic layers from multiple applications

– LibWebCore: a modern web browser engine which powers both the Android browser and

an embeddable web view

• C/C++ libraries including:

– SGL: the underlying 2D graphics engine

– 3D libraries: an implementation based on OpenGL

ES 1.0 APIs

– SQLite: a powerful and lightweight relational

database engine available to all applications

– FreeType: bitmap and vector font rendering

Android runtime

• Core java libraries

• Dalvik Virtual Machine

– Thread and memory manager – Optimize memory usage

– Run many virtual machine

• Linux kernel with system services:

– Security

– Memory and process management – Network stack

• Provide driver to access hardware:

– Camera

– Display and audio

– Wifi

– …

The end