Android OS.doc
Transcript of Android OS.doc
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ABSTRACT
The unveiling of the Android platform on was announced with the
founding of the Open Handset Alliance, a consortium of 48 hardware, software, and
telecom companies devoted to advancing open standards for mobile devices. Google
has made most of the Android platform available under the Apache free-software and
open source license.
Android is a freel downloadable open source software stac! for mobile
devices that includes an operating sstem, middleware and !e applications based on
"inu# and $ava.
Google developed Android collaborativel as part of the Open Handset
Alliance, a group of more than %& mobile and technolog companies wor!ing to open
up the mobile handset environment. Android's development !it supports man of the
standard pac!ages used b $ett, and so, due to that fact and $ett's modularit and
lightweight footprint, it was possible to port $ett to it so that it will be able to run on
the Android platform.
This paper on Android deals with the histor of the Android, the earl
prototpes, basic building bloc!s of an android application and the features of the
android.
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CONTENTS
1. INTRODUCTION
2. FEATURES OF ANDROID
3. BUILDING BLOCKS
4. HARDWARE AND SOFTWARE RUNNING ANDROID
5. STORING, RETREIVING AND EXPOSING DATA
6. SECURITY AND PERISSIONS IN ANDROID
!. SYSTE ARCHITECTURE
". APPLICATIONS DEVELOPED ON ANDROID PLATFOR
#. ANDROID VERSIONS
1$. CONCLUSION
11. REFERENCES
INTRODUCTION
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Android is a software platform and operating sstem for mobile devices,
based on the "inu# !ernel, and developed b Google and later the Open Handset
Alliance. (t allows developers to write managed code in the $ava language, controlling
the device via Google-developed $ava libraries. Applications written in ) and other
languages can be compiled to A*+ native code and run, but this development path
isn't officiall supported b Google.
Android is available as open source. Google threw open the entire source
code including networ! and telephon stac!s that were not available previousl,
under an Apache license. )ertain parts that relate to a specific hardware can't be made
open and are not considered part of the Android platform. ith Apache "icense,
vendors are free to add proprietar e#tensions without submitting those bac! to the
open source communit. hile Google's contributions to this platform are e#pected to
remain open-sourced, the branches could e#plode using varieties of licenses.
FEATURES OF ANDROID
H%&'()* +%-*( Android can adapt to traditional smart phone laouts, as well
other /GA, 01, and %1 graphics libraries.
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S*-/%0)Android uses 23"ite to store all its un!-- ( mean, information.
C-&&)** Android supports a wide variet of technologies, including
5luetooth, i6i, G2+71G, and /-1O.
)((%0&0++2 and 2+2 are available for Android, as well as threaded te#t
messaging. 2o ou can send as man te#ties as ou li!e.
W) B/-()/ Android comes pre-loaded with the eb 9it application.
*emember, if ou don't li!e it, ou can alwas switch it out for something else
later on than!s to the open source nature of the Google Android bac!end.
%% V/*%+ %7&)2oftware ou write in $ava can be compiled in 1alvi!
5te codes sa that five times fast. ( !eep ending up with :1anish light bulb:.
These can then be put into a 1alvi! /irtual +achine. 5asicall more robust
applications are supported than on some other +obile Operating 2stems.
)'% S88-/*Android supports a wide range of audio, video, media, and still
formats. +;G-4, OGG, and AA) are ust a few of these.
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B/-%'%(* I&*)&* R)))/
S)/)
C-&*)&* P/-')/
A**
Activities are the most common of the four Android building bloc!s. An activit is
usuall a single screen in our application. ach activit is implemented as a single
class that e#tends the A** %() +%((. our class will displa a user interface
composed of /iews and respond to events. +ost applications consist of multiple
screens. 6or e#ample, a te#t messaging application might have one screen that shows a
list of contacts to send messages to, a second screen to write the message to the chosen
contact, and other screens to review old messages or change settings. ach of these
screens would be implemented as an activit. +oving to another screen is
accomplished b a starting a new activit. (n some cases and activit ma return a
value to the previous activit -- for e#ample an activit that lets the user pic! a photo
would return the chosen photo to the caller.
I&*)&* %&' I&*)&* F+*)/(
Android uses a special class called (ntent to move from screen to screen. (ntent
describes what an application wants done. The two most important parts of the intent
data structure are the action and the data to act upon. Tpical values for action are
+A(? the front door of the application, /(, ;()9, 1(T, etc. The data is
e#pressed as a
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The new activit is informed of the intent, which causes it to be launched. The process
of resolving intents happens at run time when start Activit is called, which offers two
!e benefits@
Activities can reuse functionalit from other components simpl b ma!ing a reBuest
in the form of an (ntent
Activities can be replaced at an time b a new Activit with an eBuivalent (ntent
6ilter
B/-%'%(* R)))/