Introduction to Android (Jeudis du libre)

transcript

Introduction to AndroidChristophe Beyls

Jeudis du Libre - April 2012

About the speaker

● Developer living in Brussels.● Uses various programming languages,

mostly Java and C#.● Likes coding, hacking devices, travelling,

movies, music, (LOL)cats.

● Worked for:

Agenda

1. Introduction - Why Android?2. History3. System architecture and its free parts4. The SDK5. The building blocks of an Android

app6. Devices hacking and custom ROMs7. Questions & Answers.

Why Android?

■ Open architecture.■ Apps may be distributed outside the Google

Play Store (Android Market) and installed on any device.

History

■ 2003: Android Inc.founded by Andy Rubin.

■ 2005: Purchase by Google. ■ January 2007: Apple announces

the iPhone.■ June 2007: iPhone released.

History

November 2007Google creates the Open Handset Alliance consortium with 34 founding members. Manufacturers: HTC, LG, Sony, Motorola, Samsung.Semiconductors: Qualcomm, Intel, nVidia, ...Operators: T-Mobile, Sprint, Telefónica...Software: eBay, Google, Nuance, ...

History

November 2007: First beta SDK released.

History

December 2007: Early prototype unveiled.

History

February 2008: Apple releases the iPhone SDK.June 2008: Apple opens the App Store and releases the iPhone 3G.

History

September 2008Android 1.0 on HTC Dream (T-Mobile G1).

History

February 2009: Android 1.1 (bugfixes).April 2009: Android 1.5 Cupcake (Widgets, virtual keyboard).June 2009: 2 more Android phones released. September 2009: Android 1.6 Donut(Text-to-speech, multiple screen resolutions).

HTC Magic HTC Hero

History

November 2009: Android 2.0 Eclair(HTML5, Contacts + Bluetooth APIs).January 2010: Nexus One released(first Google-branded phone).Android 2.1 (bugfixes, live wallpapers). April 2010: Apple iPad released.May 2010: Android 2.2 FroYo(speed, JIT compiler, push notifications, Adobe Flash support, WiFi hotspot).

History

2Q10: Android outsells iOS devices worldwide.

History

December 2010: Android 2.3 Gingerbreadon Google Nexus S.(Black interface, NFC, native SIP,WebM support)

History

February 2011: Android 3.0 Honeycombon the first Android tablet: the Motorola Xoom.■ New UI: Holo theme, Fragments, Action Bar■ Full 2D hardware acceleration.

History

3Q11: Android market share doubles compared to 3Q10 and becomes to most used mobile OS.

History

November 2011:Android 4.0 Ice Cream Sandwichon Google/Samsung Galaxy Nexus.

■ Unified OS for Smartphonesand Tablets.

■ Faster, smoother■ Improved browser■ Roboto font■ Face unlock.

System Architecture

System architecture - Bionic libc

■ Fast, optimized for ARM■ Lightweight (200 ko), half the size of glibc■ No C++ Exceptions■ No Standard Template Library■ New pthreads implementation

[does not support pthread_cancel()]■ Can be exploited directly through NDK

(native development kit) BSD licencehttps://github.com/android/platform_bionic

System architecture - WebKit

■ Developed by KDE, Apple, Nokia, Google and others.

■ Android 2.2+ uses faster V8 javascript engine instead of JavascriptCore.

■ No differences between Android browser and webviews embedded in apps.

System architecture -Media Framework

Based on OpenCORE and Stagefright (2.2+).

System architecture -Media Framework - Base support

■ Audio codecs: AAC, MP3, AMR, PCM, MIDI, Ogg Vorbis, FLAC (3.1+)

■ Image codecs: JPEG, GIF, BMP, PNG, WebP (4.0+)

■ Video codecs: H.263, H.264, MPEG-4 SP, VP8 (2.3.3+)

■ Containers: 3GPP, MPEG-4,Matroska (.mkv) (4.0+)

■ Manufacturers may add more codecs.

Italic = patent-free

System architecture - Runtime

■ Android uses only the Java language,not the Java platform.

■ Dalvik Virtual Machine developed by Google.

■ Uses minimal memory.■ Java bytecode is converted to smaller

Dalvik bytecode at build time (.dex files).■ Uses Just-In-Time compilation since

Android 2.2 for better performance.■ Standard library is based on Apache

Harmony open source implementation.

Android Open Source Project (AOSP)

source.android.com

Android Open Source Project (AOSP)

Almost... fully open:■ Google publishes source code when they

decide it.■ No real interaction with Google teams.■ Not everything is open source:

○ Proprietary binary drivers○ Google Apps: Google Maps, Gmail, Google

Contacts/Calendar/Bookmarks Sync, Google Talk, Play Store (Android Market), Youtube, Weather widget, Text-To-Speech, Voice Search.

The SDK

iPhone / iPad■ Hardware: Mac (with latest Mac OS X)■ IDE: XCode (free)■ Language: Objective-C. Windows Phone 7 / Windows 8■ Hardware: PC with Microsoft Windows■ IDE: Microsoft Visual Studio (free)■ Language: C#, Visual Basic.

The SDK

Android■ Hardware: Any x86■ IDE: Eclipse, Netbeans, IntelliJ IDEA■ Language: Java.

Installing the SDK

developer.android.com/sdk

Official SDK Tools

■ ADB (Android Debug Bridge)■ ARM Emulator (based on QEMU)■ DDMS (Dalvik Debug Monitor Server)■ Proguard (Java optimizer & obfuscator)■ ADT Plugin for Eclipse:

○ Project wizards○ Java editor with code completion, refactoring, ...○ Lint integration○ Visual layout editor

+ NDK (Native Development Kit)

Official SDK Tools - ADT Plugin

Resources■ By language■ By screen density■ By screen orientation■ By Android version

Official SDK Tools - ADT Plugin

User Interface

developer.android.com/design

Android apps: the building blocks

Activities: screens with a life cycle.

Fragments: portions of screens with a life cycle.

■ Background services.

■ Intents: IPC mechanism betweenActivities and/or Services.Action + Data○ Action: View, Edit, Dial, ..., custom actions○ Data: URL scheme or any MIME type.

■ Everything in the system use intents

and is interchangeable.

Special apps:■ Live wallpapers■ Widgets

Diversity

Development challenges: ■ Write fast high-level code or use NDK

■ Support multiple devices types○ Phones○ Tablets○ Google TVs

■ Support multiple Android versions.

Diversity - Android versions

Use features of newer Android versionswhile staying compatible with older runtimes:Isolate special functionality in separate classes. MyInterface implementation;

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO)

implementation = new FroYoImplementation();else

implementation = new CompatibleImplementation();

The upgrade problem

Manufacturers provide custom user interfaces.

HTC SenseSony Ericsson

Timescape Samsung TouchWiz

The upgrade problem

■ Updating the custom user interface to a new Android version requires a lot of work.

■ Manufacturers focus on selling you their latest hardware, not providing support for older hardware.

■ On Android, upgrades usually depend on carriers. (The Proximus case)

■ Many manufacturers don't do OTA updates.■ Average official support time:

○ 3 years for Apple○ <= 2 years for most Android phones.

The upgrade solution:Installing community ROMs

Why hack ?■ Give choice to the user.■ Remove bloatware.■ Provide longer term support and upgrades. Custom ROMs:Complete firmware (OS, UI, base applications) created by the community.

Hacking - Custom ROMs

Different kinds of custom ROMs:■ Modified original vendor versions■ Ported from another device (experimental)■ Build from source (AOSP) Hack challenges■ Locked hardware (HTC S-ON).■ Binary drivers:

Radio (Wifi - Bluetooth - GPS), Graphics, NFC, sometimes accelerometers.

Hacking

Warning: voids warranty.

Successfully hacked:

HTC G1, HTC Magic, HTC Hero, HTC Desire, HTC Legend, Dell Streak, Samsung Galaxy S, Samsung Galaxy Gio, Samsung Galaxy Tab, Acer Liquid, ZTE Blade, Motorola Xoom,Sony Ericsson Xperia X10.

Hacking - The Bible

forum.xda-developers.com

Cyanogenmod - www.cyanogenmod.com

MIUI - miuiandroid.com

BootloaderIPL SPL Kernel

RecoveryRadio

System

Hacking basics

■ ROM

■ Recovery Boot modes:■ Normal OS■ Recovery■ SPL (Flash mode)

Hacking basics

Custom ROM:Zip file containing■ system files■ kernel■ optionnally radio. Can be installed easilyusing a custom recovery.

Hacking basics - 1. Flash tools

FastBoot (Google, HTC, Sony Ericsson) ■ Android standard command line Flash Tool■ Available in the SDK (Win, Mac, Linux)■ Useful commands: fastboot oem unlockfastboot flash recovery recovery.imgfastboot boot recovery.imgfastboot erase data -w

Hacking basics - 1. Flash tools

Samsung ODIN (Windows)

Hacking basics - 2. Root access

■ Root access allows to perform restricted operations like:○ writing files on system partition○ flashing a custom recovery directly from Android

OS. ■ It requires:

○ Patching or replacing the kernel○ - or -○ Use phone-specific kernel exploits

(mainly through ADB).

Hacking basics - 2. Root access

Recap: How to change your ROM

1. Go to a forum / wiki and learn the procedure2. Use:

a. fastbootb. the vendor flash toolc. a root hackto install a custom recovery on your phone.

3. Download a custom ROM as zip file and place it to your SD card/internal storage.

4. Reboot your phone in custom recovery and install the ROM. Reboot. Done.

Hacking basics - Custom recovery

ClockworkModrecovery

Hacking basics - Custom recovery

Thank you for watching.

Questions? Twitter: @BladeCoderWeb: digitalia.be

Introduction to Android (Jeudis du libre)

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