Android First Lesson--android architecture

Disclaimer: This article is about learning Android from "Android 4 programming Primer classic" Excerpt! It's just a note to review!

1 Android is a Linux system

Android is a Linux-based open-source mobile operating system. It can be used by any user who intends to make it run on its own device

2 Android Features

There is no fixed hardware and software configuration given the open source of Android and the features that manufacturers can freely customize. However, Android itself supports the following features:

Storage-use SQLite (a lightweight relational database) for data storage.

Connectivity-Supports Gsm/edge, IDEN, CDMA, ev-do, UMTS, Bluetooth (including A2DP and AVRCP), WiFi, LTE, and WiMAX. The 8th chapter will discuss networking in detail.

Messaging-supports SMS and MMS, and is discussed in detail in the 8th chapter.

Web Browser-based on open source WebKit, and integrates with Chrome's V8 JavaScript engine.

Media Support-supports the following media: H.263, H. 3GP or MP4 containers, MPEG-4 SP, AMR, AMR-WB (in 3GP containers), AAC, HE-AAC (in MP4 or 3GP containers), MP3, MIDI, Oggvorbis, WAV, JPEG, PNG, GIF, and BMP.

Hardware Support-accelerometer, camera, digital compass, proximity sensor and Global Positioning System (GPS).

Multi-touch-support multi-touch screen.

Multitasking-Supports multitasking applications.

Flash support-android 2.3 supports Flash 10.1.

tethering-enables Internet Connection Sharing as a wired/wireless hotspot.

3 Android Basic architecture, operating system architecture

The Android operating system can be broadly divided into the following 5 sections on 4 main levels:

Linux kernel-This is the core on which Android is based. This layer includes all the low-level device drivers for a variety of hardware components of an Android device.

Library-Includes all the code that provides the main features of the Android operating system. For example, the SQLite library provides a database that supports applications for data storage. The WebKit library provides many features for browsing the Web.

The Android runtime-which is located on the same level as the library, provides a core set of libraries that enable developers to write Android applications using the Java programming language. The Android runtime also includes the Dalvik virtual machine, which allows each Android application to run in its own process, with an instance of its own Dalvik virtual machine (the Android application is compiled into a Dalvik executable file). Dalvik is a dedicated virtual machine specifically designed for Android and optimized for memory and CPU-limited battery-powered mobile devices.

Application framework-exposes the various features of the Android operating system to application developers, enabling them to use these features in the application.

Apps-on this top level, you can find apps that come with your Android device (such as phones, contacts, browsers, etc.), and apps that you can download and install from the Android Market App Store. Any application you write is at this level.

Android First Lesson--android architecture