[Android system] Android System Architecture Overview, android system architecture

[Android system] Android System Architecture Overview, android system architecture
Overview

The Android system architecture is as follows:

There are four layers from top to bottom:
Application Layer, application framework layer, function library, Android runtime layer, and Linux kernel layer.

The layers are described as follows:

Layered Introduction Application Layer

Contains a series of core Android applications. Most Android applications also belong to this layer, such as calendar, alarm clock, and browser. This layer belongs to the user.

Application Framework Layer

This layer is the layer that common developers need to master. We use various modules in the framework to develop applications. These modules and various services can be reused. By understanding this layer, developers can develop applications faster and better. The following describes each module:

Serial number	Module name	Purpose
1	Activity Manager)	Manage application lifecycle and provide common navigation rollback Functions
2	Window Manager)	The windows mechanism of Android is based on WindowManager. You can add a view to the screen or delete a view from the screen.
3	Content Providers)	Allows applications to access data of another application or share their own data.
4	View System (View Management)	Used to create a view of an application, that is, various UI Components
5	Notification Manager)	Allows applications to display customer notification information in the status bar.
6	Package Manager)	Manage An application package and obtain information about the application.
7	Telephony Manager)	A series of get methods are provided for accessing the status and information related to mobile phone communication. The information includes the status and information of the mobile phone SIM, the status of the Telecom Network, and the information of the mobile phone user.
8	Resource Manager)	Image resources, interface xml resources, fonts, colors, and other resources are centrally managed by the resource manager.
9	Location Manager	Manage map Functions
10	XMPP Services	Scalable messaging and representation protocol service, an XML-based communication protocol

Function library and Android runtime Layer

This layer already involves the underlying layer, which is not involved in general Android applications. This layer includes the function library and Android runtime environment:

Libraries

Serial number	Module name	Function
1	Surface Manager	Management of the display subsystem and seamless integration of 2D and 3D layers for Applications
2	Media Framework (Media Library)	Based on PackeVideo OpenCore, this library supports a variety of common audio and video formats, as well as playback and recording, as well as static image files. The encoding formats include MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG.
3	SQLite	Available to all applications and powerful lightweight Relational Database Engine
4	OpenGL ES	Based on OpenGL ES 1.0 APIs, this library can use hardware 3D acceleration or highly optimized 3D soft acceleration.
5	FreeType	Support for bitmap and vector graph display
6	WebKit	The latest web browser engine is used to support the Andiroid browser or embedded web View.
7	SGL	Underlying 2D graphics engine
8	SSL	Secure Sockets Layer, a security protocol for network communication security and data integrity
9	Libc (system C Library)	A standard C system function library (libc) integrated from BSD, which is specially tailored for Embedded Linux-based devices.

Android Runtime

Serial number	Module name	Function
1	Core Libraries	This core library provides most of the functions of the Java programming language core library.
2	10. Dalvik VM	A virtual machine on the android platform, which is equivalent to the Virtual Machine JVM of Java in the PC

Linux Kernel Layer

This layer is the Linux Kernel on which the Android system depends. The Kernel provides the following functions: