Go into the Android system

First, Android background

"Android Definition"

Android is the Linux platform-based open-source mobile operating system that Google unveiled on November 5, 2007.

"Development History"

2005, Google acquired Android, launched a text messaging, mobile phone search, positioning and other services.

In 2007, Google announced the launch of the Linux platform-based open-source mobile operating system, officially named Android.

In 2008, Google released the earliest version of Android-Google Android SDK1.0.

In 2009, Google launched a new version of Android 1.5, and began to name the Android version as dessert.

In 2015-2017, Google launched the Android6.0, 7.0, and 8.0 versions in turn.

Second, Android system features and platform architecture

"System Features"

• Application Framework supports reuse and substitution of components (the app is published with the framework's conventions, and other apps can use the module)
• Dalvik virtual machines: optimized for mobile devices
• Integrated Browser: Open source WebKit engine
• SQLite Structured data storage
• Optimized graphics library, multimedia support, GSM phone technology, Bluetooth, etc.
• Build with Software overlay method

"Platform Architecture"

A simple understanding of the architecture:

1. Application (Application layer)

We generally say that the development of the application layer is carried out at this level, of course, including the system built-in a set of applications, using the Java language.

2. Application Framework (Application framework layer)
Regardless of the system built-in or our own written app, we need to use this layer, such as we want to call blacklist, automatically hang up the phone, we need to use the telephone management (Telephonymanager)
With this layer we can easily implement the hang-up operation without needing to be concerned about the underlying implementation.

3. Libraries (library) + Android runtime (Android runtime)
Android gives us a library of C/s + + libraries for different components of the platform, such as the media framework, while the Android runtime is made up of the Android core library + Dalvik virtual machine, and the Dalvik virtual machine is a VM for mobile devices, and it features: It does not require fast CPU computation and a lot of memory space, and each app runs independently of each app in a separate Dalvik virtual machine for a Dalvik process, and his simple running process is as follows:

4. Linux kernel

Here are the things that involve the underlying drivers, some system services such as security, memory management, and process management.

III. Building the development environment

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Go into the Android system