Android learning notes (1): basic concepts, android learning notes

Android learning notes (1): basic concepts, android learning notes

This article is referenced in Android development tutorials & Notes

 

Android concept:

Android is a software dedicated to mobile devices. It includes an operating system, middleware, and some important applications. The Beta version of Android SDK provides essential tools and APIs for Android Application Development Using Java on the Android platform.

 

Features

• Application Framework supports Component Reuse and replacement
• Dalvik virtual machines are optimized for mobile devices
• Integrated browsers are based on open-source WebKit Engines
• The optimized graphics library includes a custom 2D graphics library. The 3D graphics library is based on OpenGL ES 1.0 (optional for hardware acceleration)
• SQLite is used for structured data storage
• Multimedia support includes common audio, video, and static image formats (such as MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG,
GIF)
• GSM telephone technology (based on hardware)
• Bluetooth, EDGE, 3G, and WiFi (hardware-dependent)
• Cameras, GPS, compass, and accelerometer (accelerometer) (hardware-dependent)
• A wide range of development environments, including device simulators, debugging tools, memory and performance analysis charts, and integrated development environment plug-ins with Eclipse

 

Application Framework

Developers can also fully access the API framework used by core applications. The architecture design of this application simplifies the reuse of components.
A single application can publish its functional blocks, and any other application can use its released functional blocks (however, follow the box below)
Rack security restrictions ). Similarly, this application reuse mechanism allows you to easily replace program components.
A series of services and systems are hidden behind each application, including:

• Rich and scalable Views can be used to build applications, including lists, grids, and
This box (text boxes), buttons (buttons), and even embedded web browsers.
• Content Providers allow applications to access data (such as the contact database) of another application, or
Users share their own data
• Resource Manager provides access to non-code resources, such as local strings, images, and layout
Files ).
• Notification Manager allows applications to display custom prompts in the status bar.
• Activity Manager is used to manage application lifecycles and provides common navigation rollback functions.

 

Library

Android contains some C/C ++ libraries that can be used by different components in the Android system. They use the Android Application Framework
Provide services for developers. The following are some core databases:
• System C library-a standard C system function library (libc) inherited from BSD, which is specially designed for embedded linux
.
• Media repository-Based on PacketVideo OpenCORE, which supports multiple common audio and video formats for playback and recording.
Static image files. The encoding formats include MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG.
• Surface Manager-manages the display subsystem and provides seamless integration of 2D and 3D layers for multiple applications.
• LibWebCore-a new web browser engine that supports Android browsers and an embedded web View.
• SGL-underlying 2D graphics engine
• 3D libraries-Based on OpenGL ES 1.0 APIs; this library can be implemented using hardware 3D acceleration (if available) or high
Optimized 3D soft acceleration.
• FreeType-bitmap and vector Fonts.
• SQLite-a lightweight relational database engine that is available and powerful for all applications.

 

Android Runtime Library

Android includes a core library that provides most of the functions of the core library of JAVA programming language.
Every Android application runs in its own process and has an independent Dalvik Virtual Machine instance. Dalvik designed
A single device can efficiently run multiple virtual systems at the same time. Dalvik executable file of Dalvik virtual machine execution (. dex ).
Optimized for small memory usage. At the same time, the virtual machine is register-based, and all classes are compiled through the JAVA compiler, and then through the SDK
The "dx" tool in is converted to the. dex format and executed by the virtual machine.
The Dalvik virtual machine depends on some features of the linux kernel, such as the thread mechanism and the underlying memory management mechanism.

 

Android advantages:

Android deficiency:

For details, see Android development tutorials & Notes

Android learning notes

There is no need to worry about this.
I have also studied at qianfeng. Before I officially studied, I was the same as the landlord. I was worried that I would not learn because I had no foundation,
Now, as people come, I think my worries are superfluous.
This is because the students who participate in the study there have no basic knowledge.
Now that I have been working for two years, I feel that the knowledge I have learned is of great help to my current work.
I hope that my suggestions can help the landlord, and I hope that the landlord can find a suitable learning method as soon as possible to complete his learning plan.

Who have android study notes? Can you take a look?

There is no need to worry about this.
I have also studied at qianfeng. Before I officially studied, I was the same as the landlord. I was worried that I would not learn because I had no foundation,
Now, as people come, I think my worries are superfluous.
This is because the students who participate in the study there have no basic knowledge.
Now that I have been working for two years, I feel that the knowledge I have learned is of great help to my current work.
I hope that my suggestions can help the landlord, and I hope that the landlord can find a suitable learning method as soon as possible to complete his learning plan.