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This article mainly explains "what is the use of SDK in Android". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the use of SDK in Android"?

What is Android SDK?

SDK (Software Development Kit) Software Development Kit is a collection of development tools used by software development engineers to build application software for specific software packages, software frameworks, hardware platforms, operating systems, etc. So Android NSDK is the exclusive software development kit for Android.

Android SDK directory structure

After decompressing, you can install it, including the directory structure as shown below:

1. Add-ons

This directory holds Android's extended libraries, such as Google Maps, but if you do not choose to install Google API, the directory is empty.

2. Docs

This directory is the development document of developer.Android.com, including the introduction of SDK platform, tools, ADT, development guide, API documentation, related resources and so on.

3. Extras

This directory is used to store Android additional support files, which mainly contains Android's support support package, several Google tools and drivers, and Intel's IntelHaxm.

4. Platforms

This directory is used to store files related to the Android SDK Platforms platform, including fonts, res resources, templates, etc.

5. Platform-tools

This directory contains various platform tools, which mainly contains the following sections.

The name functions as the api directory api-versions.xml file, which is used to indicate that there are only dx.jar files in the lib directory of the required classes, methods, interfaces, etc. When starting dx.bat for the platform tool, load and use the class aapt.exe in the jar package to package the developed application into an APK installation file. If you develop with Eclipse There is no need to enter commands + parameters through the command window to achieve packaging adb.exe (Android Debug Bridge debug bridge) through which the Android mobile phone (or simulator) is connected with the PC side, and the operation of the mobile phone can be controlled on the PC side. If you develop with Eclipse, normally ADB will start automatically, and then we can debug the Android program through DDMS. Aidl.exe (Android Interface Definition Language) Android internal process communication interface description language, used to generate code that can be used for inter-process communication (Inter-Process Communication,IPC) in Android devices dexdump.exe can decompile .dex files, for example, .dex files contain three classes, and there will be three .class files after decompilation, through which you can roughly understand the original Java code. Dx.bat converts .class bytecode file to Android bytecode. Dex file fastboot.exe can restart the system, rewrite the kernel, view connected devices, write partitions, clear partitions and other operations Android llvm-rs-cc.exeRenderscript uses LLVM low-level virtual machines, the main function of llvm-rs-cc.exe is to deal with Renderscript NOTICE.txt and source.propertiesNOTICE.txt just give some hints Source.properties is a resource attribute information file, which mainly displays the resource generation time, system type, resource URL address, and so on. 6. Samples

Samples is the default example project that comes with Android SDK, and the apidemos in it is highly recommended for beginners.

7. System-images

This directory stores all the pictures used by the system.

8. Temp

This directory stores temporary files in the system.

9. Tools

As the tools folder under the root directory of SDK, it contains important tools, such as ddms to start Android debugging tools such as logcat, screenshot and file manager; draw9patch is a tool for drawing scalable PNG images on Android platform; sqlite3 can operate SQLite database on PC; monkeyrunner is a good stress test application to simulate user random buttons; mksdcard is a tool for creating SD image of simulator Emulator is the main program of the Android simulator, but starting with Android 1.5, you need to enter the appropriate parameters to start the simulator; traceview is an important debugging tool on the Android platform.

Android.jar

As a Java project, the utility class to be used, the JAR package, is usually introduced.

In Android development, the vast majority of development toolkits are packaged in a file called Android.jar. When you expand it in Eclipse, you can see the packages in J2SE, the packages in the Apache project, and the package files of Android itself. The package file of Android mainly includes the following:

The name function Android.app provides a high-level program model and basic running environment Android.content contains a variety of classes for accessing and publishing data on devices Android.database provides classes for managing a variety of audio and video media interfaces Android.net provides classes for network access through content providers browsing and manipulating the underlying graphics library Android.location of the database Android.graphics and related services Android.media Beyond the usual java.net.* interface Android.os provides system services, message transmission, IPC mechanism Android.openg provides OpenGL tools Android.provider provide classes, content providers that access Android Android.telephony provide API interactions related to phone calls Android.view provides a basic user interface framework Android.util involves instrumental methods For example, the operation of time and date Android.webkit default browser operation interface Android.widget contains various UI elements (most of which are visible) use the Android API expansion pack in the screen of the application

The core Android API can be used on every phone, but there are still some API interfaces that have their own special scope of application, which is the so-called "optional API". These API are "optional" mainly because a handheld device does not have to fully support this type of API, or even not at all.

1. Location-Based Services (location based service)

The Android operating system supports GPS API-LBS, which can receive satellite signals by integrating GPS chips, and obtain the coordinate data of the current mobile phone through at least three satellites and atomic clocks in the GPS global positioning system. Through conversion, it can become a specific location on the map. This error can be reduced to 10 meters on the mobile phone. The famous SiRF star can be seen in the Google Mobile Development Alliance. Therefore, the price of gPhone phones integrated with GPS will not be very expensive in the future.

At the same time, Google is developing a base station-based positioning technology, MyLocation, which can locate faster, and the base station location is faster than the GPS location that takes about 1 minute.

2. Media APIs (Multimedia Interface)

Many audio and video decoders and related multimedia API are integrated on the Android platform. Through these optional API, manufacturers can make mobile phones support MP3, MP4, high-definition video playback processing and so on.

3. 3D Graphics with OpenGL (3D graphics processing OpenGL)

Optional API. Game and entertainment functions on the Android platform, such as supporting 3D games or application scenes, require 3D technology. Mobile phone manufacturers integrate different levels of 3D accelerated graphics chips according to the phone's screen and location to enhance the entertainment of gPhone phones. According to news from Qualcomm, the latest display chip will easily surpass Sony PS3 on gPhone.

4) Low-Level Hardware Access (low-level hardware access)

This function is mainly used to control the operation of the underlying aspects of the mobile phone, the design of the underlying hardware operation will be mainly customized by various mobile phone hardware manufacturers to support the operation and management of different devices, such as Bluetooth (Bluetooth) and WIFI wireless network support.

Thank you for your reading, the above is the content of "what is the use of SDK in Android". After the study of this article, I believe you have a deeper understanding of what the use of SDK in Android has, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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