Android application package

APK
Filename extension .apk, .xapk
Internet media type application/vnd.android.package-archive
Type of format Package format
Container for mobile apps
Extended from JAR and ZIP

Android PacKage (APK) is the package file format used by the Android operating system for distribution and installation of mobile apps and middleware.

APK files are analogous to other software packages such as APPX in Microsoft Windows or a Debian package in Debian-based operating systems like Ubuntu. To make an APK file, a program for Android is first compiled, and then all of its parts are packaged into one container file. An APK file contains all of a program's code (such as .dex files), resources, assets, certificates, and manifest file. As is the case with many file formats, APK files can have any name needed, provided that the file name ends in the file extension ".apk".[1][2][3][4]

APK files are a type of archive file, specifically in zip format-type packages, based on the JAR file format, with .apk as the filename extension. The MIME type associated with APK files is application/vnd.android.package-archive.[5]

APK files can be installed on Android-powered devices just like installing software on a PC. When a user downloads and installs an Android application, from either an official source (such as the Google Play Store), or from an unofficial site, they are installing an APK file on to their device. A user or developer can also install an APK file directly to a device (that is, not via download from the network) from a desktop computer, using a communication program such as adb, or from within a file manager app in a process known as sideloading. The installation of APK files downloaded outside the Google Play is disabled by default. Users can install unknown APK files by enabling "Unknown sources" from "Accounts and Security" in Settings.[6]

Package contents

An APK file is an archive that usually contains the following files and directories:

  • META-INF directory:
    • MANIFEST.MF: the Manifest file
    • CERT.RSA: The certificate of the application.
    • CERT.SF: The list of resources and a SHA-1 digest of the corresponding lines in the MANIFEST.MF file; for example:
Signature-Version: 1.0
Created-By: 1.0 (Android)
SHA1-Digest-Manifest: wxqnEAI0UA5nO5QJ8CGMwjkGGWE=
...<ref>
</ref>Name: res/layout/exchange_component_back_bottom.xml
SHA1-Digest: eACjMjESj7Zkf0cBFTZ0nqWrt7w=
Name: res/drawable-hdpi/icon.png
SHA1-Digest: DGEqylP8W0n0iV/ZzBx3MW0WGCA=
  • lib: the directory containing the compiled code that is specific to a software layer of a processor, the directory is split into more directories within it:
    • armeabi: compiled code for all ARM based processors only
    • armeabi-v7a: compiled code for all ARMv7 and above based processors only
    • arm64-v8a: compiled code for all ARMv8 arm64 and above based processors only[7]
    • x86: compiled code for x86 processors only
    • x86_64: compiled code for x86 64 processors only
    • mips: compiled code for MIPS processors only
  • res: the directory containing resources not compiled into resources.arsc (see below).
  • assets: a directory containing applications assets, which can be retrieved by AssetManager.
  • AndroidManifest.xml: An additional Android manifest file, describing the name, version, access rights, referenced library files for the application. This file may be in Android binary XML that can be converted into human-readable plaintext XML with tools such as AXMLPrinter2, apktool, or Androguard.
  • classes.dex: The classes compiled in the dex file format understandable by the Dalvik virtual machine and by the Android Runtime.
  • resources.arsc: a file containing precompiled resources, such as binary XML for example.

See also

References

  1. ↑ "Inside the Android Application Framework" (video). Google Sites. Google. 2008.
  2. ↑ Hatem Ben Yacoub (20 April 2018). "Tips: How to install apk files on Android Emulator". Open Handset Magazine. Archived from the original on 14 October 2008.
  3. ↑ "The Structure of Android Package (APK) Files". OPhone SDN. OPhone Software Developer Network. 17 November 2010. Archived from the original on 8 February 2011.
  4. ↑ chibucks (28 May 2010). "Learn to Fish: General Structure of an APK". SDX-Developers Forum. Simple Machines Forum. Archived from the original on 17 July 2012.
  5. ↑ "Developer description of MIME type for .apk". Androidguys.com. 2008-10-21. Retrieved 2012-08-20.
  6. ↑ "What is an APK File and How to Install it?". Android Picks.
  7. ↑ "ABI Management | Android Developers". developer.android.com. Retrieved 16 June 2018.
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