如何将 AAR 转换为 JAR

情况

我打算使用一个 Java 库，并且我只有一个来自 Maven 存储库的 AAR文件，但是我需要 JAR文件。

背景故事:

我试图编译一个图书馆，但它的 Gradle 结构是不稳定的。所以我要求一个编译过的 jar 文件，它的开发人员从 Maven 存储库中给了我一个 aar 文件(开发人员无法编译他自己的项目)。 Gradle 的配置是一团糟，它依赖于多个图书馆，Gradle 也抛出了一些例外

我试图在我的 IDEA IDE 中使用它，但它看不到它。库项目应该能够被编译成一个 jar 文件，对吗？

问题 :

要将 AAR 文件转换为 JAR 文件，我应该做些什么?

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小开

.aar is a standard zip archive, the same one used in .jar. Just change the extension and, assuming it's not corrupt or anything, it should be fine.

If you needed to, you could extract it to your filesystem and then repackage it as a jar.

1) Rename it to .jar
2) Extract: jar xf filename.jar
3) Repackage: jar cf output.jar input-file(s)
小开
最佳答案

The AAR file consists of a JAR file and some resource files (it is basically a standard zip file with a custom file extension). Here are the steps to convert:

  1. Extract the AAR file using standard zip extract (rename it to *.zip to make it easier)
  2. Find the classes.jar file in the extracted files
  3. Rename it as you like and use that jar file in your project
小开

For those, who want to do it automatically, I have wrote a little two-lines bash script which does next two things:

  1. Looks for all *.aar files and extracts classes.jar from them

  2. Renames extracted classes.jar to be like the aar but with a new extension

    find . -name '*.aar' -exec sh -c 'unzip -d `dirname {}` {} classes.jar' \;
find . -name '*.aar' -exec sh -c 'mv `dirname {}`/classes.jar `echo {} | sed s/aar/jar/g`' \;

That's it!

小开 
 The 'aar' bundle is the binary distribution of an Android Library Project. .aar file
consists a JAR file and some resource files. You can convert it
as .jar file using this steps


1) Copy the .aar file in a separate folder and Rename the .aar file to .zip file using
any winrar or zip Extractor software.


2) Now you will get a .zip file. Right click on the .zip file and select "Extract files".
Will get a folder which contains "classes.jar, resource, manifest, R.java,
proguard(optional), libs(optional), assets(optional)".


3) Rename the classes.jar file as yourjarfilename.jar and use this in your project.

Note: If you want to get only .jar file from your .aar file use the above way. Suppose If you want to include the manifest.xml and resources with your .jar file means you can just right click on your .aar file and save it as .jar file directly instead of saving it as a .zip. To view the .jar file which you have extracted, download JD-GUI(Java Decompiler). Then drag and drop your .jar file into this JD_GUI, you can see the .class file in readable formats like a .java file.

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小开

Android Studio (version: 1.3.2) allows you to seamlessly access the .jar inside a .aar.

Bonus: it automatically decompiles the classes!

Simply follow these steps:

  1. File > New > New Module > Import .JAR/.AAR Package to import you .aar as a module

  2. Add the newly created module as a dependency to your main project (not sure if needed)

  3. Right click on "classes.jar" as shown in the capture below, and click "Show in explorer". Here is your .jar.

access .jar from .aar

小开

Resource based .aar-projects

Finding the classes.jar file inside the .aar file is pretty trivial. However, that approach does not work, if the .aar-project defined some resources (example: R.layout.xyz)

  • Therefore deaar from CommonsGuy helped me to get a valid ADT-friendly project out of an .aar-file. In my case I converted subsampling-scale-image-view. It took me about an hour to set up ruby on my PC.

  • Another approach is using android-maven-plugin for Eclipse/ADT as CommonsGuy writes in his blog.

  • Yet another approach could be, just cloning the whole desired project as source from git and import it as "Existing Android project"

小开

As many other people have pointed out, just extracting the .jar from the .aar file doesn't quite cut it as resources may be missing.

Here are the steps that worked for me (context of Android, your mileage may vary if you have other purposes):

  1. Rename the .aar file to .zip and extract.
  2. The extracted folder is an ADT project that you can import in Eclipse with some minor modifications (see below)!
  3. In the extracted folder rename the contained file classes.jar to whatever you like (in this example myProjectLib.jar) and move it to the lib folder within the extracted folder.
  4. Now in order for Eclipse to accept it you need to put two files into the extracted folder root:
    • .project
    • .classpath
  5. To do that, create a new Android dummy project in Eclipse and copy over the files, or copy over from an existing Android project.
  6. Open the .project file and look for the XML name tag and replace the contents of it with myProjectLib (or whatever you called your jar file above) and save.
  7. Now in Eclipse you can File -> New -> Project -> Android Project from existing source.. and point to the extracted folder content.
  8. After import right click on the newly created project, select Properties -> Android, and check Is Library.
  9. In your main project that you want to use the library for, also go to Properties -> Android and add the newly added myProjectLib to the list of dependencies.
小开

If you are using Gradle for your builds - there is a Gradle plugin which allows you to add aar dependency to your java|kotlin|scala|... modules.

https://github.com/stepango/aar2jar

plugins {
id 'java'
id 'com.stepango.aar2jar' version “0.6” // <- this one
}


dependencies {
compileOnlyAar "com.android.support:support-annotations:28.0.0" // <- Use any AAR dependencies
}

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