Manually adding aar with dependency pom/iml file

Question

Since I cannot use a private maven in order to share my library, I was thinking in sharing the aar and importing into another project. The problem comes when the aar and jar files does not contain any dependency. So once I manually import the aar in android studio (using Import .JAR/.AA Package) there is no dependency, and I have to manually add all dependencies again. I already generated a pom file through a gradle task, although I cannot find any way to manually import it on the project.

On the build.gradle file automatically generated by the "Import .JAR/.AA Package" is:

configurations.maybeCreate("default")
artifacts.add("default", file('TestSample_1.0.0.aar'))

Is there a way to add the pom/iml file too? something like:

artifacts.add("default", file('pomDependencies.xml'))

Obtund

In my experience you can't do it. Using an aar file you have to add the dependencies manually in your build.gradle. – Monstrance

Thanks for your response @Gabriele Mariotti . Although I have a question, because the gradle knows it when it is compiling from a maven repository, doing something like this: compile "com.lib.testsample:testSample:1.0.0" – Obtund

Using a maven repo gradle searches for the pom file which describes the dependencies. But using a flat dir to import the aar file I don't know a way to add the same pom file. – Monstrance

When you say private maven do you mean a repo like Nexus or Artifactory? You can always publish to a filesystem based repo as well, kind of like your local .m2 directory and then consume your aar from a different build on the same machine, getting all the benefits of transitive dependencies. Is this something that would work for you? – Stuccowork

Hi @RaGe, that is interesting so I can publish to a local filesystem and then somebody else can consume the distributed directory on different machines as well with all the dependencies? – Obtund

Well that's exactly what I'm thinking, but let me try this out to see that it actually works, I don't have an aar producing project handy, will try this later tonight and update. – Stuccowork

Answer 1

1. Publishing

In your aar project, add maven-publish plugin and add necessary plugin configuration.

apply plugin: 'com.android.library'
apply plugin: 'maven-publish'

...

dependencies {
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile 'com.novoda:bintray-release:0.2.7'
}
    
...

publishing {
    publications {
        maven(MavenPublication) {
            groupId 'com.example' //You can either define these here or get them from project conf elsewhere
            artifactId 'example'
            version '0.0.1-SNAPSHOT'
            artifact "$buildDir/outputs/aar/app-release.aar" //aar artifact you want to publish

            //generate pom nodes for dependencies
            pom.withXml {
                def dependenciesNode = asNode().appendNode('dependencies')
                configurations.compile.allDependencies.each { dependency ->
                    def dependencyNode = dependenciesNode.appendNode('dependency')
                    dependencyNode.appendNode('groupId', dependency.group)
                    dependencyNode.appendNode('artifactId', dependency.name)
                    dependencyNode.appendNode('version', dependency.version)
                }
            }
        }
    }
    
    //publish to filesystem repo
    repositories{
        maven {
            url "$buildDir/repo"
        }
    }
}

Few things to note:

1. We're using a custom maven publication, so you have to define what is being published with the artifact clause

2. We have to generate the pom ourselves, in the code above I'm using all compile config dependencies, you may want to make sure all the configs you care about are covered.

Running gradle publish will publish to a maven repo structure to the repo folder, which you can then consume from a different project.

2. Using published .aar

In a different android project, to use the aar published in #1: In top level build.gradle:

allprojects {
    repositories {
        jcenter()
        maven {
            url "D:/full/path/to/repo"
        }
    }
}

add the path to earlier repo as a maven repository. Note that you may have to use the full path, because $buildDir has a different value for this project. In your app build.gradle:

dependencies {
    ...
    other dependencies
    ...
    implementation ('com.example:example:0.0.1-SNAPSHOT@aar'){transitive=true}
}

transitive=true is required for to fetch the transitive dependencies from the pom file.

Stuccowork

Publishing to a local maven and then compiling from that directory totally helps, because I can share the directory whenever I want with all dependencies. Thanks @Stuccowork – Obtund

BTW, It is a tad bit hacky, but it is possible to host a maven repo on git – Stuccowork

Publication should be MavenPublication as the error says, and as my code above shows. – Stuccowork

Great answer. But what if I had imported some .aar file in my library how do I include that? – Unvoice

@Stuccowork i have the pom file included in the artifacts also. But still i keep getting the classNotFoundException. Do you have any insights on this? – Stargell

@Stargell are you able to resolve the issue, because I am also getting the same. – Ritchey

FYI, Use 'configurations.implementation' instead of 'configurations.compile' if you're adding dependencies using 'implementation' :) – Hermetic

Answer 2

Things have changed a little, here's how you do it with the latest versions of gradle

Create the package localy (aar and pom)

Modify your library build.gradle file to include

apply plugin: 'maven-publish'

android {
    ...
    ...
}

dependencies {
    ...
    ...
}

publishing {
    publications {
        maven(MavenPublication) {
            groupId 'com.domain' //You can either define these here or get them from project conf elsewhere
            artifactId 'name'
            version '1.0.0'
            artifact "$buildDir/outputs/aar/sdk-release.aar" //aar artifact you want to publish

            //generate pom nodes for dependencies
            pom.withXml {
            def dependenciesNode = asNode().appendNode('dependencies')
            configurations.implementation.allDependencies.each { dependency ->
                if (dependency.name != 'unspecified') {
                    def dependencyNode = dependenciesNode.appendNode('dependency')
                    dependencyNode.appendNode('groupId', dependency.group)
                    dependencyNode.appendNode('artifactId', dependency.name)
                    dependencyNode.appendNode('version', dependency.version)
                }
            }
        }
    }

    //publish to filesystem repo
    repositories{
        maven {
            url "$buildDir/repo"
        }
    }
}

Run from terminal

./gradlew clean
./gradlew build
./gradlew --console=verbose publishToMavenLocal

The aar and pom files have been created at $HOME/.m2/repository/

How to load the library from a different project

Modify the projects's build.gradle in the following way:

allprojects {
    repositories {
        maven {
            url "/Users/username/.m2/repository/"
        }
        google()
        jcenter()
    }

You can use $rootDir and set a relative path.

Add the library as a dependency in your app module build.gradle

implementation 'com.domain:name:1.0.0'

Custodial

Better and newer approch – Leisha

My maven folder is generated, but it does not have aar file.Any help? – Dispatcher

Wow, I can't believe Gradle makes it this clumsy to generate a POM containing dependencies. – Mandola

@aviran This answer should be checked as the correct one! Thanks a lot, brother! <3 – Benson