Distribute multiple-module library on Bintray for Java and Android developers

Scenario

Before jumping into technical stuffs, I would like to share our story.

Image credit: https://goo.gl/f7K38c

We planned to build a world-class manga(漫画) studio. Our software team firstly created a manga module which serves as a primary library and it is written purely in Java.

After that, we utilize it to produce concrete mangas. Our first masterpiece is Doraemon , and our partners would like to integrate it in their Android apps. So, we developed Android doraemon module which extends manga features.

After hard working hours, our products were ready to be delivered to our partners. Because Java and Android developers use Maven repository, so we decide to release all of mangas on jCenter (one of popular Maven repository hosts). The process is described as the following diagram.


Problem

It has been a while since I published an article about Android library distribution which introduces about Maven repository and necessary steps to distribute your library using Bintray platform. We can follow these steps described in that previous article.

However, our manga studio are growing quickly, and we plan to produce 2 mangas everyday. So,we need to find out how to distribute hundreds or thousands mangas in an easier and more effortless way.

And the last Gradle configuration fits with one module release only.

For awhile, I found that there are a lot of libraries out there in the same situation.

Let’s take Retrofit library as an example, you definitely saw multiple modules involved such as retrofit , retrofit-adapters , retrofit-converters. From library user view, when integrating Retrofit in our apps, we must add its core module via Gradle dependence.

compile ‘com.squareup.retrofit2:retrofit:2.3.0’

Other modules are optional based on our need for specific apps.

// Adapters
com.squareup.retrofit2:adapter-rxjava2
com.squareup.retrofit2:adapter-guava
com.squareup.retrofit2:adapter-java8
// Converters
com.squareup.retrofit2:converter-gson
com.squareup.retrofit2:converter-moshi
….

All modules are put in the same project in development but released in different packages on Maven. You can check them out here core Retrofit, RxJava adapter, Gson converter, and so on.


Finally, we found our own way to achieve this goal. In the following part, I would like to introduce a simple way to distribute multiple-module library on Bintray with detailed explanation and fully source-code sample.

Steps

Please go through following steps if you would like to distribute your library.

  1. Grab Gradle’s files which help you to build and upload libraries on Bintray here. It is similar to Gradle files you saw in my previous article but small changes. Put them inside /jcenter/ folder as in the sample.
  2. We need a common configuration Gradle file I named release-bintray.gradle .
  3. For each module, let’s create its own gradle.properties and declare its specific configuration details.
  4. In module’s build.gradle file, put this line at the bottom to let Gradle know to run it when you call Bintray upload task. 
    apply from: rootProject.file(‘release-bintray.gradle’)
    Sample file.
  5. Almost done, make sure you put your Bintray account credentials inside local.properties file as following (this file is ignored by Git, not be uploaded on version control hosting). 
    bintray.user=your_username
    bintray.apikey=your_api_key (i.e: adfasdf342342j34lba84a25f8c3)
    bintray.gpg.password=your_gpg_password
  6. Let’s run Gradle task with one command. ./gradlew bintrayUpload
  7. Tell other developers to integrate your new awesome library.

For full source codes, please check the sample on Github.

And our two modules are now successfully released into separate packages, manga and doraemon, on Bintray as expected.

Note: The story of building world-class manga studio is just in my imagination, therefore please don’t wait for any more-than-a-stupid-sample masterpiece coming out.


Thank you for reading this post. Find me at Github, Twitter, Facebook, or LinkedIn if you would like to get in touch.