Gradle Build Variants for your android project

When developing an app, you usually have many slightly different versions of this app. The most common example is probably the backend you want to use:productionorstaging.

You usually define the base URLs with the other constants of the app. Switching from one environment to the other is done by (un)commenting the right lines:

public static String BASE_URL = "http://staging.tamere.be"//public static String BASE_URL = "http://production.tamere.be"

The process is manual, boring and error prone but hey, changing one line is not that bad, is it?

Then you add more and more features that depends on the environment. You maybe want a different icon and then different input validation rules and then ...

That's where your build tool can help. Let's see how we can automate the process of generating different APKs for different environment with Gradle.

Build variants

Gradle has the concepts of Build Typesand Build Flavors. When combining the two, you get a Build Variant. There two default build types: releaseand debug. We won't change them in our example but we will create two new flavors: productionand staging. As a result, we'll have four different variants:

ProductionDebug
ProductionRelease
StagingDebug
StagingRelease

Sample project

The project is pretty simple but shows how you can define for each build variant:

an app name
an icon
constants (in our case aBASE_URLvariable)

You can download the project on Github. Here are two screenshots of the generated apps. Nothing really fancy:

build.gradle file

buildscript {    repositories {        mavenCentral()    }    dependencies {        classpath 'com.android.tools.build:gradle:0.5.+'    }}apply plugin: 'android'repositories {    mavenCentral()}android {    compileSdkVersion 18    buildToolsVersion "18.0.1"    defaultConfig {        minSdkVersion 15        targetSdkVersion 18    }    productFlavors {        production {            packageName "be.tamere.gradlebuildtypesexample"        }        staging {            packageName "be.tamere.gradlebuildtypesexample.staging"        }    }}dependencies {    compile 'com.android.support:appcompat-v7:18.0.0'}

The definition of the flavors is super simple, all the magic will happen in their folders.

File structure

In thesrcfolder, we've created two directories whose names must match the flavors. We will define all the flavor-specific values. Only specific values are necessary.

The staging version defines new icons while both flavors defines aConstants.java. The app name is defined in thestring.xmlfiles.

├── main│   ├── AndroidManifest.xml│   ├── ic_launcher-web.png│   ├── java│   │   └── be│   │       └── tamere│   │           └── gradlebuildtypesexample│   │               └── MainActivity.java│   └── res│       ├── drawable-hdpi│       │   └── ic_launcher.png│       ├── drawable-mdpi│       │   └── ic_launcher.png│       ├── drawable-xhdpi│       │   └── ic_launcher.png│       ├── drawable-xxhdpi│       │   └── ic_launcher.png│       ├── layout│       │   └── activity_main.xml│       ├── menu│       │   └── main.xml│       ├── values│       │   ├── dimens.xml│       │   ├── strings.xml│       │   └── styles.xml│       ├── values-v11│       │   └── styles.xml│       └── values-v14│           └── styles.xml├── production│   └── java│       └── be│           └── tamere│               └── gradlebuildtypesexample│                   └── Constants.java└── staging    ├── java    │   └── be    │       └── tamere    │           └── gradlebuildtypesexample    │               └── Constants.java    └── res        ├── drawable-hdpi        │   └── ic_launcher.png        ├── drawable-mdpi        │   └── ic_launcher.png        ├── drawable-xhdpi        │   └── ic_launcher.png        ├── drawable-xxhdpi        │   └── ic_launcher.png        └── values            └── string.xml

Android Studio

You can switch between the two flavors in theBuild variantstab of the IDE. Android Studio has some trouble identifying the resources for a non-active flavors.

We are using theproductionflavor, Studio does not understand that thestagingfolder contains source code. Don't worry, it's normal, it will catch up when you switch to the staging variant.

Launch the app with the different flavors to see the result.

The app drawer shows the two icons:

References

http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Product-flavors
Xav's answer on thisStack overflow topicis particularly helpful.

这种方式区分产品与开发环境实在是爽爆了！再也不用去手动改配置文件了！