Android/Gradle: Add an asset after the compile phase

Question

I have a task that generates a metadata file based off the compiled classes in an Android Gradle build. I can get it to run by executing it after the compile task:

android.applicationVariants.all { variant ->
    def variantName = variant.name.capitalize()
    def compileSourcesTaskName = "compile${variantName}Sources"
    def compileSourcesTask = project.tasks.findByName(compileSourcesTaskName)
    compileSourcesTask.finalizedBy "myTaskThatGeneratesAssets"
}

Unfortunately, Android has already processed the assets at this point. The new file won't get included in the assembled APK.

An answer to a similar question suggests calling aapt add to add the file to the APK before alignment/signing. This seems like it could work, but the post doesn't go into implementation details. The code to call aapt in the Android Gradle plugin looks fairly complicated for a build script, and I'm not sure how to get access to the IAndroidTarget it references.

I'd appreciate suggestions on how to implement this, or any other solutions!

Answer 1

Okay, here's what I ended up with. It makes two assumptions that may break on later versions of the android gradle plugin (I'm using 1.3.0):

1. The path to the platform tools is ${android.getSdkDirectory().getAbsolutePath()}/build-tools/${android.buildToolsVersion}/
2. The path to the intermediate (resources) APK is ${buildDir}/intermediates/res/resources-${variant.baseName}.ap_

So long as those are true, this should generate a task to add the new asset file using aapt after the resources APK has already been built:

def overlayDir = ... // path to a resources overlay directory that contains "assets/my.json"
def addMyAssetTaskName = "add${variantName}MyAsset"
task "${addMyAssetTaskName}" (type: Exec) {
    dependsOn myTaskThatGeneratesAssets
    workingDir overlayDir
    def aaptCommand = "${android.getSdkDirectory().getAbsolutePath()}/build-tools/${android.buildToolsVersion}/aapt"
    def apkPath = "${buildDir}/intermediates/res/resources-${variant.baseName}.ap_"
    commandLine aaptCommand, 'add', apkPath, "assets/my.json"
}

Then I use finalizedBy like in the question above to addMyAssetTaskName.