Gradle script to generate App Links for all app variants in an Android project.

Android AppLinks

/*
 * Created by Harshith Shetty on 11/4/19 12:37 PM.
 * Copyright (c) 2019 People Interactive. All rights reserved.
 *
 */
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'

import groovy.json.JsonBuilder

/**
 * @see <a href="https://developer.android.com/training/app-links">Handling Android App Links</a>
 */

ext.getDate = {
    new Date().format('dd-MMM-yyyy_hh_mm')
}

task createJson {
    group = "App Linking"
    description = "Generate App links Json for Android."
    doLast {
        List<AppLink> allApps=new LinkedList<>()
        android.productFlavors.each { Object product ->
            try {
                if (product.signingConfig != null) {
                    def sha256 = getSha256(product.signingConfig.storeFile, product.signingConfig.storePassword)
                    allApps.add(new AppLink(product.applicationId, sha256))
                }
            }catch(Exception e){
                println("error for ${product.name}")
                println("${e.printStackTrace()}")
            }
        }
        println(allApps.toString())

        createFile("appLinks/",allApps.toString())
    }
}

static def getSha256(keyFile,password)
{
    def command = "keytool -list -v -keystore $keyFile -storepass $password".execute()
    def output = command.inputStream.readLines()
    def SHA256 = output[17].trim().replace("SHA256: ", "")
    return SHA256
}

/**
 * Creates a file in app/build/appLinks folder with the applinks json
 */
def createFile(dir,content){
    def date=getDate()
    File file=new File("$project.buildDir/$dir/")
    file.mkdirs()
    File outputFile=new File("${file.absolutePath}/AppLink_${date}.json")
    outputFile.text= content
    println("Json file available at ${outputFile.absolutePath}")
}



class AppLink{

    List<String> relation

    Target target

    AppLink(packageName,sha256){
        relation= ["delegate_permission/common.handle_all_urls"]
        target=new Target(packageName)
        target.sha256_cert_fingerprints=[sha256]
    }

    def json(){
        def builder=new JsonBuilder()
        builder{
            relation relation
            target(
                    package_name: target.package_name,
                    namespace: target.namespace,
                    sha256_cert_fingerprints: target.sha256_cert_fingerprints
            )
        }
        return builder.toPrettyString()
    }

    @Override
    String toString() {
        return json().toString()
    }
}

class Target{
    List<String> sha256_cert_fingerprints
    String package_name
    String namespace

    Target(packageName){
        this.package_name=packageName
        namespace="android_app"
    }
}