Over the course of a few days this week, for my side project, I implemented Android in-app billing v2 in Kotlin. It took about 5 hours to read through everything and implement it, but it should have taken less than an hour with the right sample code and walk-through.
This is that walk-through that I would have wanted to just quickly implement subscription services in my app.
Google, in general, has good documentation for their in-app billing, but their code sample was more helpful for me, even though it wasn't updated for the latest version of the library. There was a major version update with breaking changes that couldn't be copy-pasted into a current app.
There are about ten main pages of documentation for in-app billing, but to simply get started and running, you will only need one doc page and one sample code page:
- https://developer.android.com/google/play/billing/billing_overview
- https://github.com/googlesamples/android-play-billing/blob/master/TrivialDrive_v2/shared-module/src/main/java/com/example/billingmodule/billing/BillingManager.java
Or...
I can just provide the highlights and updated code that will actually work...
- Product IDs must be unique and can NOT be reused. Product IDs must start with a lowercase letter or a number and must be composed of only lowercase letters (a-z), numbers (0-9), underscores (_), and periods (.). The product ID 'android.test' is unavailable for use, along with all product IDs that start with 'android.test'.
- Subscriptions can NOT be unpublished
- Subscription prices must be within a certain price range, US currently USD .99 - 400.00: https://support.google.com/googleplay/android-developer/table/3541286
- The easiest way to test your purchase flow is to have testers defined in the Google Play Console > Settings > Developer account > Account details > License Testing > 'Gmail accounts with testing access'
Code:
- Add
implementation 'com.android.billingclient:billing:2.0.0'in your app's build.gradle file - Add
<uses-permission android:name="com.android.vending.BILLING" />in your app's AndroidManifest.xml file - Copy+paste this gist, then change the SKUs for your usage: https://gist.github.com/danialgoodwin/5bc709b19b776e707a827772401aaf96 (shown below)
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| package dev.goodwin | |
| import android.app.Activity | |
| import android.util.Log | |
| import com.android.billingclient.api.* | |
| import com.android.billingclient.api.BillingClient.BillingResponseCode | |
| import com.android.billingclient.api.BillingClient.FeatureType | |
| import dev.goodwin.BillingManager.Companion.formatPeriod | |
| /** | |
| * When using this class: | |
| * - Call `queryPurchases()` in your Activity's onResume() method | |
| * - Call `query*SubscriptionSkuDetails()` when you want to show your in-app products | |
| * - Call `startPurchaseFlow()` when one of your in-app products is clicked on | |
| * - Call `destroy()` in your Activity's onDestroy() method | |
| * | |
| * Good example: https://github.com/googlesamples/android-play-billing/blob/master/TrivialDrive_v2/shared-module/src/main/java/com/example/billingmodule/billing/BillingManager.java | |
| * | |
| * Note: More security can be added by using 'developer payloads', but that is not used here. | |
| */ | |
| class BillingManager( | |
| private val activity: Activity, | |
| private val onEntitledPurchases: (List<Purchase>) -> Unit, | |
| private val onPurchase: (Purchase) -> Unit | |
| ) { | |
| private val purchasesUpdatedListener = PurchasesUpdatedListener { billingResult, purchases -> | |
| when (billingResult.responseCode) { | |
| BillingResponseCode.OK -> { | |
| purchases?.let { | |
| for (purchase in purchases) { | |
| when (purchase.purchaseState) { | |
| Purchase.PurchaseState.PURCHASED -> { | |
| onPurchase(purchase) | |
| if (!purchase.isAcknowledged) { | |
| val acknowledgePurchaseParams = AcknowledgePurchaseParams.newBuilder() | |
| .setPurchaseToken(purchase.purchaseToken) | |
| .build() | |
| billingClient.acknowledgePurchase(acknowledgePurchaseParams) { billingResult -> | |
| log("acknowledgePurchase(), billingResult=$billingResult") | |
| } | |
| } | |
| } | |
| Purchase.PurchaseState.PENDING -> { | |
| // Here you can confirm to the user that they've started the pending | |
| // purchase, and to complete it, they should follow instructions that | |
| // are given to them. You can also choose to remind the user in the | |
| // future to complete the purchase if you detect that it is still | |
| // pending. | |
| } | |
| } | |
| } | |
| } | |
| log("onPurchasesUpdated(), $purchases") | |
| } | |
| BillingResponseCode.USER_CANCELED -> log("onPurchasesUpdated() - user cancelled the purchase flow - skipping") | |
| else -> log("onPurchasesUpdated() got unknown resultCode: ${billingResult.responseCode}") | |
| } | |
| } | |
| private val billingClient: BillingClient = BillingClient.newBuilder(activity) | |
| .enablePendingPurchases() | |
| .setListener(purchasesUpdatedListener) | |
| .build() | |
| private var isBillingServiceConnected = false | |
| init { | |
| startServiceConnection { | |
| queryPurchases() | |
| } | |
| } | |
| fun queryPurchases() { | |
| if (isSubscriptionPurchaseSupported()) { | |
| val purchasesResult = billingClient.queryPurchases(BillingClient.SkuType.SUBS) | |
| if (purchasesResult.responseCode == BillingResponseCode.OK) { | |
| onEntitledPurchases(purchasesResult.purchasesList) | |
| } else { | |
| log("Error trying to query purchases: $purchasesResult") | |
| } | |
| } else { | |
| onEntitledPurchases(emptyList()) | |
| } | |
| } | |
| fun queryBusinessSubscriptionSkuDetails(onSuccess: (List<SkuDetails>) -> Unit, onError: (code: Int, message: String) -> Unit) { | |
| startServiceConnection { | |
| querySubscriptionSkuDetails(listOf(Sku.BUSINESS_MONTHLY, Sku.BUSINESS_YEARLY), onSuccess, onError) | |
| } | |
| } | |
| fun queryIndividualSubscriptionSkuDetails(onSuccess: (List<SkuDetails>) -> Unit, onError: (code: Int, message: String) -> Unit) { | |
| startServiceConnection { | |
| querySubscriptionSkuDetails(listOf(Sku.INDIVIDUAL_YEARLY), onSuccess, onError) | |
| } | |
| } | |
| fun startPurchaseFlow(sku: SkuDetails) { | |
| startServiceConnection { | |
| val flowParams = BillingFlowParams.newBuilder().setSkuDetails(sku).build() | |
| val billingResult = billingClient.launchBillingFlow(activity, flowParams) | |
| log("startPurchaseFlow(...), billingResult=$billingResult") | |
| } | |
| } | |
| fun destroy() { | |
| log("destroy()") | |
| if (billingClient.isReady) { | |
| billingClient.endConnection() | |
| } | |
| } | |
| private fun startServiceConnection(task: () -> Unit) { | |
| if (isBillingServiceConnected) { | |
| task() | |
| } else { | |
| billingClient.startConnection(object : BillingClientStateListener { | |
| override fun onBillingSetupFinished(billingResult: BillingResult) { | |
| log("onBillingSetupFinished(...), billingResult=$billingResult") | |
| if (billingResult.responseCode == BillingResponseCode.OK) { | |
| isBillingServiceConnected = true | |
| task() | |
| } | |
| } | |
| override fun onBillingServiceDisconnected() { | |
| log("onBillingServiceDisconnected()") | |
| isBillingServiceConnected = false | |
| // Try to restart the connection on the next request to | |
| // Google Play by calling the startConnection() method. | |
| } | |
| }) | |
| } | |
| } | |
| private fun querySubscriptionSkuDetails(skus: List<String>, onSuccess: (List<SkuDetails>) -> Unit, onError: (code: Int, message: String) -> Unit) { | |
| val params = SkuDetailsParams.newBuilder().setSkusList(skus).setType(BillingClient.SkuType.SUBS) | |
| billingClient.querySkuDetailsAsync(params.build()) { billingResult, skuDetailsList -> | |
| if (billingResult.responseCode == BillingResponseCode.OK && skuDetailsList != null) { | |
| onSuccess(skuDetailsList) | |
| } else { | |
| onError(billingResult.responseCode, billingResult.debugMessage) | |
| } | |
| } | |
| } | |
| private fun isSubscriptionPurchaseSupported(): Boolean { | |
| val response = billingClient.isFeatureSupported(FeatureType.SUBSCRIPTIONS) | |
| if (response.responseCode != BillingResponseCode.OK) { | |
| log("isSubscriptionPurchaseSupported(), not supported, error response: $response") | |
| } | |
| return response.responseCode == BillingResponseCode.OK | |
| } | |
| private fun log(message: String) { | |
| Log.d("BillingManager", message) | |
| } | |
| companion object { | |
| /** | |
| * P1W equates to one week, | |
| * P1M equates to one month, | |
| * P3M equates to three months, | |
| * P6M equates to six months, | |
| * P1Y equates to one year | |
| */ | |
| fun formatPeriod(period: String, isIncludeSingularNumber: Boolean): String { | |
| if (period.count() < 3) return "" | |
| val isSingular = period[1] == '1' | |
| val unit = when (period[2]) { | |
| 'W' -> if (isSingular) "week" else "weeks" | |
| 'M' -> if (isSingular) "month" else "months" | |
| 'Y' -> if (isSingular) "year" else "years" | |
| else -> "" | |
| } | |
| return if (isSingular && !isIncludeSingularNumber) unit else "${period[1]} $unit" | |
| } | |
| } | |
| /** The format of SKUs must start with number or lowercase letter and can contain only numbers (0-9), | |
| * lowercase letters (a-z), underscores (_) & periods (.).*/ | |
| object Sku { | |
| const val BUSINESS_MONTHLY = "business_monthly2" // Made a mistake with "business_monthly", accidentally make it yearly, so we can't use that SKU anymore | |
| const val BUSINESS_YEARLY = "business_yearly" | |
| const val INDIVIDUAL_YEARLY = "individual_yearly" | |
| // Testing | |
| // const val TEST_PURCHASED = "android.test.purchased" | |
| // const val TEST_CANCELED = "android.test.canceled" | |
| // const val TEST_UNAVAILABLE = "android.test.item_unavailable" | |
| } | |
| } | |
| fun SkuDetails.displayPeriod() = formatPeriod(this.subscriptionPeriod, isIncludeSingularNumber = false) | |
| fun SkuDetails.displayIntroductoryPeriod() = formatPeriod(this.introductoryPricePeriod, isIncludeSingularNumber = true) |
From "0" to "it works on my machine" :p
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