How to implement In-App Billing in an Android application?

Question

It seems that it is quite complicated to implement In-App Billing in an Android app. How could I do this? The sample app from the SDK only has one Activity, which kind of ov

Answer 1

Okay this is one of those things that doesn't have very much documentation available online, so I'm going to do my best to explain everything step by step. Taken from my blog post, which is a more detailed version of this (with screenshots), here on The Millibit. Without further ado,

Step One: Permissions This is the easiest step. Navigate to your manifest.xml file and add the following line under your tag:

This will give your app the permissions to access In-App Billing. If you are targetting versions above API 22, you will need to make sure that this permission is granted at runtime.

Step Two: Play Console Now you need to upload your app to the Google Play Console. We are not publishing our app to the public yet (don’t worry), we are just uploading it to the BETA RELEASE section, which will allow us to test In-App Purchases. The reason we need to do this is that Google needs to have some version of your APK uploaded for the billing processes to actually work.

1. Go to https://play.google.com/apps/publish/

2. Create the Application

3. Follow the steps to set up your app

4. Go to App Releases

5. Navigate to Beta

6. Create an APK of your app in Android studio and upload it to the Beta production in the Play Console

(before releasing make sure that you have already filled out the Store Listing ,Content Rating and Pricing and Distribution)

7. Hit the magic button (publish!)

Step Three: Setup Project Okay this is the part where you have to copy and paste a bunch of files.

First, grab this file, download it, and place it under src/mainIt should build itself into a folder Next, grab this entire util folder and paste it into src/java folder. Then rebuild your project to resolve errors. The Util Folder Contains The Following Classes:

• IabBroadcastReceiver
• IabException
• IabHelper
• IabResult
• Inventory
• Purchase
• Security
• SkuDetails

Step Four: Create Products

1. Create Managed Product

2. Click save and make a “pricing template”

Here, you will select the price of this product. You can choose the price for different countries, or have it automatically adjust if you just select all countries under your price:

3. Make sure the in-app product is activated and linked with the correct application in the console one last time.

Finally, note the ID of your product. We will use this ID in the next few steps.

4. Get your Base64EncodedString

Head over to “Services & APIs” and grab your Base64EncodedString. Copy and paste this to a notepad somewhere so that you have access to it. Do not share this with anyone, they will be able to do malicious things with it.

Step Five: Finally! We can start coding: We will first bind to the in-app billing library, and query for what the user has/hasn’t bought. Then, we will buy the product that we set up earlier.

First, import everything we set up earlier:

import util.*;

Now we will use an IabHelper object called mHelper, and we will do everything with this.

base64EncodedPublicKey = ""; //PUT YOUR BASE64KEY HERE

mHelper = new IabHelper(this, base64EncodedPublicKey);
mHelper.enableDebugLogging(false); //set to false in real app


mHelper.startSetup(new IabHelper.OnIabSetupFinishedListener() {
    public void onIabSetupFinished(IabResult result) {
        if (!result.isSuccess()) {
            // Oh no, there was a problem.

            if (result.getResponse() == 3) {
                new AlertDialog.Builder(MainActivity.this)
                        .setTitle("In app billing")
                        .setMessage("This device is not compatible with In App Billing, so" +
                                " you may not be able to buy the premium version on your phone. ")
                        .setPositiveButton("Okay", null)
                        .show();
            }

            Log.v(TAG, "Problem setting up In-app Billing: " + result);
        } else {
            Log.v(TAG, "YAY, in app billing set up! " + result);
            try {
                mHelper.queryInventoryAsync(mGotInventoryListener); //Getting inventory of purchases and assigning listener
            } catch (IabHelper.IabAsyncInProgressException e) {
                e.printStackTrace();
            }
        }
    }
});

Okay, let me break down what’s going on here. Basically, we are calling “startSetup” to initialize our “IabHelper”. If the setup is successful, we query what purchases the user already has and store the responses in mGotInventoryListener, which we will code next:

IabHelper.QueryInventoryFinishedListener mGotInventoryListener
        = new IabHelper.QueryInventoryFinishedListener() {
    public void onQueryInventoryFinished(IabResult result,
                                         Inventory inventory) {

        i = inventory;

        if (result.isFailure()) {
            // handle error here

            Log.v(TAG, "failure in checking if user has purchases");
        } else {
            // does the user have the premium upgrade?
            if (inventory.hasPurchase("premium_version")) {

                premiumEditor.putBoolean("hasPremium", true);
                premiumEditor.commit(); 

                Log.v(TAG, "Has purchase, saving in storage");

            } else {

                premiumEditor.putBoolean("hasPremium", false);
                premiumEditor.commit();

                Log.v(TAG, "Doesn't have purchase, saving in storage");

            }
        }
    }
};

The above code is pretty self-explanatory. Basically, it just checks what purchases the user already has. Now that we know whether or not the user has already purchased our product, we know whether or not to ask them to purchase our item! If they’ve never bought our product before, let’s start a purchase request:

public void buyPremium() {
    try {

     mHelper.flagEndAsync();//If any async is going, make sure we have it stop eventually
     mHelper.launchPurchaseFlow(this, "premium_version", 9, mPurchaseFinishedListener, "SECURITYSTRING"); //Making purchase request and attaching listener
    } catch (Exception e) {
        e.printStackTrace();

mHelper.flagEndAsync();//If any async is going, make sure we have it stop eventually




        new AlertDialog.Builder(MainActivity.this)
                .setTitle("Error")
                .setMessage("An error occurred in buying the premium version. Please try again.")
                .setPositiveButton("Okay", null)
                .show();
    }
}


    @Override

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

    Log.d(TAG, "onActivityResult(" + requestCode + "," + resultCode + "," + data);

    // Pass on the activity result to the helper for handling

    if (!mHelper.handleActivityResult(requestCode, resultCode, data)) {

    }

    else 
        Log.d(TAG, "onActivityResult handled by IABUtil.");
    }

}

IabHelper.OnIabPurchaseFinishedListener mPurchaseFinishedListener
        = new IabHelper.OnIabPurchaseFinishedListener() {
    public void onIabPurchaseFinished(IabResult result, Purchase purchase) {

        Log.v(TAG, "purchase finished");

        if (purchase != null) {

            if (purchase.getSku().equals("premium_version")) {

                Toast.makeText(MainActivity.this, "Purchase successful!", Toast.LENGTH_SHORT).show();

                premiumEditor.putBoolean("hasPremium", true);
                premiumEditor.commit();
            }
        } else {
            return;
        }
        if (result.isFailure()) {
            return;
        }
    }
};

Here we purchase the item (with the ID we generated in the play console earlier) with the following:

 mHelper.launchPurchaseFlow(this, "premium_version", 9, mPurchaseFinishedListener, "SECURITYSTRING"); //Making purchase request and attaching listener

Notice that we passed mPurchaseFinishedListener into the parameters. This means that the result of the purchase will be returned to this listener. Then, we simply check if the purchase is null, and if not, award the user with whatever feature they bought.

Don’t let the listeners leak! We must destroy them when the app destroys.

@Override
public void onDestroy() {
    super.onDestroy();
    if (mHelper != null)
        try {
            mHelper.dispose();
            mHelper = null;

        } catch (IabHelper.IabAsyncInProgressException e) {
            e.printStackTrace();
        }
}

Finally, if you’d like to consume your purchase, making it available for purchase again, you can do so easily. An example of this is if a user bought gas for a virtual car, and it ran out. They need to purchase the same product again, and you can make it available for a second purchase by consuming it:

public void consume(){

    //MAKING A QUERY TO GET AN ACCURATE INVENTORY
    try {
        mHelper.flagEndAsync(); //If any async is going, make sure we have it stop eventually

        mHelper.queryInventoryAsync(mGotInventoryListener); //Getting inventory of purchases and assigning listener

        if(i.getPurchase("gas")==null){
            Toast.makeText(this, "Already consumed!", Toast.LENGTH_SHORT).show();
        }
    } catch (IabHelper.IabAsyncInProgressException e) {
        e.printStackTrace();

        Toast.makeText(this, "Error, try again", Toast.LENGTH_SHORT).show();
        mHelper.flagEndAsync();//If any async is going, make sure we have it stop eventually
    }

    //ACTUALLY CONSUMING
    try {
        mHelper.flagEndAsync();//If any async is going, make sure we have it stop eventually

        this.mHelper.consumeAsync(this.i.getPurchase("gas"), new IabHelper.OnConsumeFinishedListener() {
            public void onConsumeFinished(Purchase paramAnonymousPurchase, IabResult paramAnonymousIabResult) {
//resell the gas to them
            }
        });

        return;
    } catch (IabHelper.IabAsyncInProgressException localIabAsyncInProgressException) {
        localIabAsyncInProgressException.printStackTrace();
        Toast.makeText(this, "ASYNC IN PROGRESS ALREADY!!!!" +localIabAsyncInProgressException, Toast.LENGTH_LONG).show();
        Log.v("myTag", "ASYNC IN PROGRESS ALREADY!!!");

        mHelper.flagEndAsync();
    }
}

That’s it! You can now start making money. It’s really that simple!

Again, if you want a more detailed version of this tutorial, with screenshots and pictures, visit the original post here. Let me know in the comments if you have any more questions.