Developing for Android is really fun, as you have probably noticed if you want to have a wide user base you will have to give your application for free on the Android Market. From there, you have different way to monetize your application, you can limit features and unlock them in a payed version, display ads in free version and provide a way to disable ads (in-app purchase for example). In this article I will explain how to detect ad blocking in your applications.
Ad blocking ?
The way you try to monetize app will not be well accepted by everyone. Often, people use an Ad-Blocker (the same we know in web browsers) and will use the application for free as if they bought your ad free version. A rapid search on the Android market will point you to free application allowing to block ads on rooted devices.
The system is quite simple, it consists in blocking ads by
preventing DNS resolution process to work properly. Ads are loaded
from a certain website on the internet. The system does a DNS query
to resolve the IP adress of the remote site, the DNS resolution
process can be accelerated by setting entries in the hosts file
/etc/hosts under *nix and so Android). If the system
found a corresponding entry in the file, it does not waste time in
querying DNS servers and use the specified address.
You can find an example above,
blocked by making the system think the IP is the one corresponding
to the device.
I will explain by a few code snippets how to detect ad blocking using the AdMob SDK. The first thing to do is not bound to the use of AdMob, we will simply read and detect if your ad provider server is in the hosts file.
The code is pretty straightforward, the method takes a boolean parameter allowing to bypass checking, and checks if the keyword "admob" is present in the hosts file. The good thing is that it does not require any specific permission to read the hosts file where you have to request root to write to it.
To be efficient, you may want to check if ad blocking is enabled
only when there is an error in ad download. The Admob SDK provides a
convenient way to know when the download fail by implementing a
listener. You can find a simple implementation below, you will only
have to implements the behavior you want to adopt when ad blocking
is detected (
onAdBlocked()) and the logic to bypass
adblocker checking (
In your activity displaying ads, you just have to register the
listener in your
AdView and you're gone. The code
sample below shows how to do, feel free to nag your users and
pointing them to the in-app purchase or force them to quit (do it
every n-ad blocking).
That's all, you now have a simple way of detecting users using your applications without ads.