Develop Reference

Install a GooglePlay located App from NFC

Working with Lollipop, I have a device-owner app that is installed with NFC at provision time.
What I need now is to handle automatic updates for my App, from Google Play to rely on the standard Android App update system...
So far I can imagine 2 ways to get this done, but don't know how to handle any of them :
in my NFC install constant EXTRA PROVISIONING DEVICE ADMIN PACKAGE
DOWNLOAD LOCATION install the App directly from the Play Store instead of the url on my own dev server. However
this constant need to handle the url of an apk file, and I did not find any
official way to get apk install direct from Play Store ? (as it will
be a production App in the future I'm not interested in hacks)
keep installing the apk from the dev server, but then allow the App
to update itself with its little brother located on the Play Store
with the same package name. To say it an other way: Would this be possible to install a v1 apk from a custom location, then put a v2 on the PlayStore... and let the magic come true ?
I'd be glad to hear if anyone could share experience about such procedures. Thanks for reading!
EDIT after #Stephan Branczyk suggestion I could make some more testing, here is what I did and the results:
1 - In the NFC provisioning I replaced the apk url with
snep://my.app.packagename without luck ; it just gives an error
without much explanation.
2 - I replaced this url by such a PlayStore link :
https://play.google.com/store/apps/details?id=my.app.packagename but
it gives a checksum error whether I use the checksum locally
computed, or the checksum given on the GooglePlay apk details. It looks not so far from the goal but I could not make it work.
3 - Finally I came back on my first solution, a self-hosted apk
versioned 1... but this time I tried to put on the PlayStore a newer
version 2 of the app with the exact same packagename... That led me
to strange things:
At first my App did not appear anywhere in the local PlayStore App,
but when I searched for it in Google Play, it showed up with the green
"installed" badge, and it proposed me to make an update... So did I.
Then, after this first manual update, the App is in v2, nice, and
better: it appears well listed in my PlayStore.
Optimistically, I uploaded a v3 of the App... just to see if my
PlayStore would automatically update my app (as is does for all the
other ones), but sadly no luck : even if my app is still listed in the
playstore, and proposing the "update" button... it never
updates by itself as it should ; I still need to click on it manually.
Isn't it a strange behavior ? If some have ideas about it, I would really need to be able to rely on the Play Store functionalities but so far no luck, and I cannot believe that Device-Owner app distribution is not compatible with PlayStore ?
Just in case, FYI here is the kind of provisioning code I'm using:
try {
Properties p = new Properties();
p.setProperty(
DevicePolicyManager.EXTRA_PROVISIONING_DEVICE_ADMIN_PACKAGE_NAME,
"my.app.packagename");
p.setProperty(
DevicePolicyManager.EXTRA_PROVISIONING_DEVICE_ADMIN_PACKAGE_DOWNLOAD_LOCATION,
"http://www.example.com/myDeviceOwnerApp.apk");
p.setProperty(
DevicePolicyManager.EXTRA_PROVISIONING_DEVICE_ADMIN_PACKAGE_CHECKSUM,
"U55o3fO0cXQtUoQCbQEO9c_gKrs");
ByteArrayOutputStream bos = new ByteArrayOutputStream();
OutputStream out = new ObjectOutputStream(bos);
p.store(out, "");
final byte[] bytes = bos.toByteArray();
NdefMessage msg = new NdefMessage(NdefRecord.createMime(
DevicePolicyManager.MIME_TYPE_PROVISIONING_NFC, bytes));
return msg;
} catch (Exception e) {
throw new RuntimeException(e);
}

Write your package name as an AAR record in the tag.
To confirm that this functionality works, use this app to write the tag with.

You need to set Base64 encoded SHA1 or SHA256 (from M forward) of the apk in the
EXTRA_PROVISIONING_DEVICE_ADMIN_PACKAGE_CHECKSUM
field when provisioning through NFC otherwise the provisioned device will not accept the URL for download.
Also see this answer for properly encoding the checksum.

Releasing packages on Play store

So, I have a fairly large app that I'd like to distribute via packages in the Play store. I see this tactic used quite often. I haven't seen much in the way of actually doing it. From what I've gathered so far the logic in code would work like this:
try {
Start activity in package
} catch (ActivityNotFoundException e) {
Prompt user to play store by using the package name as the URL
}
Aside from that, I'm wondering what kind of setup is required for the packages. They shouldn't be opened from a launcher (my app only).
What intent filters should the packages have applied to them if any?
Is it possible to set up the Manifest in such a way that I can make it unsearchable in Google Play but still be downloaded if linked directly to it?

"no activity found to handle intent" Not all phones have Android Market installed

Not all phones have Android Market installed, and therefore using intent to open market app fails.
What's the best way to handle this?
Hide this feature if user doesn't have Android Market installed (how would I detect this?).
Handle the possible error, how (and possibly suggest that the user downloads the Android Market)?

The problem with the answer above is that if you just pass a URL the user will be prompted how to handle the Intent.
A more graceful way to do it IMO, expanding upon the 1st answer above, is to test whether the market app is installed, and then if not, pass a URL (which actually you would then want to test to see if something can handle that intent, but if you happen to have a device without both the play store and a browser then I would question why the user would have my app installed in the first place (another story I suppose)....
Perhaps there is a better way, but here's what works for me:
private String getMarketURI(String marketURL) {
String returnURL = "";
PackageManager packageManager = getApplication().getPackageManager();
Uri marketUri = Uri.parse("market://" + marketURL);
Intent marketIntent = new Intent(Intent.ACTION_VIEW).setData(marketUri);
if (marketIntent.resolveActivity(packageManager) != null) {
returnURL = "market://" + marketURL;
} else {
returnURL = "https://play.google.com/store/apps/" + marketURL;
}
return returnURL;
}
And then use it like so:
marketIntent.setData(Uri.parse(getMarketURI("details?id=com.yourapps.packagename")));

If your app is being provided by Android Market, then it does have Android Market installed. :)
Okay that is snide, but there is an important truth -- Google goes to a lot of effort to enforce compatibility guarantees on devices for them to be allowed to ship with Android Market, so that is how you can know that whatever you are running on will behave as it should.
If you are delivering your app from something besides Android Market, you need to get information from whoever is delivering the app about what compatibility guarantees they have.
If they don't have compatibility guarantees (or you are just putting a raw .apk up on a web site or such), then you have a complete crap shoot. The device you are running on could have had its software modified in pretty much any way, and have any kind of differences in behavior you can imagine.
That said, if you want to determine whether there is an activity on the current device to handle a particular Intent, you can use this: PackageManager.resolveActivity

Use the web address as the intent target and then if there is no android market it will open in a browser.

Basic Android Licensing Enquiry

I am going to be sending off press-kits to various reviewers in regards to my new Android game and I am wondering how I should go about sending them an APK they can test? The game is paid and licensed.
If I send them the licensed version of the game they won't be able to run it on their phones without buying it. However, if I send them an unlicensed version and someone leaks it then everyone will just be able to get my game for free. What should I do?

Your options are pretty much limited to:
a time limited (demo) version
sending them an unlocked version which displays some personal information about the reviewer, thus making it in the reviewer's interests to keep the APK to themselves
using a licensing server. ie the game checks against a server (on GAE or similar) to see if it is allowed to run
I'm sure there are other options - I'd be interested to hear them.
One thing that is sorely missing from the Android Market is the ability to give the app to people. I think this is possible on the iOS store - at least like this you'd be able to grant real licences to the reviewers.

Following on from the above answers. Here's what I do (plus a message on the splash screen with the name of the reviewer)
private void initNewGame() {
//do a date check and quit if necessary
if ( reviewMode ) {
if ( new GregorianCalendar().after(new GregorianCalendar(2011,3,1,0,0,0))) {
//quit
((Program)parentActivity).finish();
}
}
}
I would also be interested if anyone has other ways of doing this, it's a really good question.

Make a free demo version that expires or something like that?

Auto-Update for (private) Android apps

I'm developing a non-public Android app, i.e. the app won't be available in the global Android Market. The app will be installed on a limited number of clients, e.g. by using an apk file.
How can I enable an auto-update functionality in this app?
I see different potential options (I do not know if those are technically hard or even impossible to implement or if there are any existing functionalities that can be reused):
On each launch the app tests if a new version exists (by requesting a server), if so downloads the new apk and replaces itself with the new version.
Use (or develop?) a separated app or service that undertakes the update-check and replacement-process.
Use (or develop?) a private market app which has an auto-update option. This option is similar to the second one, but more generic: The market app would be connected to a repository, i.e. it would handle an arbitrary number of (private) apps.
I would prefer option one since the auto-update functionality is included in the app which needs less development efforts.

janjonas, in the company I work we had a similar problem with Windows Mobile 6.x, and we use pretty much the same solution pointed by EboMike:
The main app check if it's updated, against a WebService. It receives the current version & the URL from where download the new version, if necessary. The main app then start the Updater app, passing the URL, and quit.
The Updater do the download of the new program, via HTTP, showing to the user the % downloaded. The user can cancel the download anytime, in a controlled way, and the Updater can registry this cancellation.
Since the new app is downloaded, the Updater run the new app, and quit.

I think option one is the least amount of work for you, and actually the cleanest one too since it will go through the proper channel of using Android's built-in package installer which includes user notification and the option for the user to abort the installation if desired.
You already have it all outlined - check for a new version on a server (would be nice to give the user the option to turn that off), and if there is a new version, you could either just link to the URL with the APK (which will, IIRC, use the browser's download manager to download it), or you could download it with your app and then point the intent to your local file. Using the HTTP link is technically less work and cleaner - the more you let the operating system do, the better - unless there's a reason not to.

Enabling "Install non-market app" is still needed for any application outside the Google Play. If it not enabled, the installation process is going to ask for it and redirect the user to the Application Settings, and after that, the user can install the app.
Depending on your needs, you can delegate to a third part lib.

Some of the permissions we'll use to get this done are the following:
<uses-permission android:name="android.permission.ACCESS_SUPERUSER" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
Let me explain a bit... The last, WRITE_EXTERNAL_STORAGE, is self-explanatory. With ACCESS_SUPERUSER we'll tell the system that we intend to use root privileges. READ_EXTERNAL_STORAGE will be needed in the future in order for your app to read files on SD card.
Assuming that you have downloaded the file and that all those devices can be rooted (limited number of clients, not on Play, etc.), you could do this:
String filePath = Environment.getExternalStorageDirectory().toString() + "/your_app_directory/your_app_filename.apk";
Process installProcess = null;
int installResult = -1337;
try {
installProcess = Runtime.getRuntime().exec("su -c pm install -r " + filePath);
} catch (IOException e) {
// Handle IOException the way you like.
}
if (installProcess != null) {
try {
installResult = installProcess.waitFor();
} catch(InterruptedException e) {
// Handle InterruptedException the way you like.
}
if (installResult == 0) {
// Success!
} else {
// Failure. :-/
}
} else {
// Failure 2. :-(
}

Here might be a very lame method but for some companies, if you believe its applicable, this might be very easy to implement.
Create an password screen (passwordActivity) that asks a password to access the application.
Once the password is entered, raise a flag (set a boolean value from false to true using sharedpreferences)
Place the .apk file on Google Store.
Change the password once everyone installs the app, and release a new update on Google Play Store.
Since the software is going to cache the flag value, the password screen won`t show up even the password is change. It will only show up for new installations so might need to repeat the process.
Note: This method might better fit if there is not hundreds of users using the application. And don`t forget this method is also not secure. To sum up, if you are looking a way to keep the application private and have no security concerns, this is what I recommend.

Update app
Make sure that you already have your new apk download on location
void installNewVersion(String location) {
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(new File(location + "app-debug.apk")),
"application/vnd.android.package-archive");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}