How can I make it so a user can't delete a preinstalled Android app?

If I am an OEM making my own firmware and I want an app preinstalled on the device in a way that it can't be deleted, what do I need to do?

For example, suppose I make the ACME Gadget 2000, and when the user takes it out of the box it already has my app of Cats saying funny things, and I don't want the user to be able to delete it, what exactly do I have to do with the APK?

I have a Verizon Motorola Droid X开发者_如何转开发 and it comes with some apps on it that I can't delete. How do they DO that?

Thank you very much.

David

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OEM applications that are unremovable are installed to the /system/app directory (at least in every case I've ever seen, I suppose there may be exceptions). They cannot be uninstalled (sans rooting the device) because the /system partition is mounted read-only by default. I don't know of any way to design an .apk itself to be uninstallable since there are obviously significant security implications to allowing developers to do this.

Example mount listing from a Samsung Fascinate:

/dev/block/stl9 /system rfs ro,relatime,vfat,log_off,check=no,gid/uid/rwx,iochaset=utf8 0 0

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I mean it's a bit tricky but can be done. You have to allocate BroadcastReceiver, which triggered when occurs android.intent.action.PACKAGE_REMOVED, like:

 <receiver android:name ="com.mydomain.myapplication.PackageReceiver">
            <intent-filter>
              <action android:name="android.intent.action.PACKAGE_REMOVED"/>            
              <data android:scheme="package" />
            </intent-filter>
 </receiver>

And then when you will catch this Intent in your BroadcastReceiver - just cancel it. Well, probably you ought to define intent filter priority in a way to receive broadcast before others.

But problem is in simple fact that package which is going to be removed doesn't receive android.intent.action.PACKAGE_REMOVED. That means that you have to keep your own separate application/package which will have service observing who's gonna to uninstall your application.

That's general scheme - but in reality how it'd work - I dunno... Try!