A simple app to reproduce the boot-loop issue on Lenovo TB3-850M (build TB3-850M_S100036_171214_ROW) when the DevicePolicyManager enforces DevicePolicyManager.addUserRestriction(admin, "no_usb_file_transfer") to prevent MTP file transfer usage.
Calling DevicePolicyManager.addUserRestriction(admin, "no_usb_file_transfer") actually stops the MTP feature on the device, but after that point whenever the device is shutdown it will not restart (boot-loop). A hard reset (POWER+ Vol-Down, then option "eMMC") of the tablet brings it back to life.
- Build the app (or use the APK provided here)
- Install on the target tablet. The tablet MUST BE WITHOUT ANY ACCOUNT INSTALLED, so the app can be set as DeviceOwner. If there is an account setup on the tablet (Google account for example), just do a factory reset first and install the APK just after.
- Set the sample app as DeviceOwner using adb:
adb shell dpm set-device-owner com.example.android.deviceowner/.DeviceOwnerReceiver
- Start the app ("DeviceOwner") and block USB File Transfer:
- Reboot.
Based on the sample by Google, with just a few lines added to add the feature "no_usb_file_transfer restriction":
This sample demonstrates how to use some device owner features. As a device owner, you can configure global settings such as automatic time and timezone. You can mandate a specific launcher by preferred intent handler.
In order to set global settings, use [DevicePolicyManager#setGlobalSetting][1] and specify one of the [Settings.Global][2] keys available. Note that you need to specify its value as a String. As most of the keys accept boolean values, you will mostly use "1" for true and "0" for false.
You can mandate a specific launcher by adding a persistent preferred activity for an IntentFilter with Intent.CATEGORY_HOME category. Call [DevicePolicyManager#addPersistentPreferredActivity][3] to register the activity. You can clear the registration with [clearPackagePersistentPreferredActivities][4].
As a device owner, you can also use the features available for managed profile owner. See [BasicManagedProfile][5].
[1]: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#setGlobalSetting(android.content.ComponentName, java.lang.String, java.lang.String) [2]: http://developer.android.com/reference/android/provider/Settings.Global.html [3]: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#addPersistentPreferredActivity(android.content.ComponentName, android.content.IntentFilter, android.content.ComponentName) [4]: http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#clearPackagePersistentPreferredActivities(android.content.ComponentName, java.lang.String) [5]: https://developer.android.com/samples/BasicManagedProfile/index.html
- Android SDK 27
- Android Build Tools v27.0.2
- Android Support Repository
This sample uses the Gradle build system. To build this project, use the "gradlew build" command or use "Import Project" in Android Studio.
- Google+ Community: https://plus.google.com/communities/105153134372062985968
- Stack Overflow: http://stackoverflow.com/questions/tagged/android
If you've found an error in this sample, please file an issue: https://github.com/googlesamples/android-DeviceOwner
Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub. Please see CONTRIBUTING.md for more details.
Copyright 2017 The Android Open Source Project, Inc.
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http://www.apache.org/licenses/LICENSE-2.0
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