Friday, November 5, 2010

Developing a Device Administration Application

System administrators can use the Device Administration API to write an application that enforces remote/local device security policy enforcement. This section summarizes the steps involved in creating a device administration application.

Creating the manifest:
To use the Device Administration API, the application's manifest must include the following:

A subclass of DeviceAdminReceiver that includes the following:
--The BIND_DEVICE_ADMIN permission.
--The ability to respond to the ACTION_DEVICE_ADMIN_ENABLED intent, expressed in the manifest as an intent filter.

A declaration of security policies used in metadata.

Here is an snippet for the Device Administration sample manifest:


android:resource="@xml/device_admin_sample" />

Note that:

The activity in the sample application is an Activity subclass called Controller. The syntax ".app.DeviceAdminSample$Controller" indicates that Controller is an inner class that is nested inside the DeviceAdminSample class. Note that an Activity does not need to be an inner class; it just is in this example.

The following attributes refer to string resources that for the sample application reside in ApiDemos/res/values/strings.xml. For more information about resources, see Application Resources.

android:label="@string/activity_sample_device_admin" refers to the user-readable label for the activity.

android:label="@string/sample_device_admin" refers to the user-readable label for the permission.

android:description="@string/sample_device_admin_description" refers to the user-readable description of the permission. A descripton is typically longer and more informative than a label.

android:permission="android.permission.BIND_DEVICE_ADMIN" is a permission that a DeviceAdminReceiver subclass must have, to ensure that only the system can interact with the receiver (no application can be granted this permission). This prevents other applications from abusing your device admin app. is the the primary action that a DeviceAdminReceiver subclass must handle to be allowed to manage a device. This is set to the receiver when the user enables the device admin app. Your code typically handles this in onEnabled(). To be supported, the receiver must also require the BIND_DEVICE_ADMIN permission so that other applications cannot abuse it.

When a user enables the device admin application, that gives the receiver permission to perform actions in response to the broadcast of particular system events. When suitable event arises, the application can impose a policy. For example, if the user attempts to set a new password that doesn't meet the policy requirements, the application can prompt the user to pick a different password that does meet the requirements.

android:resource="@xml/device_admin_sample" declares the security policies used in metadata. The metadata provides additional information specific to the device administrator, as parsed by the DeviceAdminInfo class. Here are the contents of device_admin_sample.xml:

Implementing the code

The Device Administration API includes the following classes:


Base class for implementing a device administration component. This class provides a convenience for interpreting the raw intent actions that are sent by the system. Your Device Administration application must include a DeviceAdminReceiver subclass.

A class for managing policies enforced on a device. Most clients of this class must have published a DeviceAdminReceiver that the user has currently enabled. The DevicePolicyManager manages policies for one or more DeviceAdminReceiver instances

This class is used to specify metadata for a device administrator component.
These classes provide the foundation for a fully functional device administration application. The rest of this section describes how you use the DeviceAdminReceiver and DevicePolicyManager APIs to write a device admin application.

Subclassing DeviceAdminReceiver

To create a device admin application, you must subclass DeviceAdminReceiver. The DeviceAdminReceiver class consists of a series of callbacks that are triggered when particular events occur.

In its DeviceAdminReceiver subclass, the sample application simply displays a Toast notification in response to particular events. For example:

public class DeviceAdminSample extends DeviceAdminReceiver {

public void onEnabled(Context context, Intent intent) {
showToast(context, "Sample Device Admin: enabled");

public CharSequence onDisableRequested(Context context, Intent intent) {
return "This is an optional message to warn the user about disabling.";

public void onDisabled(Context context, Intent intent) {
showToast(context, "Sample Device Admin: disabled");

public void onPasswordChanged(Context context, Intent intent) {
showToast(context, "Sample Device Admin: pw changed");

void showToast(Context context, CharSequence msg) {
Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();

Enabling the application

One of the major events a device admin application has to handle is the user enabling the application. The user must explicitly enable the application for the policies to be enforced. If the user chooses not to enable the application it will still be present on the device, but its policies will not be enforced, and the user will not get any of the application's benefits.

The process of enabling the application begins when the user performs an action that triggers the ACTION_ADD_DEVICE_ADMIN intent. In the sample application, this happens when the user clicks the Enable Admin button

for Reference's Android Device Administration code

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