Device Admin示例介绍了类DeviceAdminReceiver，DevicePolicyManager和ActivityManager。
使用DevicePolicyManager这个类，这个类可以接管手机的应用权限，对手机做出很多大胆的操作，比如锁屏、恢复出厂设置、设置密码、强制清除密码，修改密码、设置屏幕灯光渐暗时间间隔等操作。
当它Publish在AndroidManifest.xml作为BroadcastReceiver定义时，必须处理 android.app.action.DEVICE_ADMIN_ENABLED和设置 android.permission.BIND_DEVICE_ADMIN权限，来监听权限的变化：
<receiver android:name=".app.DeviceAdminSample$DeviceAdminSampleReceiver"
android:label="@string/sample_device_admin"
android:description="@string/sample_device_admin_description"
android:permission="android.permission.BIND_DEVICE_ADMIN">
<meta-data android:name="android.app.device_admin"
android:resource="@xml/device_admin_sample" />
<intent-filter>
<action android:name="android.app.action.DEVICE_ADMIN_ENABLED" />
</intent-filter>
</receiver>
Android:permission 表示此功能需要的权限。
Android:name="android.app.action.DEVICE_ADMIN_ENABLED"表示此动作的跳转界面。
<meta-data android:name="android.app.device_admin" android:resource="@xml/device_admin_sample" />表示这个应用可以管理的权限清单，对应的device_admin_sample如下：
<device-admin xmlns:android="http://schemas.android.com/apk/res/android">
<uses-policies>
<limit-password /> <!-- 设置密码规则 所允许的长度和字符 -->
<watch-login /> <!-- 监视屏幕解锁尝试次数 -->
<reset-password /> <!-- 更改屏幕解锁密码 -->
<force-lock /> <!-- 强行锁屏-->
<wipe-data /> <!-- 清除所有数据（恢复出厂设置） -->
<expire-password /> <!-- 设置锁定屏幕密码的有效期 -->
<encrypted-storage /> <!-- 加密存储 指定要加密的存储位置-->
<disable-camera /> <!-- 禁用摄像头-->
<disable-keyguard-features /> <!--锁屏时禁用某些功能>
</uses-policies>
</device-admin>
在你设计你的设备管理程序时，并不需要包括所有的安全策略，按需定制即可。
更多WIKI见：链接
完成DeviceAdminReceiver的子类
要创建一个设备管理程序，就要实现一个继承DeviceAdminReceiver的类。DeviceAdminReceiver包含了一系列的回调函数，这些回调函数会在具体的事件发生时被调用。
在例子程序里，我们只是简单地显示了一个Toast，来做为对相应事件的应答。例如：
/**
* Sample implementation of a DeviceAdminReceiver. Your controller must provide one,
* although you may or may not implement all of the methods shown here.
*
* All callbacks are on the UI thread and your implementations should not engage in any
* blocking operations, including disk I/O.
*/
public static class DeviceAdminSampleReceiver extends DeviceAdminReceiver {
void showToast(Context context, String msg) {
String status = context.getString(R.string.admin_receiver_status, msg);
Toast.makeText(context, status, Toast.LENGTH_SHORT).show();
}
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction() == ACTION_DEVICE_ADMIN_DISABLE_REQUESTED) {
abortBroadcast();
}
super.onReceive(context, intent);
}
@Override
public void onEnabled(Context context, Intent intent) {
showToast(context, context.getString(R.string.admin_receiver_status_enabled));
}
@Override
public CharSequence onDisableRequested(Context context, Intent intent) {
return context.getString(R.string.admin_receiver_status_disable_warning);
}
@Override
public void onDisabled(Context context, Intent intent) {
showToast(context, context.getString(R.string.admin_receiver_status_disabled));
}
@Override
public void onPasswordChanged(Context context, Intent intent) {
showToast(context, context.getString(R.string.admin_receiver_status_pw_changed));
}
@Override
public void onPasswordFailed(Context context, Intent intent) {
showToast(context, context.getString(R.string.admin_receiver_status_pw_failed));
}
@Override
public void onPasswordSucceeded(Context context, Intent intent) {
showToast(context, context.getString(R.string.admin_receiver_status_pw_succeeded));
}
@Override
public void onPasswordExpiring(Context context, Intent intent) {
DevicePolicyManager dpm = (DevicePolicyManager) context.getSystemService(
Context.DEVICE_POLICY_SERVICE);
long expr = dpm.getPasswordExpiration(
new ComponentName(context, DeviceAdminSampleReceiver.class));
long delta = expr - System.currentTimeMillis();
boolean expired = delta < 0L;
String message = context.getString(expired ?
R.string.expiration_status_past : R.string.expiration_status_future);
showToast(context, message);
Log.v(TAG, message);
}
}
比如onPasswordExpiring中，当密码过期时，通过DevicePolicyManager的getPasswordExpiration方法获取过期的时间与当前时间对比。
DeviceAdminSample.java这个类继承自PreferenceActivity。
PreferenceActivity 继承自ListActivity 它是以一个列表的形式在展现内容，它最主要的特点是添加Preference可以让控件的状态持久化储存，举个例子 比如用户选中checkbox后 退出应用然后在进入应用，这时用户希望看到的是checkbox被选中，所以软件须要记录用户每次操作的过程并且持久储存，在进入应用的时候须要判断这些 久储存的数据然后将系统控件的状态呈现在UI中。
需要重写onBuilderHeaders来展示列表，loadHeadersFromResource是PreferenceActivity的方法，用来读取headers：
/**
* We override this method to provide PreferenceActivity with the top-level preference headers.
*/
@Override
public void onBuildHeaders(List<Header> target) {
loadHeadersFromResource(R.xml.device_admin_headers, target);
}
其中R.xml.device_admin_headers如下：
<!-- Headers for a set of preferences used to exercise the DevicePolicyManager API. -->
<preference-headers
xmlns:android="http://schemas.android.com/apk/res/android" >
<header
android:fragment="com.example.android.apis.app.DeviceAdminSample$GeneralFragment"
android:title="@string/header_general" />
<header
android:fragment="com.example.android.apis.app.DeviceAdminSample$QualityFragment"
android:title="@string/header_quality" />
<header
android:fragment="com.example.android.apis.app.DeviceAdminSample$ExpirationFragment"
android:title="@string/header_expiration" />
<header
android:fragment="com.example.android.apis.app.DeviceAdminSample$LockWipeFragment"
android:title="@string/header_lock_wipe" />
<header
android:fragment="com.example.android.apis.app.DeviceAdminSample$EncryptionFragment"
android:title="@string/header_encryption" />
</preference-headers>
点击各个条目会进入到对应的PreferenceFragment中：
这里先定义了一个基类AdminSampleFragment，它做了两件事：
1.提供context实例变量和DevicePolicyManager对象
2.针对多个fragment中存在的set password按钮的点击事件进行处理
/**
* Common fragment code for DevicePolicyManager access. Provides two shared elements:
*
* 1. Provides instance variables to access activity/context, DevicePolicyManager, etc.
* 2. Provides support for the "set password" button(s) shared by multiple fragments.
*/
public static class AdminSampleFragment extends PreferenceFragment
implements OnPreferenceChangeListener, OnPreferenceClickListener
接下来就是各个子PreferenceFragment了。
GeneralFragment
调用addPreferencesFromResource展示列表，findPreference获取各个列表对象并设置监听：
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.device_admin_general);
mEnableCheckbox = (CheckBoxPreference) findPreference(KEY_ENABLE_ADMIN);
mEnableCheckbox.setOnPreferenceChangeListener(this);
mDisableCameraCheckbox = (CheckBoxPreference) findPreference(KEY_DISABLE_CAMERA);
mDisableCameraCheckbox.setOnPreferenceChangeListener(this);
mDisableKeyguardWidgetsCheckbox =
(CheckBoxPreference) findPreference(KEY_DISABLE_KEYGUARD_WIDGETS);
mDisableKeyguardWidgetsCheckbox.setOnPreferenceChangeListener(this);
mDisableKeyguardSecureCameraCheckbox =
(CheckBoxPreference) findPreference(KEY_DISABLE_KEYGUARD_SECURE_CAMERA);
mDisableKeyguardSecureCameraCheckbox.setOnPreferenceChangeListener(this);
mDisableKeyguardNotificationCheckbox =
(CheckBoxPreference) findPreference(KEY_DISABLE_NOTIFICATIONS);
mDisableKeyguardNotificationCheckbox.setOnPreferenceChangeListener(this);
mDisableKeyguardUnredactedCheckbox =
(CheckBoxPreference) findPreference(KEY_DISABLE_UNREDACTED);
mDisableKeyguardUnredactedCheckbox.setOnPreferenceChangeListener(this);
mDisableKeyguardTrustAgentCheckbox =
(CheckBoxPreference) findPreference(KEY_DISABLE_TRUST_AGENTS);
mDisableKeyguardTrustAgentCheckbox.setOnPreferenceChangeListener(this);
}
对应的PreferenceScreen布局如下：
<!-- A set of preferences used to exercise the DevicePolicyManager API. -->
<!-- This screen is shown for the "General" header. -->
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android" >
<PreferenceCategory
android:title="@string/enable_admin" >
<CheckBoxPreference
android:key="key_enable_admin"
android:title="@string/enable_admin" />
</PreferenceCategory>
<PreferenceCategory
android:title="@string/device_capabilities_category" >
<CheckBoxPreference
android:key="key_disable_camera"
android:title="@string/disable_camera" />
<CheckBoxPreference
android:key="key_disable_keyguard_widgets"
android:title="@string/disable_keyguard_widgets" />
<CheckBoxPreference
android:key="key_disable_keyguard_secure_camera"
android:title="@string/disable_keyguard_secure_camera" />
<CheckBoxPreference
android:key="key_disable_notifications"
android:title="@string/disable_keyguard_notifications" />
<CheckBoxPreference
android:key="key_disable_unredacted"
android:title="@string/disable_keyguard_unredacted_notifications" />
<CheckBoxPreference
android:key="key_disable_trust_agents"
android:title="@string/disable_keyguard_trust_agents" />
</PreferenceCategory>
</PreferenceScreen>
PreferenceScreen：代表显示一整个屏幕
PreferenceCategory：内部嵌套PreferenceCategory标签，表示偏好类别，在PreferenceCategory标签内部可以随便存放复选框CheckBoxPreference，输入框EditTextPreference，列表ListPreference等显示控件
CheckBoxPreference：复选框控件
其他组件见：链接
当用户点击了Enable Admin 选择框，设备就会提示用户已经启用了设备管理程序,
下面就是当用户点击了 Enable Admin 选择框要执行的代码。效果是触发了onPreferenceChange()回调函数。当用户改变Preference的值时，就会调用这个回调函数。如果用户启用程序，界面就会提示用户正在启用程序，否则就是禁止程序：
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
if (super.onPreferenceChange(preference, newValue)) {
return true;
}
boolean value = (Boolean) newValue;
if (preference == mEnableCheckbox) {
if (value != mAdminActive) {
if (value) {
// Launch the activity to have the user enable our admin.
Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, mDeviceAdminSample);
intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,
mActivity.getString(R.string.add_admin_extra_app_text));
startActivityForResult(intent, REQUEST_CODE_ENABLE_ADMIN);
// return false - don‘t update checkbox until we‘re really active
return false;
} else {
mDPM.removeActiveAdmin(mDeviceAdminSample);
enableDeviceCapabilitiesArea(false);
mAdminActive = false;
}
}
} else if (preference == mDisableCameraCheckbox) {
mDPM.setCameraDisabled(mDeviceAdminSample, value);
...
}
return true;
}
当程序要执行一个操作，它要确定管理程序是否已经被启用了。实现的方法就是使用DevicePolicyManager的isAdminActive()方法。要注意的是，DevicePolicyManager的isAdminActive()方法需要一个DeviceAdminReceiver类型的参数。
DevicePolicyManager mDPM;
...
private boolean isActiveAdmin() {
return mDPM.isAdminActive(mDeviceAdminSample);
}
其他管理策略的代码请见链接的4.2.3管理策略：链接
时间： 2024-11-06 10:15:20