【起航计划 019】2015 起航计划 Android APIDemo的魔鬼步伐 18 App->Device Admin 设备管理器 DeviceAdminReceiver DevicePolicyManager PreferenceActivity的使用
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 /><!--
<force-lock />更改屏幕解锁密码
--><!-- 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
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