分析Android 11.0Settings源碼之主界面加載
本篇主要記錄AndroidR Settings源碼主界面加載流程，方便後續工作調試其流程。
Settings代碼路徑：
packages/app/Settings/
Settings代碼獲取：
Setting 源碼下載地址：https://github.com/aosp-mirror/platform_packages_apps_settings
git地址：https://github.com/aosp-mirror/platform_packages_apps_settings.git
主界面加載：
首先我們來看 Settings 模塊中的 AndroidManifest.xml 文件，找到默認啟動入口Activity信息：
<activity android:name=".homepage.SettingsHomepageActivity"
android:label="@string/settings_label_launcher"
android:theme="@style/Theme.Settings.Home"
android:taskAffinity="com.android.settings.root"
android:launchMode="singleTask"
android:configChanges="keyboard|keyboardHidden">
<intent-filter android:priority="1">
<action android:name="android.settings.SETTINGS" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
<meta-data android:name="com.android.settings.PRIMARY_PROFILE_CONTROLLED"
android:value="true" />
</activity>
//activity-alias可用來設置某個Activity的快捷入口，可以放在桌面上或者通過該別名被其他組件快速調起。
//android:targetActivity為目標Activity.
<!-- Alias for launcher activity only, as this belongs to each profile. -->
<activity-alias android:name="Settings"
android:label="@string/settings_label_launcher"
android:taskAffinity="com.android.settings.root"
android:launchMode="singleTask"
android:targetActivity=".homepage.SettingsHomepageActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<meta-data android:name="android.app.shortcuts" android:resource="@xml/shortcuts"/>
</activity-alias>
可以看到Settings的桌面圖標啟動的主界面是Settings.java，但其xml定義瞭targetActivity屬性，實質應是SettingsHomepageActivity.java，從onCreate()方法開始:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.settings_homepage_container);
final View root = findViewById(R.id.settings_homepage_container);
root.setSystemUiVisibility(
View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
setHomepageContainerPaddingTop();
final Toolbar toolbar = findViewById(R.id.search_action_bar);
FeatureFactory.getFactory(this).getSearchFeatureProvider()
.initSearchToolbar(this /* activity */, toolbar, SettingsEnums.SETTINGS_HOMEPAGE);
final ImageView avatarView = findViewById(R.id.account_avatar);
getLifecycle().addObserver(new AvatarViewMixin(this, avatarView));
getLifecycle().addObserver(new HideNonSystemOverlayMixin(this));
if (!getSystemService(ActivityManager.class).isLowRamDevice()) {
// Only allow contextual feature on high ram devices.
showFragment(new ContextualCardsFragment(), R.id.contextual_cards_content);
}
showFragment(new TopLevelSettings(), R.id.main_content);
((FrameLayout) findViewById(R.id.main_content))
.getLayoutTransition().enableTransitionType(LayoutTransition.CHANGING);
}
可以看到主界面的layout為settings_homepage_container.xml:
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/settings_homepage_container"
android:fitsSystemWindows="true"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.core.widget.NestedScrollView
android:id="@+id/main_content_scrollable_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="com.android.settings.widget.FloatingAppBarScrollingViewBehavior">
<LinearLayout
android:id="@+id/homepage_container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<FrameLayout
android:id="@+id/contextual_cards_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/contextual_card_side_margin"
android:layout_marginEnd="@dimen/contextual_card_side_margin"/>
<FrameLayout
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:animateLayoutChanges="true"
android:background="?android:attr/windowBackground"/>
</LinearLayout>
</androidx.core.widget.NestedScrollView>
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:touchscreenBlocksFocus="false"
android:keyboardNavigationCluster="false">
<include layout="@layout/search_bar"/>
</com.google.android.material.appbar.AppBarLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
主界面佈局中主要包含兩部分：一個頂部快捷搜索欄，一個Id為main_content的FrameLayout就是用來顯示主設置內容的，即Settings的一級菜單項界面。
回到onCreate()方法：
showFragment(new TopLevelSettings(), R.id.main_content);
可以看到一級菜單啟動的是TopLevelSettings，TopLevelSettings繼承於DashboardFragment.java：
public class TopLevelSettings extends DashboardFragment implements PreferenceFragmentCompat.OnPreferenceStartFragmentCallback
TopLevelSettings的構造方法：
public TopLevelSettings() {
final Bundle args = new Bundle();
// Disable the search icon because this page uses a full search view in actionbar.
args.putBoolean(NEED_SEARCH_ICON_IN_ACTION_BAR, false);
setArguments(args);
}
可以看到通過構造方法傳遞瞭一個參數，從註釋中可以看出，該參數的用意是由於主界面使用完整的搜索視圖所以在主界面的actionbar中隱藏瞭搜索圖標。然後再根據framgments生命周期先來看onAttach()方法:
@Override
public void onAttach(Context context) {
super.onAttach(context);
use(SupportPreferenceController.class).setActivity(getActivity());
}
調用父類DashboardFragment.java的onAttach()方法：
@Override
public void onAttach(Context context) {
super.onAttach(context);
mSuppressInjectedTileKeys = Arrays.asList(context.getResources().getStringArray(
R.array.config_suppress_injected_tile_keys));
mDashboardFeatureProvider = FeatureFactory.getFactory(context).
getDashboardFeatureProvider(context);
// Load preference controllers from code
final List<AbstractPreferenceController> controllersFromCode =
createPreferenceControllers(context);
// Load preference controllers from xml definition
final List<BasePreferenceController> controllersFromXml = PreferenceControllerListHelper
.getPreferenceControllersFromXml(context, getPreferenceScreenResId());
// Filter xml-based controllers in case a similar controller is created from code already.
final List<BasePreferenceController> uniqueControllerFromXml =
PreferenceControllerListHelper.filterControllers(
controllersFromXml, controllersFromCode);
// Add unique controllers to list.
if (controllersFromCode != null) {
mControllers.addAll(controllersFromCode);
}
mControllers.addAll(uniqueControllerFromXml);
// And wire up with lifecycle.
final Lifecycle lifecycle = getSettingsLifecycle();
uniqueControllerFromXml.forEach(controller -> {
if (controller instanceof LifecycleObserver) {
lifecycle.addObserver((LifecycleObserver) controller);
}
});
// Set metrics category for BasePreferenceController.
final int metricCategory = getMetricsCategory();
mControllers.forEach(controller -> {
if (controller instanceof BasePreferenceController) {
((BasePreferenceController) controller).setMetricsCategory(metricCategory);
}
});
mPlaceholderPreferenceController =
new DashboardTilePlaceholderPreferenceController(context);
mControllers.add(mPlaceholderPreferenceController);
for (AbstractPreferenceController controller : mControllers) {
addPreferenceController(controller);
}
}
通過方法註釋可以得知此方法主要是完成preference controllers的加載。
DashboardFragment.java的onCreate()方法：
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// Set ComparisonCallback so we get better animation when list changes.
getPreferenceManager().setPreferenceComparisonCallback(
new PreferenceManager.SimplePreferenceComparisonCallback());
if (icicle != null) {
// Upon rotation configuration change we need to update preference states before any
// editing dialog is recreated (that would happen before onResume is called).
updatePreferenceStates();
}
}
設置ComparisonCallback，以便在列表更改時獲得更好的動畫效果。
第一次進入時，icicle為null，根據log定位發現，其後調用DashboardFragment.java的onCreatePreferences()方法：
@Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
checkUiBlocker(mControllers);
refreshAllPreferences(getLogTag());
mControllers.stream()
.map(controller -> (Preference) findPreference(controller.getPreferenceKey()))
.filter(Objects::nonNull)
.forEach(preference -> {
// Give all controllers a chance to handle click.
preference.getExtras().putInt(CATEGORY, getMetricsCategory());
});
}
調用refreshAllPreferences()：
/**
* Refresh all preference items, including both static prefs from xml, and dynamic items from
* DashboardCategory.
*/
private void refreshAllPreferences(final String tag) {
final PreferenceScreen screen = getPreferenceScreen();
// First remove old preferences.
if (screen != null) {
// Intentionally do not cache PreferenceScreen because it will be recreated later.
screen.removeAll();
}
// Add resource based tiles.
displayResourceTiles();
refreshDashboardTiles(tag);
final Activity activity = getActivity();
if (activity != null) {
Log.d(tag, "All preferences added, reporting fully drawn");
activity.reportFullyDrawn();
}
updatePreferenceVisibility(mPreferenceControllers);
}
刷新所有preference items，包括來自xml的靜態preference和來自DashboardCategory的動態preference，靜態xml定義的prefs(調用displayResourceTiles()方法)，動態DashboardCategory動態加載(調用refreshDashboardTiles(TAG)方法，其中TAG為 “TopLevelSettings”)。
displayResourceTiles()：此方法主要是從xml資源文件中加載顯示prefs：
/**
* Displays resource based tiles.
*/
private void displayResourceTiles() {
final int resId = getPreferenceScreenResId();
if (resId <= 0) {
return;
}
addPreferencesFromResource(resId);
final PreferenceScreen screen = getPreferenceScreen();
screen.setOnExpandButtonClickListener(this);
displayResourceTilesToScreen(screen);
}
/**
* Perform {@link AbstractPreferenceController#displayPreference(PreferenceScreen)}
* on all {@link AbstractPreferenceController}s.
*/
protected void displayResourceTilesToScreen(PreferenceScreen screen) {
mPreferenceControllers.values().stream().flatMap(Collection::stream).forEach(
controller -> controller.displayPreference(screen));
}
靜態加載
首先調用getPreferenceScreenResId()方法獲取所要加載的xml的ID，然後調用子類TopLevelSettings.java的getPreferenceScreenResId()方法：
@Override
protected int getPreferenceScreenResId() {
return R.xml.top_level_settings;
}
可以看到Settings主界面加載的xml文件是top_level_settings：
<PreferenceScreen
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:settings="http://schemas.android.com/apk/res-auto"
android:key="top_level_settings">
<Preference
android:key="top_level_network"
android:title="@string/network_dashboard_title"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_network"
android:order="-120"
android:fragment="com.android.settings.network.NetworkDashboardFragment"
settings:controller="com.android.settings.network.TopLevelNetworkEntryPreferenceController"/>
<Preference
android:key="top_level_connected_devices"
android:title="@string/connected_devices_dashboard_title"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_connected_device"
android:order="-110"
android:fragment="com.android.settings.connecteddevice.ConnectedDeviceDashboardFragment"
settings:controller="com.android.settings.connecteddevice.TopLevelConnectedDevicesPreferenceController"/>
<Preference
android:key="top_level_apps_and_notifs"
android:title="@string/app_and_notification_dashboard_title"
android:summary="@string/app_and_notification_dashboard_summary"
android:icon="@drawable/ic_homepage_apps"
android:order="-100"
android:fragment="com.android.settings.applications.AppAndNotificationDashboardFragment"/>
<Preference
android:key="top_level_battery"
android:title="@string/power_usage_summary_title"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_battery"
android:fragment="com.android.settings.fuelgauge.PowerUsageSummary"
android:order="-90"
settings:controller="com.android.settings.fuelgauge.TopLevelBatteryPreferenceController"/>
<Preference
android:key="top_level_display"
android:title="@string/display_settings"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_display"
android:order="-80"
android:fragment="com.android.settings.DisplaySettings"
settings:controller="com.android.settings.display.TopLevelDisplayPreferenceController"/>
<Preference
android:key="top_level_sound"
android:title="@string/sound_settings"
android:summary="@string/sound_dashboard_summary"
android:icon="@drawable/ic_homepage_sound"
android:order="-70"
android:fragment="com.android.settings.notification.SoundSettings"/>
<Preference
android:key="top_level_storage"
android:title="@string/storage_settings"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_storage"
android:order="-60"
android:fragment="com.android.settings.deviceinfo.StorageSettings"
settings:controller="com.android.settings.deviceinfo.TopLevelStoragePreferenceController"/>
<Preference
android:key="top_level_privacy"
android:title="@string/privacy_dashboard_title"
android:summary="@string/privacy_dashboard_summary"
android:icon="@drawable/ic_homepage_privacy"
android:order="-55"
android:fragment="com.android.settings.privacy.PrivacyDashboardFragment"/>
<Preference
android:key="top_level_location"
android:title="@string/location_settings_title"
android:summary="@string/location_settings_loading_app_permission_stats"
android:icon="@drawable/ic_homepage_location"
android:order="-50"
android:fragment="com.android.settings.location.LocationSettings"
settings:controller="com.android.settings.location.TopLevelLocationPreferenceController"/>
<Preference
android:key="top_level_security"
android:title="@string/security_settings_title"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_security"
android:order="-40"
android:fragment="com.android.settings.security.SecuritySettings"
settings:controller="com.android.settings.security.TopLevelSecurityEntryPreferenceController"/>
<Preference
android:key="top_level_accounts"
android:title="@string/account_dashboard_title"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_accounts"
android:order="-30"
android:fragment="com.android.settings.accounts.AccountDashboardFragment"
settings:controller="com.android.settings.accounts.TopLevelAccountEntryPreferenceController"/>
<Preference
android:key="top_level_accessibility"
android:title="@string/accessibility_settings"
android:summary="@string/accessibility_settings_summary"
android:icon="@drawable/ic_homepage_accessibility"
android:order="-20"
android:fragment="com.android.settings.accessibility.AccessibilitySettings"
settings:controller="com.android.settings.accessibility.TopLevelAccessibilityPreferenceController"/>
<Preference
android:key="top_level_system"
android:title="@string/header_category_system"
android:summary="@string/system_dashboard_summary"
android:icon="@drawable/ic_homepage_system_dashboard"
android:order="10"
android:fragment="com.android.settings.system.SystemDashboardFragment"/>
<Preference
android:key="top_level_about_device"
android:title="@string/about_settings"
android:summary="@string/summary_placeholder"
android:icon="@drawable/ic_homepage_about"
android:order="20"
android:fragment="com.android.settings.deviceinfo.aboutphone.MyDeviceInfoFragment"
settings:controller="com.android.settings.deviceinfo.aboutphone.TopLevelAboutDevicePreferenceController"/>
<Preference
android:key="top_level_support"
android:summary="@string/support_summary"
android:title="@string/page_tab_title_support"
android:icon="@drawable/ic_homepage_support"
android:order="100"
settings:controller="com.android.settings.support.SupportPreferenceController"/>
</PreferenceScreen>
可以看到主要配置的是一些Preference菜單項如網絡和互聯網、已連接的設備、應用和通知、電池等等，Preference的配置含義：
- key：唯一性ID；
- title：標題；
- summary：簡介；
- ico：圖標；
- order：加載顯示優先級，order為負時，絕對值越高，界面顯示越靠前；order為正時，值越高，顯示越靠後；
- fragment：點擊此preference所跳轉的fragment界面；
- controller：控制管理類。
動態加載
refreshDashboardTiles
總結：
- Settings的主Activity實質實現是在SettingsHomepageActivity.java內；
- Settings的主界面設置item的顯示是在fragment上，fragment為TopLevelSettings.java，加載顯示的佈局為top_level_settings.xml；
- Settings主界面設置項item的加載顯示主要分為兩部分，一部分是xml定義的靜態加載，xml為top_level_settings.xml；一部分是DashboardCategory來獲取動態加載；
- 每個設置項item均為一個preference，通過xml定義加載時，必須要有一個controller，可以是在xml中定義”settings:controller”屬性聲明，名稱必須與類的包名路徑相同；也可直接在相關fragment中實現createPreferenceControllers()方法去調用構造相關controller。此二者存其一即可。
- xml中配置preference時，必須定義”android:key“屬性；
以上就是分析Android 11.0Settings源碼之主界面加載的詳細內容，更多關於Android 11.0Settings源碼的資料請關註WalkonNet其它相關文章！
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