Android 8.0 Settings流程分析与变动
开! 场! 白! 好! 难! 写!
一,相比Android Settings 7.0
如下图,在7.0的基础上,去掉了7.0新加的侧滑菜单(可能是觉得有点鸡肋吧)。多加了一级页面,把原来类别标题变成的第一级菜单的子项。在代码架构也稍加变动,并引入架构组件之LifeCycle(生命周期感知,本文不作介绍)。
二,第一级菜单的加载
浏览源码,大多数我们从程序的AndroidManifest.xml入手,这次也不列外。
packages\apps\Settings\AndroidManifest.xml:
<activity-alias android:name="Settings"
android:taskAffinity="com.android.settings"
android:label="@string/settings_label_launcher"
android:launchMode="singleTask"
android:targetActivity="Settings">
<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>
找到<category android:name="android.intent.category.LAUNCHER" />所属的类,Settings.java。但打开Settings.java类看,除了大量静态类继承SettingsActivity,就没什么东西了。那再去父类SettingsActivity.java找找。
packages\apps\Settings\src\com\android\settings\SettingsActivity.java:
首先当然是onCreate()->
@Override
protected void onCreate(Bundle savedState) {
super.onCreate(savedState);
long startTime = System.currentTimeMillis();
//工厂类实现方法com.android.settings.overlay.FeatureFactoryImpl.java
final FeatureFactory factory = FeatureFactory.getFactory(this);
//获取菜单信息的工厂类,实现类为DashboardFeatureProviderImpl.java
mDashboardFeatureProvider = factory.getDashboardFeatureProvider(this);
mMetricsFeatureProvider = factory.getMetricsFeatureProvider();
// 从intent信息中获取<meta-data/>标签名为"com.android.settings.FRAGMENT_CLASS"的值(下文用于加载Fragment的类名)
getMetaData();
... ...
//获取上面getMetaData()得到的类名
final String initialFragmentName = intent.getStringExtra(EXTRA_SHOW_FRAGMENT);
//是否为快捷进入方式(如从其它的应用进入Settings的某个设置项)
mIsShortcut = isShortCutIntent(intent) || isLikeShortCutIntent(intent) ||
intent.getBooleanExtra(EXTRA_SHOW_FRAGMENT_AS_SHORTCUT, false);
... ...
//当前类是否为Settings.class,即进入方式为点击launcher上的图标进入的主设置界面
mIsShowingDashboard = className.equals(Settings.class.getName());
... ...
setContentView(mIsShowingDashboard ?
R.layout.settings_main_dashboard : R.layout.settings_main_prefs);
mContent = findViewById(R.id.main_content);
getFragmentManager().addOnBackStackChangedListener(this);
if (savedState != null) {
... ...
} else {
//加载布局
launchSettingFragment(initialFragmentName, isSubSettings, intent);
}
... ...
}
launchSettingFragment()->
@VisibleForTesting
void launchSettingFragment(String initialFragmentName, boolean isSubSettings, Intent intent) {
if (!mIsShowingDashboard && initialFragmentName != null) {
... ...
switchToFragment(initialFragmentName, initialArguments, true, false,
mInitialTitleResId, mInitialTitle, false);
} else {
// Show search icon as up affordance if we are displaying the main Dashboard
mDisplayHomeAsUpEnabled = true;
mInitialTitleResId = R.string.dashboard_title;
//进入主页走的这里,替换目标Fragment
switchToFragment(DashboardSummary.class.getName(), null /* args */, false, false,
mInitialTitleResId, mInitialTitle, false);
}
}
继续,我们看看DashboardSummary.java,对于它我们主要是想知道它的数据加载,它是怎么加载自己的子项的。
packages\apps\Settings\src\com\android\settings\dashboard\DashboardSummary.java:
对子项的数据获取在updateCategoryAndSuggestion()中得到实现。
@VisibleForTesting
void updateCategoryAndSuggestion(List<Tile> suggestions) {
final Activity activity = getActivity();
if (activity == null) {
return;
}
/*根据"com.android.settings.category"的值查询子项数据,这里的值为"com.android.settings.category.ia.homepage"。
具体获取办法追踪到frameworks\base\packages\SettingsLib\src\com\android\settingslib\drawer\TileUtils.java中。
通过PackageManager查询所有在AndroidManifest.xml中定义<meta-data/>中含有该值的类。注意:会过滤掉非系统级应用的数据!
有兴趣的自行研究,这里不深究。*/
final DashboardCategory category = mDashboardFeatureProvider.getTilesForCategory(
CategoryKey.CATEGORY_HOMEPAGE);
if (category == null) {
return;
}
mSummaryLoader.updateSummaryToCache(category);
if (suggestions != null) {
mAdapter.setCategoriesAndSuggestions(category, suggestions);
} else {
//数据的绑定在适配器中,->packages\apps\Settings\src\com\android\settings\dashboard\DashboardAdapter.java
mAdapter.setCategory(category);
}
}
对于第一级菜单的加载。在AndroidManifest.xml中的配置如下列图:
三,第二级菜单的加载
以上我们知道第一级菜单是完全动态的加载,但二级菜单则是动态加载和静态xml布局文件,就拿“系统”这项为例。
packages\apps\Settings\AndroidManifest.xml:
<activity android:name=".Settings$SystemDashboardActivity"
android:label="@string/header_category_system"
android:icon="@drawable/ic_settings_about">
<intent-filter android:priority="-1">
<action android:name="com.android.settings.action.SETTINGS"/>
</intent-filter>
<meta-data android:name="com.android.settings.category"
android:value="com.android.settings.category.ia.homepage"/>
<meta-data android:name="com.android.settings.FRAGMENT_CLASS"
android:value="com.android.settings.system.SystemDashboardFragment"/>
<meta-data android:name="com.android.settings.summary"
android:resource="@string/system_dashboard_summary"/>
</activity>
SystemDashboardFragment.java继承DashboardFragment.java。我们主要观察这个类。
packages\apps\Settings\src\com\android\settings\dashboard\DashboardFragment.java:
1,静态加载部分:
静态加载部分的实现方法为displayResourceTiles()->
/**
* Displays resource based tiles.
*/
private void displayResourceTiles() {
//获取xml布局文件的id(DashboardFragment.java实现该方法)
final int resId = getPreferenceScreenResId();
if (resId <= 0) {
return;
}
addPreferencesFromResource(resId);
final PreferenceScreen screen = getPreferenceScreen();
/** 实现布局文件中的子项控件的业务逻辑
* DashboardFragment.java的子类实现getPreferenceControllers()方法,该方法加载继承于AbstractPreferenceController.java的实现业务逻辑类
*/
Collection<AbstractPreferenceController> controllers = mPreferenceControllers.values();
for (AbstractPreferenceController controller : controllers) {
controller.displayPreference(screen);
}
}
2,动态加载部分:
动态加载部分的实现方法refreshDashboardTiles()->
/**
* Refresh preference items backed by DashboardCategory.
*/
@VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
void refreshDashboardTiles(final String TAG) {
final PreferenceScreen screen = getPreferenceScreen();
/* 获取子项
* getCategoryKey()从DashboardFragmentRegistry.PARENT_TO_CATEGORY_KEY_MAP中获取Category值。
* 该值通过类名获取
* 存:PARENT_TO_CATEGORY_KEY_MAP.put(SystemDashboardFragment.class.getName(), CategoryKey.CATEGORY_SYSTEM);
* CATEGORY_SYSTEM = "com.android.settings.category.ia.system";
*/
final DashboardCategory category =
mDashboardFeatureProvider.getTilesForCategory(getCategoryKey());
... ...
// Install dashboard tiles.
for (Tile tile : tiles) {
... ...
if (mDashboardTilePrefKeys.contains(key)) {
... ...
} else {
// Don't have this key, add it.
final Preference pref = new Preference(getPrefContext());
/*在这里进行绑定,加载
*packages\apps\Settings\src\com\android\settings\dashboard\DashboardFeatureProviderImpl.java->bindPreferenceToTile()
*/
mDashboardFeatureProvider.bindPreferenceToTile(getActivity(), getMetricsCategory(),
pref, tile, key, mPlaceholderPreferenceController.getOrder());
mProgressiveDisclosureMixin.addPreference(screen, pref);
mDashboardTilePrefKeys.add(key);
}
remove.remove(key);
}
// Finally remove tiles that are gone.
for (String key : remove) {
mDashboardTilePrefKeys.remove(key);
mProgressiveDisclosureMixin.removePreference(screen, key);
}
mSummaryLoader.setListening(true);
}
该文的Settings加载流程就差不多到这里了。
四,顺便说说
下拉菜单栏时长按设置图标进入设置,在系统项里面会多一个《系统界面调节工具》。那么这是怎么显示和隐藏的了?
frameworks\base\packages\SystemUI\src\com\android\systemui\tuner\TunerService.java
->setTunerEnabled():
public static final void setTunerEnabled(Context context, boolean enabled) {
//隐藏应用图标,隐藏某个组件启动也可以使用该方法
userContext(context).getPackageManager().setComponentEnabledSetting(
new ComponentName(context, TunerActivity.class),
enabled ? PackageManager.COMPONENT_ENABLED_STATE_ENABLED
: PackageManager.COMPONENT_ENABLED_STATE_DISABLED,
PackageManager.DONT_KILL_APP);
}