前言

上一篇我们具体分析了SystemUI的启动流程，在SystemServer的startOtherServices方法中，会启动SystemUIService服务，SystemUIService服务的onCreate方法会继续调用SystemUIApplication的startServicesIfNeeded方法，在该方法中会获取SystemUI组件各个类的具体路径，并通过和dagger2相关的ComponentHelper关键接口，获取SystemUI组件对应的实例对象，然后依次调用每个组件的start() 方法启动相关类的服务，启动完成后，又会再次调用该组件的onBootCompleted( ) 方法。

frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIApplication.java

    private void startServicesIfNeeded(String metricsPrefix, String[] services) {if (mServicesStarted) {//如果服务已经启动直接返回return;}mServices = new SystemUI[services.length];...代码省略...     final int N = services.length;for (int i = 0; i < N; i++) {String clsName = services[i];//具体SystemUI组件类的完整路径long ti = System.currentTimeMillis();try {SystemUI obj = mComponentHelper.resolveSystemUI(clsName);//ComponentHelper的resolveSystemUI方法可以通过类名拿到具体的SystemUI实例对象if (obj == null) {//如果通过ComponentHelper的resolveSystemUI没有成功获取到实例对象，则通过反射创建，代码基本上不会走这里。Constructor constructor = Class.forName(clsName).getConstructor(Context.class);obj = (SystemUI) constructor.newInstance(this);//通过反射创建实例对象}mServices[i] = obj;//将获取的obj实例对象赋值到数组中。} catch (ClassNotFoundException| NoSuchMethodException| IllegalAccessException| InstantiationException| InvocationTargetException ex) {throw new RuntimeException(ex);}...代码省略...     mServices[i].start();...代码省略...     if (mBootCompleteCache.isBootComplete()) {mServices[i].onBootCompleted();}...代码省略...     }...代码省略...   mServicesStarted = true;//服务已经被启动}

frameworks/base/packages/SystemUI/res/values/config.xml

    <string-array name="config_systemUIServiceComponents" translatable="false"><item>com.android.systemui.util.NotificationChannels</item><!--通知--><item>com.android.systemui.keyguard.KeyguardViewMediator</item><!--键盘锁状态--><item>com.android.systemui.recents.Recents</item><!--任务列表--><item>com.android.systemui.volume.VolumeUI</item><!--监听音量，并决定是否显示音量的对话框--><item>com.android.systemui.statusbar.phone.StatusBar</item><!--状态栏--><item>com.android.systemui.usb.StorageNotification</item><!--监听 USB 连接状态并发送通知进行提示--><item>com.android.systemui.power.PowerUI</item><!--监听电量状态并在低电量时发送通知--><item>com.android.systemui.media.RingtonePlayer</item><!--用于播放铃声--><item>com.android.systemui.keyboard.KeyboardUI</item><!--键盘锁 UI--><item>com.android.systemui.shortcut.ShortcutKeyDispatcher</item><!--快捷分发器--><item>@string/config_systemUIVendorServiceComponent</item><!--这里可以定义厂商定制的组件--><item>com.android.systemui.util.leak.GarbageMonitor$Service</item><!--用于监控内存泄漏的服务--><item>com.android.systemui.LatencyTester</item><!--仅在 debug 环境执行，用于监听系统测试延迟的模拟动作--><item>com.android.systemui.globalactions.GlobalActionsComponent</item><!--用于显示全局对话框（例如长按电源按键）--><item>com.android.systemui.ScreenDecorations</item><!--处理页面中的显示的形状（如圆角）--><item>com.android.systemui.biometrics.AuthController</item><!--身份验证--><item>com.android.systemui.SliceBroadcastRelayHandler</item><!--允许打开设置App--><item>com.android.systemui.statusbar.notification.InstantAppNotifier</item><!--时应用程序通知--><item>com.android.systemui.theme.ThemeOverlayController</item><!--主题--><item>com.android.systemui.accessibility.WindowMagnification</item><!--放大器--><item>com.android.systemui.accessibility.SystemActions</item><item>com.android.systemui.toast.ToastUI</item><item>com.android.systemui.wmshell.WMShell</item></string-array>

本篇文章我们主要来分析一下com.android.systemui.statusbar.phone.StatusBar所对应的状态栏类的创建过程。

一、StatusBar的构造方法

1、通过前面的分析我们知道，SystemUI的所有组件实例都是通过和dagger2相关的ComponentHelper类得到的，该类中的的SystemUI组件实例最初是通过dagger2的依赖注入得到的，而dagger2在实例化SystemUI组件的时候，会调用对应组件的构造方法，StatusBar的构造方法如下所示：

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBar.java

public class StatusBar extends SystemUI implements ActivityStarter, LifecycleOwner {public StatusBar(Context context,NotificationsController notificationsController,FragmentService fragmentService,LightBarController lightBarController,AutoHideController autoHideController,StatusBarWindowController statusBarWindowController,//状态栏控制器KeyguardUpdateMonitor keyguardUpdateMonitor,StatusBarSignalPolicy statusBarSignalPolicy,PulseExpansionHandler pulseExpansionHandler,NotificationWakeUpCoordinator notificationWakeUpCoordinator,KeyguardBypassController keyguardBypassController,KeyguardStateController keyguardStateController,HeadsUpManagerPhone headsUpManagerPhone,DynamicPrivacyController dynamicPrivacyController,BypassHeadsUpNotifier bypassHeadsUpNotifier,FalsingManager falsingManager,FalsingCollector falsingCollector,BroadcastDispatcher broadcastDispatcher,NotifShadeEventSource notifShadeEventSource,NotificationEntryManager notificationEntryManager,NotificationGutsManager notificationGutsManager,NotificationLogger notificationLogger,NotificationInterruptStateProvider notificationInterruptStateProvider,NotificationViewHierarchyManager notificationViewHierarchyManager,PanelExpansionStateManager panelExpansionStateManager,KeyguardViewMediator keyguardViewMediator,DisplayMetrics displayMetrics,MetricsLogger metricsLogger,@UiBackground Executor uiBgExecutor,NotificationMediaManager notificationMediaManager,NotificationLockscreenUserManager lockScreenUserManager,NotificationRemoteInputManager remoteInputManager,UserSwitcherController userSwitcherController,NetworkController networkController,BatteryController batteryController,SysuiColorExtractor colorExtractor,ScreenLifecycle screenLifecycle,WakefulnessLifecycle wakefulnessLifecycle,SysuiStatusBarStateController statusBarStateController,Optional<BubblesManager> bubblesManagerOptional,Optional<Bubbles> bubblesOptional,VisualStabilityManager visualStabilityManager,DeviceProvisionedController deviceProvisionedController,NavigationBarController navigationBarController,AccessibilityFloatingMenuController accessibilityFloatingMenuController,Lazy<AssistManager> assistManagerLazy,ConfigurationController configurationController,NotificationShadeWindowController notificationShadeWindowController,DozeParameters dozeParameters,ScrimController scrimController,Lazy<LockscreenWallpaper> lockscreenWallpaperLazy,LockscreenGestureLogger lockscreenGestureLogger,Lazy<BiometricUnlockController> biometricUnlockControllerLazy,DozeServiceHost dozeServiceHost,PowerManager powerManager,ScreenPinningRequest screenPinningRequest,DozeScrimController dozeScrimController,VolumeComponent volumeComponent,CommandQueue commandQueue,CollapsedStatusBarFragmentLogger collapsedStatusBarFragmentLogger,StatusBarComponent.Factory statusBarComponentFactory,//状态栏组件工厂PluginManager pluginManager,Optional<LegacySplitScreen> splitScreenOptional,LightsOutNotifController lightsOutNotifController,StatusBarNotificationActivityStarter.BuilderstatusBarNotificationActivityStarterBuilder,ShadeController shadeController,StatusBarKeyguardViewManager statusBarKeyguardViewManager,ViewMediatorCallback viewMediatorCallback,InitController initController,@Named(TIME_TICK_HANDLER_NAME) Handler timeTickHandler,PluginDependencyProvider pluginDependencyProvider,KeyguardDismissUtil keyguardDismissUtil,ExtensionController extensionController,UserInfoControllerImpl userInfoControllerImpl,OperatorNameViewController.Factory operatorNameViewControllerFactory,PhoneStatusBarPolicy phoneStatusBarPolicy,KeyguardIndicationController keyguardIndicationController,DemoModeController demoModeController,Lazy<NotificationShadeDepthController> notificationShadeDepthControllerLazy,StatusBarTouchableRegionManager statusBarTouchableRegionManager,NotificationIconAreaController notificationIconAreaController,BrightnessSliderController.Factory brightnessSliderFactory,WallpaperController wallpaperController,OngoingCallController ongoingCallController,SystemStatusAnimationScheduler animationScheduler,StatusBarLocationPublisher locationPublisher,StatusBarIconController statusBarIconController,StatusBarHideIconsForBouncerManager statusBarHideIconsForBouncerManager,LockscreenShadeTransitionController lockscreenShadeTransitionController,FeatureFlags featureFlags,KeyguardUnlockAnimationController keyguardUnlockAnimationController,@Main Handler mainHandler,@Main DelayableExecutor delayableExecutor,@Main MessageRouter messageRouter,WallpaperManager wallpaperManager,UnlockedScreenOffAnimationController unlockedScreenOffAnimationController,Optional<StartingSurface> startingSurfaceOptional,TunerService tunerService,DumpManager dumpManager,ActivityLaunchAnimator activityLaunchAnimator) {super(context);mNotificationsController = notificationsController;mFragmentService = fragmentService;mLightBarController = lightBarController;mAutoHideController = autoHideController;mStatusBarWindowController = statusBarWindowController;mKeyguardUpdateMonitor = keyguardUpdateMonitor;mPulseExpansionHandler = pulseExpansionHandler;mWakeUpCoordinator = notificationWakeUpCoordinator;mKeyguardBypassController = keyguardBypassController;mKeyguardStateController = keyguardStateController;mHeadsUpManager = headsUpManagerPhone;mOperatorNameViewControllerFactory = operatorNameViewControllerFactory;mKeyguardIndicationController = keyguardIndicationController;mStatusBarTouchableRegionManager = statusBarTouchableRegionManager;mDynamicPrivacyController = dynamicPrivacyController;mBypassHeadsUpNotifier = bypassHeadsUpNotifier;mFalsingCollector = falsingCollector;mFalsingManager = falsingManager;mBroadcastDispatcher = broadcastDispatcher;mNotifShadeEventSource = notifShadeEventSource;mEntryManager = notificationEntryManager;mGutsManager = notificationGutsManager;mNotificationLogger = notificationLogger;mNotificationInterruptStateProvider = notificationInterruptStateProvider;mViewHierarchyManager = notificationViewHierarchyManager;mPanelExpansionStateManager = panelExpansionStateManager;mKeyguardViewMediator = keyguardViewMediator;mDisplayMetrics = displayMetrics;mMetricsLogger = metricsLogger;mUiBgExecutor = uiBgExecutor;mMediaManager = notificationMediaManager;mLockscreenUserManager = lockScreenUserManager;mRemoteInputManager = remoteInputManager;mUserSwitcherController = userSwitcherController;mNetworkController = networkController;mBatteryController = batteryController;mColorExtractor = colorExtractor;mScreenLifecycle = screenLifecycle;mWakefulnessLifecycle = wakefulnessLifecycle;mStatusBarStateController = statusBarStateController;mBubblesManagerOptional = bubblesManagerOptional;mBubblesOptional = bubblesOptional;mVisualStabilityManager = visualStabilityManager;mDeviceProvisionedController = deviceProvisionedController;mNavigationBarController = navigationBarController;mAccessibilityFloatingMenuController = accessibilityFloatingMenuController;mAssistManagerLazy = assistManagerLazy;mConfigurationController = configurationController;mNotificationShadeWindowController = notificationShadeWindowController;mDozeServiceHost = dozeServiceHost;mPowerManager = powerManager;mDozeParameters = dozeParameters;mScrimController = scrimController;mLockscreenWallpaperLazy = lockscreenWallpaperLazy;mLockscreenGestureLogger = lockscreenGestureLogger;mScreenPinningRequest = screenPinningRequest;mDozeScrimController = dozeScrimController;mBiometricUnlockControllerLazy = biometricUnlockControllerLazy;mNotificationShadeDepthControllerLazy = notificationShadeDepthControllerLazy;mVolumeComponent = volumeComponent;mCommandQueue = commandQueue;mCollapsedStatusBarFragmentLogger = collapsedStatusBarFragmentLogger;mStatusBarComponentFactory = statusBarComponentFactory;mPluginManager = pluginManager;mSplitScreenOptional = splitScreenOptional;mStatusBarNotificationActivityStarterBuilder = statusBarNotificationActivityStarterBuilder;mShadeController = shadeController;mLightsOutNotifController =  lightsOutNotifController;mStatusBarKeyguardViewManager = statusBarKeyguardViewManager;mKeyguardViewMediatorCallback = viewMediatorCallback;mInitController = initController;mPluginDependencyProvider = pluginDependencyProvider;mKeyguardDismissUtil = keyguardDismissUtil;mExtensionController = extensionController;mUserInfoControllerImpl = userInfoControllerImpl;mIconPolicy = phoneStatusBarPolicy;mDemoModeController = demoModeController;mNotificationIconAreaController = notificationIconAreaController;mBrightnessSliderFactory = brightnessSliderFactory;mWallpaperController = wallpaperController;mOngoingCallController = ongoingCallController;mAnimationScheduler = animationScheduler;mStatusBarSignalPolicy = statusBarSignalPolicy;mStatusBarLocationPublisher = locationPublisher;mStatusBarIconController = statusBarIconController;mStatusBarHideIconsForBouncerManager = statusBarHideIconsForBouncerManager;mFeatureFlags = featureFlags;mKeyguardUnlockAnimationController = keyguardUnlockAnimationController;mMainHandler = mainHandler;mMainExecutor = delayableExecutor;mMessageRouter = messageRouter;mWallpaperManager = wallpaperManager;mUnlockedScreenOffAnimationController = unlockedScreenOffAnimationController;mTunerService = tunerService;mLockscreenShadeTransitionController = lockscreenShadeTransitionController;mStartingSurfaceOptional = startingSurfaceOptional;lockscreenShadeTransitionController.setStatusbar(this);mPanelExpansionStateManager.addExpansionListener(this::onPanelExpansionChanged);mBubbleExpandListener =(isExpanding, key) -> mContext.getMainExecutor().execute(() -> {mNotificationsController.requestNotificationUpdate("onBubbleExpandChanged");updateScrimController();});mActivityIntentHelper = new ActivityIntentHelper(mContext);mActivityLaunchAnimator = activityLaunchAnimator;// The status bar background may need updating when the ongoing call status changes.mOngoingCallController.addCallback((animate) -> maybeUpdateBarMode());// TODO(b/190746471): Find a better home for this.DateTimeView.setReceiverHandler(timeTickHandler);mMessageRouter.subscribeTo(KeyboardShortcutsMessage.class,data -> toggleKeyboardShortcuts(data.mDeviceId));mMessageRouter.subscribeTo(MSG_DISMISS_KEYBOARD_SHORTCUTS_MENU,id -> dismissKeyboardShortcuts());mMessageRouter.subscribeTo(AnimateExpandSettingsPanelMessage.class,data -> mCommandQueueCallbacks.animateExpandSettingsPanel(data.mSubpanel));mMessageRouter.subscribeTo(MSG_LAUNCH_TRANSITION_TIMEOUT,id -> onLaunchTransitionTimeout());}}

StatusBar的构造方法乍一看简直恐怖如斯，因为它的参数居然足足有100多个，这种代码要是放在以前，肯定妥妥的被骂翻！构造方法参数如此之多别人要如何创建对象实例？幸好现在有了Dagger2框架的加持，该框架会自动帮我们创建对象实例并传入StatusBar需要的所有参数，我们直接在StatusBar中用就是了，所以构造方法就算有再多参数也不是什么大问题了。

二、从StatusBar的start方法到状态栏视图窗口StatusBarWindowView的创建

1、结合前面SystemUIApplication的startServicesIfNeeded方法我们知道，在获得每个SystemUI组件对象之后，都会调用该对象的start方法，作为SystemUI组件之一的StatusBar自然也不例外：

public class StatusBar extends SystemUI implements ActivityStarter, LifecycleOwner {@Overridepublic void start() {...代码省略...createAndAddWindows(result);...代码省略...}
}

start方法会调用一个叫createAndAddWindows的关键方法，系统状态栏视图的创建和添加工作就是在该方法中完成的。

2、和createAndAddWindows方法相关的代码如下所示：

public class StatusBar extends SystemUI implements ActivityStarter, LifecycleOwner {private final StatusBarWindowController mStatusBarWindowController;//状态栏窗口控制器private final StatusBarComponent.Factory mStatusBarComponentFactory;//Dagger2状态栏组件工厂private StatusBarComponent mStatusBarComponent;//Dagger2状态栏子组件protected PhoneStatusBarView mStatusBarView;//状态栏视图private PhoneStatusBarViewController mPhoneStatusBarViewController;//状态栏视图控制器public StatusBar(...代码省略...StatusBarWindowController statusBarWindowController,//状态栏控制器StatusBarComponent.Factory statusBarComponentFactory,//状态栏Dagger2组件工厂...代码省略...){...代码省略...//为状态栏控制器mStatusBarWindowController赋值mStatusBarWindowController = statusBarWindowController;//为状态栏Dagger2组件工厂mStatusBarComponentFactory赋值mStatusBarComponentFactory = statusBarComponentFactory;...代码省略...}   @Overridepublic void start() {...代码省略...createAndAddWindows(result);...代码省略...}public void createAndAddWindows(@Nullable RegisterStatusBarResult result) {makeStatusBarView(result);...代码省略...mStatusBarWindowController.attach();}protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {...代码省略...inflateStatusBarWindow();...代码省略...mStatusBarWindowController.getFragmentHostManager().addTagListener(CollapsedStatusBarFragment.TAG, (tag, fragment) -> {代码省略}).getFragmentManager().beginTransaction().replace(R.id.status_bar_container,mStatusBarComponent.createCollapsedStatusBarFragment(),CollapsedStatusBarFragment.TAG).commit();...代码省略...}private void inflateStatusBarWindow() {mStatusBarComponent = mStatusBarComponentFactory.create();...代码省略...}
}

1）StatusBar的构造方法会为状态栏窗口控制器mStatusBarWindowController和Dagger2状态栏组件工厂mStatusBarComponentFactory对象赋值。createAndAddWindows首先调用了makeStatusBarView方法来构建视图，makeStatusBarView方法又会调用inflateStatusBarWindow方法，inflateStatusBarWindow方法内部又调用mStatusBarComponentFactory的create方法为Dagger2状态栏组件mStatusBarComponent赋值。等inflateStatusBarWindow方法执行完毕，makeStatusBarView方法会调用mStatusBarWindowController的getFragmentHostManager来获取FragmentHostManager对象实例。

2）StatusBarWindowController和getFragmentHostManager方法相关的代码如下所示：

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarWindowController.java

@SysUISingleton
public class StatusBarWindowController {@Injectpublic StatusBarWindowController(Context context,@StatusBarWindowModule.InternalWindowView StatusBarWindowView statusBarWindowView,WindowManager windowManager,IWindowManager iWindowManager,StatusBarContentInsetsProvider contentInsetsProvider,@Main Resources resources) {...代码省略...mStatusBarWindowView = statusBarWindowView;...代码省略...}public FragmentHostManager getFragmentHostManager() {return FragmentHostManager.get(mStatusBarWindowView);}
}

getFragmentHostManager内部会将mStatusBarWindowView作为唯一参数，继续调用FragmentHostManager的get方法。

frameworks/base/packages/SystemUI/src/com/android/systemui/fragments/FragmentHostManager.java

public class FragmentHostManager {public static FragmentHostManager get(View view) {try {return Dependency.get(FragmentService.class).getFragmentHostManager(view);} catch (ClassCastException e) {// TODO: Some auto handling here?throw e;}}
}

FragmentHostManager的get方法继续调用FragmentService的getFragmentHostManager方法。

public class FragmentService implements Dumpable {public FragmentHostManager getFragmentHostManager(View view) {View root = view.getRootView();FragmentHostState state = mHosts.get(root);if (state == null) {//创建FragmentHostState对象实例state = new FragmentHostState(root);mHosts.put(root, state);}//调用FragmentHostState的getFragmentHostManager方法return state.getFragmentHostManager();} private class FragmentHostState {private final View mView;private FragmentHostManager mFragmentHostManager;public FragmentHostState(View view) {mView = view;//创建FragmentHostManager对象实例mFragmentHostManager = new FragmentHostManager(FragmentService.this, mView);}public FragmentHostManager getFragmentHostManager() {return mFragmentHostManager;}}
}

FragmentService的getFragmentHostManager会创建FragmentHostState对象实例，然后调用该对象的getFragmentHostManager方法，该方法会返回mFragmentHostManager，而mFragmentHostManager最早是在FragmentHostState自己的构造方法中创建的，原来绕了一圈，最后得到的结果其实就是，StatusBarWindowController的getFragmentHostManager方法会将StatusBarWindowView作为构造方法参数创建FragmentHostManager实例对象。

public class FragmentHostManager {private final View mRootView;FragmentHostManager(FragmentService manager, View rootView) {...代码省略...//将StatusBarWindowView赋值给mRootView mRootView = rootView;...代码省略...}

由于后续会用到mRootView，这里我们就有必要看一下StatusBarWindowView的来源了，因为需要知道其对应的布局文件。

3）StatusBarWindowController最早是被dagger2依赖注入到StatusBar中的，作为构造方法参数的StatusBarWindowView，也是被Dagger2依赖注入到StatusBarWindowController中的。Dagger2获取StatusBarWindowView对象实例的关键代码位于StatusBarWindowModule的providesStatusBarWindowView方法中：

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/window/StatusBarWindowModule.kt

@Module
abstract class StatusBarWindowModule {@Modulecompanion object {//提供一个单例的StatusBarWindowView对象实例@JvmStatic@Provides@SysUISingleton@InternalWindowViewfun providesStatusBarWindowView(layoutInflater: LayoutInflater): StatusBarWindowView {return layoutInflater.inflate(R.layout.super_status_bar,/* root= */null) as StatusBarWindowView??: throw IllegalStateException("R.layout.super_status_bar could not be properly inflated")}}}

providesStatusBarWindowView直接将super_status_bar.xml布局文件转化为View对象，然后再将View转化为StatusBarWindowView进行返回，其中的super_status_bar.xml布局文件内容如下所示：

frameworks/base/packages/SystemUI/res/layout/super_status_bar.xml

<com.android.systemui.statusbar.window.StatusBarWindowViewxmlns:android="http://schemas.android.com/apk/res/android"xmlns:sysui="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"android:fitsSystemWindows="true"><FrameLayoutandroid:id="@+id/status_bar_launch_animation_container"android:layout_width="match_parent"android:layout_height="match_parent" /><FrameLayoutandroid:id="@+id/status_bar_container"android:layout_width="match_parent"android:layout_height="wrap_content"android:background="@drawable/system_bar_background" />
</com.android.systemui.statusbar.window.StatusBarWindowView>

根控件是StatusBarWindowView，正是我们之前多次提到的状态栏窗口对象，其内部有两个FrameLayout，id为status_bar_launch_animation_container的FrameLayout主要是负责状态栏打开其他Activity时候的切换动画，id为status_bar_container的FrameLayout则是承载状态栏视图内容的容器。

三、创建状态栏视图CollapsedStatusBarFragment

1、继续来看在StatusBar的makeStatusBarView方法。

   protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {...代码省略...mStatusBarWindowController.getFragmentHostManager().addTagListener(CollapsedStatusBarFragment.TAG, (tag, fragment) -> {代码省略}).getFragmentManager().beginTransaction().replace(R.id.status_bar_container,mStatusBarComponent.createCollapsedStatusBarFragment(),CollapsedStatusBarFragment.TAG).commit();...代码省略...}

在调用StatusBarWindowController的getFragmentHostManager获得FragmentHostManager实例对象之后，会继续调用addTagListener方法设置监听对象，然后获取FragmentManager并开启会话，再调用mStatusBarComponent的createCollapsedStatusBarFragment方法创建状态栏视图的CollapsedStatusBarFragment，将其对应的视图设置到id为status_bar_container的控件上。

2、StatusBarComponent和创建CollapsedStatusBarFragment对象实例有关的代码如下所示：

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/dagger/StatusBarComponent.java

@Subcomponent(modules = {StatusBarViewModule.class})
@StatusBarComponent.StatusBarScope
public interface StatusBarComponent {/*** Builder for {@link StatusBarComponent}.*/@Subcomponent.Factoryinterface Factory {StatusBarComponent create();}/*** Scope annotation for singleton items within the StatusBarComponent.*/@Documented@Retention(RUNTIME)@Scope@interface StatusBarScope {}/*** 每次被调用的时候会创建一个新的CollapsedStatusBarFragment实例对象*/CollapsedStatusBarFragment createCollapsedStatusBarFragment();
}

对java来说StatusBarComponent是一个接口，其内部的Factory对应了我们前面提到的状态栏组件工厂mStatusBarComponentFactory；而对于dagger2来说，StatusBarComponent是一个子连接器，且存在一个模块StatusBarViewModule。

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/dagger/StatusBarViewModule.java

@Module(subcomponents = StatusBarFragmentComponent.class)
public abstract class StatusBarViewModule {public static CollapsedStatusBarFragment createCollapsedStatusBarFragment(StatusBarFragmentComponent.Factory statusBarFragmentComponentFactory,OngoingCallController ongoingCallController,SystemStatusAnimationScheduler animationScheduler,StatusBarLocationPublisher locationPublisher,NotificationIconAreaController notificationIconAreaController,PanelExpansionStateManager panelExpansionStateManager,FeatureFlags featureFlags,StatusBarIconController statusBarIconController,StatusBarHideIconsForBouncerManager statusBarHideIconsForBouncerManager,KeyguardStateController keyguardStateController,NotificationPanelViewController notificationPanelViewController,NetworkController networkController,StatusBarStateController statusBarStateController,CommandQueue commandQueue,CollapsedStatusBarFragmentLogger collapsedStatusBarFragmentLogger,OperatorNameViewController.Factory operatorNameViewControllerFactory,SecureSettings secureSettings,@Main Executor mainExecutor) {return new CollapsedStatusBarFragment(statusBarFragmentComponentFactory,ongoingCallController,animationScheduler,locationPublisher,notificationIconAreaController,panelExpansionStateManager,featureFlags,statusBarIconController,statusBarHideIconsForBouncerManager,keyguardStateController,notificationPanelViewController,networkController,statusBarStateController,commandQueue,collapsedStatusBarFragmentLogger,operatorNameViewControllerFactory,secureSettings,mainExecutor);}
}

在StatusBarViewModule的createCollapsedStatusBarFragment方法内部创建了CollapsedStatusBarFragment对象实例，StatusBarComponent的createCollapsedStatusBarFragment最终触发的其实就是这个方法。

3、前面提到FragmentHostManager有调用addTagListener方法为设置监听对象，该监听对象的回调方法会在CollapsedStatusBarFragment的onViewCreated方法执行之后被调用。

   protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {...代码省略...mStatusBarWindowController.getFragmentHostManager().addTagListener(CollapsedStatusBarFragment.TAG, (tag, fragment) -> {StatusBarFragmentComponent statusBarFragmentComponent =((CollapsedStatusBarFragment) fragment).getStatusBarFragmentComponent();if (statusBarFragmentComponent == null) {throw new IllegalStateException("CollapsedStatusBarFragment should have a valid component");}//状态栏视图mStatusBarView = statusBarFragmentComponent.getPhoneStatusBarView();//状态栏视图控制器mPhoneStatusBarViewController =statusBarFragmentComponent.getPhoneStatusBarViewController();mNotificationPanelViewController.updatePanelExpansionAndVisibility();setBouncerShowingForStatusBarComponents(mBouncerShowing);mLightsOutNotifController.setLightsOutNotifView(mStatusBarView.findViewById(R.id.notification_lights_out));//为通知栏遮罩窗口控制器设置状态栏mNotificationShadeWindowViewController.setStatusBarView(mStatusBarView);checkBarModes();}).getFragmentManager().beginTransaction().replace(R.id.status_bar_container,mStatusBarComponent.createCollapsedStatusBarFragment(),CollapsedStatusBarFragment.TAG).commit();...代码省略...}

回调方法中首先将状态栏视图保存到mStatusBarView中，状态栏视图控制器保存到mPhoneStatusBarViewController 中，然后让状态栏视图和通知栏相关的类进行了一定的关联。

四、状态栏视图结构分析

1、CollapsedStatusBarFragment的代码很多，我们这里只讲一下它初始化布局文件的代码。

frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/fragment/CollapsedStatusBarFragment.java

public class CollapsedStatusBarFragment extends Fragment implements CommandQueue.Callbacks,StatusBarStateController.StateListener,SystemStatusAnimationCallback {@Overridepublic View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,Bundle savedInstanceState) {return inflater.inflate(R.layout.status_bar, container, false);}
}

可以看到状态栏视图所对应的布局文件为status_bar.xml，该布局文件对应了系统状态栏所的视图内容。

frameworks/base/packages/SystemUI/res/layout/status_bar.xml

<com.android.systemui.statusbar.phone.PhoneStatusBarViewxmlns:android="http://schemas.android.com/apk/res/android"xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui"android:layout_width="match_parent"android:layout_height="@dimen/status_bar_height"android:id="@+id/status_bar"android:orientation="vertical"android:focusable="false"android:descendantFocusability="afterDescendants"android:accessibilityPaneTitle="@string/status_bar"><!--是否有新通知的标志--><ImageViewandroid:id="@+id/notification_lights_out"android:layout_width="@dimen/status_bar_icon_size"android:layout_height="match_parent"android:paddingStart="@dimen/status_bar_padding_start"android:paddingBottom="2dip"android:src="@drawable/ic_sysbar_lights_out_dot_small"android:scaleType="center"android:visibility="gone"/><!--状态栏视图--><LinearLayout android:id="@+id/status_bar_contents"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingStart="@dimen/status_bar_padding_start"android:paddingEnd="@dimen/status_bar_padding_end"android:paddingTop="@dimen/status_bar_padding_top"android:orientation="horizontal"><FrameLayoutandroid:layout_height="match_parent"android:layout_width="0dp"android:layout_weight="1"><include layout="@layout/heads_up_status_bar_layout" /><!-- The alpha of the left side is controlled by PhoneStatusBarTransitions, and theindividual views are controlled by StatusBarManager disable flags DISABLE_CLOCK andDISABLE_NOTIFICATION_ICONS, respectively --><LinearLayoutandroid:id="@+id/status_bar_left_side"android:layout_height="match_parent"android:layout_width="match_parent"android:clipChildren="false"><!--延时启动，设备用户名称--><ViewStubandroid:id="@+id/operator_name"android:layout_width="wrap_content"android:layout_height="match_parent"android:layout="@layout/operator_name" /><!--时钟--><com.android.systemui.statusbar.policy.Clockandroid:id="@+id/clock"android:layout_width="wrap_content"android:layout_height="match_parent"android:textAppearance="@style/TextAppearance.StatusBar.Clock"android:singleLine="true"android:paddingStart="@dimen/status_bar_left_clock_starting_padding"android:paddingEnd="@dimen/status_bar_left_clock_end_padding"android:gravity="center_vertical|start"/><!--正在进行的电话--><include layout="@layout/ongoing_call_chip" /><!--下拉通知页面图标区域--><com.android.systemui.statusbar.AlphaOptimizedFrameLayoutandroid:id="@+id/notification_icon_area"android:layout_width="0dp"android:layout_height="match_parent"android:layout_weight="1"android:orientation="horizontal"android:clipChildren="false"/></LinearLayout></FrameLayout><!-- Space should cover the notch (if it exists) and let other views lay out around it --><android.widget.Spaceandroid:id="@+id/cutout_space_view"android:layout_width="0dp"android:layout_height="match_parent"android:gravity="center_horizontal|center_vertical"/><!--下拉通知页面的中心图标区域--><com.android.systemui.statusbar.AlphaOptimizedFrameLayoutandroid:id="@+id/centered_icon_area"android:layout_width="wrap_content"android:layout_height="match_parent"android:orientation="horizontal"android:clipChildren="false"android:gravity="center_horizontal|center_vertical"/><!--状态栏系统图标区域--><com.android.keyguard.AlphaOptimizedLinearLayoutandroid:id="@+id/system_icon_area"android:layout_width="0dp"android:layout_height="match_parent"android:layout_weight="1"android:orientation="horizontal"android:gravity="center_vertical|end"><!--系统图标--><include layout="@layout/system_icons" /></com.android.keyguard.AlphaOptimizedLinearLayout></LinearLayout><!--延迟加载 紧急电话文字--><ViewStubandroid:id="@+id/emergency_cryptkeeper_text"android:layout_width="wrap_content"android:layout_height="match_parent"android:layout="@layout/emergency_cryptkeeper_text"/></com.android.systemui.statusbar.phone.PhoneStatusBarView>

1）根控件是PhoneStatusBarView，其内部包含了状态栏的所有视图内容，大致结构如下所示。

2）下面是HierarchyViewer关于系统状态栏的一张视图结构分析图，基本可以对应上status_bar.xml布局文件。

五、将状态栏窗口添加到Window中

1、StatusBar的createAndAddWindows方法在调用makeStatusBarView方法构建好状态栏视图之后，便会调用StatusBarWindowController的attach方法。

public class StatusBar extends SystemUI implements ActivityStarter, LifecycleOwner {public void createAndAddWindows(@Nullable RegisterStatusBarResult result) {makeStatusBarView(result);...代码省略...mStatusBarWindowController.attach();}

2、StatusBarWindowController的attach方法方法如下所示：

@SysUISingleton
public class StatusBarWindowController {private final WindowManager mWindowManager;private WindowManager.LayoutParams mLp;@Injectpublic StatusBarWindowController(Context context,@StatusBarWindowModule.InternalWindowView StatusBarWindowView statusBarWindowView,WindowManager windowManager,IWindowManager iWindowManager,StatusBarContentInsetsProvider contentInsetsProvider,@Main Resources resources) {...代码省略...mWindowManager = windowManager;mStatusBarWindowView = statusBarWindowView;if (mBarHeight < 0) {mBarHeight = SystemBarUtils.getStatusBarHeight(mContext);}}public void attach() {//获取状态栏类型窗口所需要的布局参数mLp = getBarLayoutParams(mContext.getDisplay().getRotation());//调用WindowManager的addView方法将状态栏窗口添加到Window中。mWindowManager.addView(mStatusBarWindowView, mLp);...代码省略...}
}

3、attach首先调用getBarLayoutParams方法获取状态栏类型窗口所需要的布局参数，下面是获取状态栏类型窗口所需要的布局参数的相关代码

private WindowManager.LayoutParams getBarLayoutParams(int rotation) {WindowManager.LayoutParams lp = getBarLayoutParamsForRotation(rotation);lp.paramsForRotation = new WindowManager.LayoutParams[4];for (int rot = Surface.ROTATION_0; rot <= Surface.ROTATION_270; rot++) {lp.paramsForRotation[rot] = getBarLayoutParamsForRotation(rot);}return lp;}private WindowManager.LayoutParams getBarLayoutParamsForRotation(int rotation) {int height = mBarHeight;if (INSETS_LAYOUT_GENERALIZATION) {switch (rotation) {case ROTATION_UNDEFINED:case Surface.ROTATION_0:case Surface.ROTATION_180:height = SystemBarUtils.getStatusBarHeightForRotation(mContext, Surface.ROTATION_0);break;case Surface.ROTATION_90:height = SystemBarUtils.getStatusBarHeightForRotation(mContext, Surface.ROTATION_90);break;case Surface.ROTATION_270:height = SystemBarUtils.getStatusBarHeightForRotation(mContext, Surface.ROTATION_270);break;}}WindowManager.LayoutParams lp = new WindowManager.LayoutParams(WindowManager.LayoutParams.MATCH_PARENT,//填充设备整个宽度height,//根据当前屏幕旋转角度所得到的状态栏高度WindowManager.LayoutParams.TYPE_STATUS_BAR,//指定窗口类型为状态栏WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE| WindowManager.LayoutParams.FLAG_SPLIT_TOUCH| WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS,PixelFormat.TRANSLUCENT);//窗口背景半透明lp.privateFlags |= PRIVATE_FLAG_COLOR_SPACE_AGNOSTIC;lp.token = new Binder();lp.gravity = Gravity.TOP;lp.setFitInsetsTypes(0 /* types */);lp.setTitle("StatusBar");lp.packageName = mContext.getPackageName();lp.layoutInDisplayCutoutMode = LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS;return lp;}

4、在成功获取状态栏类型窗口所需要的布局参数后，便会调用WindowManager的addView方法将状态栏视图窗口添加到Window中。

六、总结

经过前面几步，我们初步分析完了状态栏视图的创建和添加流程，最后用一张图对前面的代码流程做一个回顾。

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