Android 10 SystemUI启动流程

自己看，如果不对，请指出！

image.png

framework/base/services/java/com/android/server/SystemServer.java

public static void main(String[] args) {
        // setp 1 SystemServer启动
        new SystemServer().run();
}
private void run() {
            // step 2 这里启动很多服务，包括RuntimeService等等
            startOtherServices();
}
private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
        // step 3 AMS对象调用systemReady()，这里开始启动Launcher流程
        mActivityManagerService.systemReady(()->{
              // step 4 启动SystemUI，网络管理服务等
              // windowManagerF是WindowManagerServiced对象
              startSystemUi(context, windowManagerF);
        });
    }

    private static void startSystemUi(Context context, WindowManagerService windowManager) {
        Intent intent = new Intent();
        intent.setComponent(new ComponentName("com.android.systemui",
                "com.android.systemui.SystemUIService"));
        intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
        //Slog.d(TAG, "Starting service: " + intent);
        context.startServiceAsUser(intent, UserHandle.SYSTEM);
        // WindowManagerService回调SystemUI启动，内部是WindowManagerPolicy的回调
        windowManager.onSystemUiStarted();
    }
}

frameworks/base/packages/SystemUI/src/com/android/systemui/SystemUIAppComponentFactory.java
该类是配置在SystemUI的AndroidManifest.xml的Application中的android:appComponentFactory节点

@Override
    public Application instantiateApplication(ClassLoader cl, String className)
            throws InstantiationException, IllegalAccessException, ClassNotFoundException {
        // step 5 当SystemUIService被SystemServer启动后，SystemUI程序会先进入这个回调函数，具体原理分析ContextImpl，AppComponentFactory 
        Application app = super.instantiateApplication(cl, className);
        if (app instanceof SystemUIApplication) {
            ((SystemUIApplication) app).setContextAvailableCallback(
                    context -> {
                        // step 7 初始化SystemUIFactory
                        SystemUIFactory.createFromConfig(context);
                        SystemUIFactory.getInstance().getRootComponent().inject(
                                SystemUIAppComponentFactory.this);
                    }
            );
        }
        return app;
    }

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

public class SystemUIApplication extends Application implements SysUiServiceProvider {
    @Override
    public void onCreate() {
        super.onCreate();
        // step 6 回调通知给SystemUIAppComponentFactory
        mContextAvailableCallback.onContextAvailable(this);
    }
}

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

public class SystemUIFactory {

    public static void createFromConfig(Context context) {
        final String clsName = context.getString(R.string.config_systemUIFactoryComponent);
        try {
            Class<?> cls = null;
            cls = context.getClassLoader().loadClass(clsName);
            mFactory = (SystemUIFactory) cls.newInstance();
            // step 8 反射回去SystemUIFactory静态对象，并初始化
            mFactory.init(context);
        } catch (Throwable t) {
        }
    }

    private void init(Context context) {
        mRootComponent = buildSystemUIRootComponent(context);
        // step 9 初始化
        Dependency.initDependencies(mRootComponent);
    }
}

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

public class Dependency {

    public static void initDependencies(SystemUIRootComponent rootComponent) {
        sDependency = new Dependency();
        rootComponent.createDependency().createSystemUI(sDependency);

        // step10 加载各种管理类，在getDependency时获取对象，通过get方法初始化
        sDependency.start();
    }
}

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

public class SystemUIService extends Service {
    @Override
    public void onCreate() {
        super.onCreate();
        // step 11 通过SystemUIApplication启动对应服务
        ((SystemUIApplication) getApplication()).startServicesIfNeeded();
    }
}

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

public class SystemUIApplication extends Application implements SysUiServiceProvider {

    public void startServicesIfNeeded() {
        // 读取xml配置文件中定义的services，服务都继承于SystemUI模板
        String[] names = getResources().getStringArray(R.array.config_systemUIServiceComponents);
        // step 12
        startServicesIfNeeded(/* metricsPrefix= */ "StartServices", names);
    }

    private void startServicesIfNeeded(String metricsPrefix, String[] services) {
        // 根据xml配置初文件的服务列表，始化服务数组对象
        mServices = new SystemUI[services.length];

        final int N = services.length;
        for (int i = 0; i < N; i++) {
            String clsName = services[i];
            Class cls;
            try {
                // 反射获取服务对象
                cls = Class.forName(clsName);
                Object o = cls.newInstance();
                if (o instanceof SystemUI.Injector) {
                    o = ((SystemUI.Injector) o).apply(this);
                }
                mServices[i] = (SystemUI) o;
            } catch(ClassNotFoundException ex){
                throw new RuntimeException(ex);
            } catch (IllegalAccessException ex) {
                throw new RuntimeException(ex);
            } catch (InstantiationException ex) {
                throw new RuntimeException(ex);
            }
            mServices[i].mContext = this;
            mServices[i].mComponents = mComponents;
            // 调用各服务的start
            // step 13 其中包含SystemBar
            mServices[i].start();
            if (mBootCompleted) {
                // 调用各服务的onBootCompleted
                mServices[i].onBootCompleted();
            }
        }
}

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

    <string-array name="config_systemUIServiceComponents" translatable="false">
        <item>com.android.systemui.util.NotificationChannels</item>
        <item>com.android.systemui.statusbar.CommandQueue$CommandQueueStart</item>
        <item>com.android.systemui.keyguard.KeyguardViewMediator</item>
        <item>com.android.systemui.recents.Recents</item>
        <item>com.android.systemui.volume.VolumeUI</item>
        <item>com.android.systemui.stackdivider.Divider</item>
        <item>com.android.systemui.SystemBars</item>
        <item>com.android.systemui.usb.StorageNotification</item>
        <item>com.android.systemui.power.PowerUI</item>
        <item>com.android.systemui.media.RingtonePlayer</item>
        <item>com.android.systemui.keyboard.KeyboardUI</item>
        <item>com.android.systemui.pip.PipUI</item>
        <item>com.android.systemui.shortcut.ShortcutKeyDispatcher</item>
        <item>@string/config_systemUIVendorServiceComponent</item>
        <item>com.android.systemui.util.leak.GarbageMonitor$Service</item>
        <item>com.android.systemui.LatencyTester</item>
        <item>com.android.systemui.globalactions.GlobalActionsComponent</item>
        <item>com.android.systemui.ScreenDecorations</item>
        <item>com.android.systemui.biometrics.BiometricDialogImpl</item>
        <item>com.android.systemui.SliceBroadcastRelayHandler</item>
        <item>com.android.systemui.SizeCompatModeActivityController</item>
        <item>com.android.systemui.statusbar.notification.InstantAppNotifier</item>
        <item>com.android.systemui.theme.ThemeOverlayController</item>
    </string-array>

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

public class SystemBars extends SystemUI {

    @Override
    public void start() {
        // step 14
        createStatusBarFromConfig();
    }

    private void createStatusBarFromConfig() {
        // 获取配置文件statubar的信息
        final String clsName = mContext.getString(R.string.config_statusBarComponent);
        Class<?> cls = null;
        try {
            // 加载StatuaBar.java
            cls = mContext.getClassLoader().loadClass(clsName);
        } catch (Throwable t) {
        }
        try {
            // 反射获取mStatusBar对象
            mStatusBar = (SystemUI) cls.newInstance();
        } catch (Throwable t) {
        }
        mStatusBar.mContext = mContext;
        mStatusBar.mComponents = mComponents;
        if (mStatusBar instanceof StatusBar) {
            SystemUIFactory.getInstance().getRootComponent()
                    .getStatusBarInjector()
                    .createStatusBar((StatusBar) mStatusBar);
        }
        // step 15
        mStatusBar.start();
    }
}

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

    <string name="config_statusBarComponent" translatable="false">com.android.systemui.statusbar.phone.StatusBar</string>

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

public class StatusBar extends SystemUI implements DemoMode,
        ActivityStarter, OnUnlockMethodChangedListener,
        OnHeadsUpChangedListener, CommandQueue.Callbacks, ZenModeController.Callback,
        ColorExtractor.OnColorsChangedListener, ConfigurationListener,
        StatusBarStateController.StateListener, ShadeController,
        ActivityLaunchAnimator.Callback, AppOpsController.Callback {

    @Override
    public void start() {
        // step 16 通过Dependency获取各种控制器
        getDependencies();

        RegisterStatusBarResult result = null;
        try {
            result = mBarService.registerStatusBar(mCommandQueue);
        } catch (RemoteException ex) {
            ex.rethrowFromSystemServer();
        }
        // step 17 创建状态栏视图
        createAndAddWindows(result);
    }

    public void createAndAddWindows(@Nullable RegisterStatusBarResult result) {
        // step 18
        makeStatusBarView(result);
        mStatusBarWindowController = Dependency.get(StatusBarWindowController.class);
        mStatusBarWindowController.add(mStatusBarWindow, getStatusBarHeight());
    }

    protected void makeStatusBarView(@Nullable RegisterStatusBarResult result) {
        final Context context = mContext;
        // 更新display信息
        updateDisplaySize(); // populates mDisplayMetrics
        // 更新资源信息
        updateResources();
        // 更新主题信息
        updateTheme();

        // step 19 加载mStatusBar布局
        inflateStatusBarWindow(context);

    }

    protected void inflateStatusBarWindow(Context context) {
        mStatusBarWindow = (StatusBarWindowView) mInjectionInflater.injectable(
                LayoutInflater.from(context)).inflate(R.layout.super_status_bar, null);
    }

}