SystemUIApplication#startServicesIfNeeded()
定义在: config.xml
/frameworks/base/packages/SystemUI/res
<string-array name="config_systemUIServiceComponents" translatable="false">
<item>com.android.systemui.util.NotificationChannels</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.statusbar.phone.StatusBar</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.AuthController</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>
<item>com.android.systemui.accessibility.WindowMagnification</item>
<item>com.android.systemui.accessibility.SystemActions</item>
<item>com.android.systemui.toast.ToastUI</item>
</string-array>
这些服务继承了SystemUI ,会调用 start方法 。