SystemServer启动SystemUI

SystemServer启动SystemUI：

    private static void startSystemUi(Context context, WindowManagerService windowManager) {
        PackageManagerInternal pm = LocalServices.getService(PackageManagerInternal.class);
        Intent intent = new Intent();
        intent.setComponent(pm.getSystemUiServiceComponent());
        intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING);
        //Slog.d(TAG, "Starting service: " + intent);
        context.startServiceAsUser(intent, UserHandle.SYSTEM);
        windowManager.onSystemUiStarted();
    }

PackageManagerInternal：

        @Override
        public ComponentName getSystemUiServiceComponent() {
            return ComponentName.unflattenFromString(mContext.getResources().getString(
                    com.android.internal.R.string.config_systemUIServiceComponent));
        }

res/res/values/config.xml：

<string name="config_systemUIServiceComponent" translatable="false">com.android.systemui/com.android.systemui.SystemUIService</string>

SystemUIService的关键代码：

 <service android:name="SystemUIService"
            android:exported="true"
        />

    @Override
    public void onCreate() {
        super.onCreate();

        // Start all of SystemUI
        ((SystemUIApplication) getApplication()).startServicesIfNeeded();
.....
}

然后会通过反射来创建配置里面的组件：

<!-- SystemUI Services: The classes of the stuff to start. -->
<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 module继承了SystemUI 类 。