Android Automotive（二）—— CarService

CarService介绍

【1】CarService 继承Service

public class CarService extends Service

【2】CarService 的onCreate函数

  @Override
    public void onCreate() {
        Log.i(CarLog.TAG_SERVICE, "Service onCreate");
        mCanBusErrorNotifier = new CanBusErrorNotifier(this /* context */);
        mVehicle = getVehicle();

        if (mVehicle == null) {
            throw new IllegalStateException("Vehicle HAL service is not available.");
        }
        try {
            mVehicleInterfaceName = mVehicle.interfaceDescriptor();
        } catch (RemoteException e) {
            throw new IllegalStateException("Unable to get Vehicle HAL interface descriptor", e);
        }

        Log.i(CarLog.TAG_SERVICE, "Connected to " + mVehicleInterfaceName);

        mICarImpl = new ICarImpl(this,
                mVehicle,
                SystemInterface.Builder.defaultSystemInterface(this).build(),
                mCanBusErrorNotifier,
                mVehicleInterfaceName);
        mICarImpl.init();
        SystemProperties.set("boot.car_service_created", "1");

        linkToDeath(mVehicle, mVehicleDeathRecipient);

        ServiceManager.addService("car_service", mICarImpl);
        super.onCreate();
    }

【3】在onCreate函数中getVehicle()返回一个hardare的接口

    private static IVehicle getVehicle() {
        try {
            return android.hardware.automotive.vehicle.V2_0.IVehicle.getService();
        } catch (RemoteException e) {
            Log.e(CarLog.TAG_SERVICE, "Failed to get IVehicle service", e);
        } catch (NoSuchElementException e) {
            Log.e(CarLog.TAG_SERVICE, "IVehicle service not registered yet");
        }
        return null;
    }

【4】在onCreate函数中实例化ICarImpl，并调用init函数

        mICarImpl = new ICarImpl(this,
                mVehicle,
                SystemInterface.Builder.defaultSystemInterface(this).build(),
                mCanBusErrorNotifier,
                mVehicleInterfaceName);
        mICarImpl.init();

【5】ICarImpl构造函数里实例化了VehicleHal和Service，并将这些Service加入到list中

public ICarImpl(Context serviceContext, IVehicle vehicle, SystemInterface systemInterface,
            CanBusErrorNotifier errorNotifier, String vehicleInterfaceName) {
        mContext = serviceContext;
        mSystemInterface = systemInterface;
        mHal = new VehicleHal(vehicle);
        mVehicleInterfaceName = vehicleInterfaceName;
        mSystemActivityMonitoringService = new SystemActivityMonitoringService(serviceContext);
        mCarPowerManagementService = new CarPowerManagementService(mContext, mHal.getPowerHal(),
                systemInterface);
        mCarPropertyService = new CarPropertyService(serviceContext, mHal.getPropertyHal());
        mCarDrivingStateService = new CarDrivingStateService(serviceContext, mCarPropertyService);
        mCarUXRestrictionsService = new CarUxRestrictionsManagerService(serviceContext,
                mCarDrivingStateService, mCarPropertyService);
        mCarPackageManagerService = new CarPackageManagerService(serviceContext,
                mCarUXRestrictionsService,
                mSystemActivityMonitoringService);
        mCarInputService = new CarInputService(serviceContext, mHal.getInputHal());
        mCarProjectionService = new CarProjectionService(serviceContext, mCarInputService);
        mGarageModeService = new GarageModeService(mContext, mCarPowerManagementService);
        mCarLocationService = new CarLocationService(mContext, mCarPowerManagementService,
                mCarPropertyService);
        mAppFocusService = new AppFocusService(serviceContext, mSystemActivityMonitoringService);
        mCarAudioService = new CarAudioService(serviceContext);
        mCarNightService = new CarNightService(serviceContext, mCarPropertyService);
        mInstrumentClusterService = new InstrumentClusterService(serviceContext,
                mAppFocusService, mCarInputService);
        mSystemStateControllerService = new SystemStateControllerService(serviceContext,
                mCarPowerManagementService, mCarAudioService, this);
        mPerUserCarServiceHelper = new PerUserCarServiceHelper(serviceContext);
        mCarBluetoothService = new CarBluetoothService(serviceContext, mCarPropertyService,
                mPerUserCarServiceHelper, mCarUXRestrictionsService);
        mVmsSubscriberService = new VmsSubscriberService(serviceContext, mHal.getVmsHal());
        mVmsPublisherService = new VmsPublisherService(serviceContext, mHal.getVmsHal());
        mCarDiagnosticService = new CarDiagnosticService(serviceContext, mHal.getDiagnosticHal());
        mCarStorageMonitoringService = new CarStorageMonitoringService(serviceContext,
                systemInterface);
        mCarConfigurationService =
                new CarConfigurationService(serviceContext, new JsonReaderImpl());
        mUserManagerHelper = new CarUserManagerHelper(serviceContext);

        // Be careful with order. Service depending on other service should be inited later.
        List allServices = new ArrayList<>();
        allServices.add(mSystemActivityMonitoringService);
        allServices.add(mCarPowerManagementService);
        allServices.add(mCarPropertyService);
        allServices.add(mCarDrivingStateService);
        allServices.add(mCarUXRestrictionsService);
        allServices.add(mCarPackageManagerService);
        allServices.add(mCarInputService);
        allServices.add(mCarLocationService);
        allServices.add(mGarageModeService);
        allServices.add(mAppFocusService);
        allServices.add(mCarAudioService);
        allServices.add(mCarNightService);
        allServices.add(mInstrumentClusterService);
        allServices.add(mCarProjectionService);
        allServices.add(mSystemStateControllerService);
        allServices.add(mCarBluetoothService);
        allServices.add(mCarDiagnosticService);
        allServices.add(mPerUserCarServiceHelper);
        allServices.add(mCarStorageMonitoringService);
        allServices.add(mCarConfigurationService);
        allServices.add(mVmsSubscriberService);
        allServices.add(mVmsPublisherService);

        if (mUserManagerHelper.isHeadlessSystemUser()) {
            mCarUserService = new CarUserService(serviceContext, mUserManagerHelper);
            allServices.add(mCarUserService);
        }

        mAllServices = allServices.toArray(new CarServiceBase[allServices.size()]);
    }

【6】ICarImpl的init函数

遍历service list，调用其init函数

    @MainThread
    void init() {
        traceBegin("VehicleHal.init");
        mHal.init();
        traceEnd();
        traceBegin("CarService.initAllServices");
        for (CarServiceBase service : mAllServices) {
            service.init();
        }
        traceEnd();
    }

下面将介绍每个具体的service。

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2.  SystemInterface

2.1 类图

2.2 流程图

2.3 说明

SystemInterface作为一个容器，封装和实现了DisplayInterface, IOInterface, StorageMonitoringInterface, SystemStateInterface, TimeInterface, WakeLockInterface六个接口，

并统一提供对外的接口。

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3.  VehicleHal

 * Abstraction for vehicle HAL. This class handles interface with native HAL and do basic parsing
 * of received data (type check). Then each event is sent to corresponding {@link HalServiceBase}
 * implementation. It is responsibility of {@link HalServiceBase} to convert data to corresponding
 * Car*Service for Car*Manager API.

3.1 流程图

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4.  SystemActivityMonitoringService

Service to monitor AMS for new Activity or Service launching.

4.1 类图

4.2  代码

【1】调用IActivityManager方法：

      mAm.registerProcessObserver(mProcessObserver);
      mAm.registerTaskStackListener(mTaskListener);

    public SystemActivityMonitoringService(Context context) {
        mContext = context;
        mMonitorHandlerThread = new HandlerThread(CarLog.TAG_AM);
        mMonitorHandlerThread.start();
        mHandler = new ActivityMonitorHandler(mMonitorHandlerThread.getLooper());
        mProcessObserver = new ProcessObserver();
        mTaskListener = new TaskListener();
        mAm = ActivityManager.getService();
        // Monitoring both listeners are necessary as there are cases where one listener cannot
        // monitor activity change.
        try {
            mAm.registerProcessObserver(mProcessObserver);
            mAm.registerTaskStackListener(mTaskListener);
        } catch (RemoteException e) {
            Log.e(CarLog.TAG_AM, "cannot register activity monitoring", e);
            throw new RuntimeException(e);
        }
        updateTasks();
    }

【2】 提供接口ActivityLaunchListener供外部使用

    public interface ActivityLaunchListener {
        /**
         * Notify launch of activity.
         * @param topTask Task information for what is currently launched.
         */
        void onActivityLaunch(TopTaskInfoContainer topTask);
    }

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5. PropertyHalService和CarPropertyService

5.1 PropertyHalService

流程图可以参考上面 “VehicleHal” 的流程

5.2 PropertyHalServiceIds构造函数

这里创建一个数组mProps，然后存储所有的属性和权限

public class PropertyHalServiceIds {
    // Index (key is propertyId, and the value is readPermission, writePermission
    private final SparseArray> mProps;

    public PropertyHalServiceIds() {
        mProps = new SparseArray<>();

        // Add propertyId and read/write permissions
        // Cabin Properties
        mProps.put(VehicleProperty.DOOR_POS, new Pair<>(
                Car.PERMISSION_CONTROL_CAR_DOORS,
                Car.PERMISSION_CONTROL_CAR_DOORS));
        mProps.put(VehicleProperty.DOOR_MOVE, new Pair<>(
                Car.PERMISSION_CONTROL_CAR_DOORS,
                Car.PERMISSION_CONTROL_CAR_DOORS));
            ......

    }
}

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6. CarPackageManagerService

6.1 CarPackageManagerService构造函数

这里读取ActivityBlocking配置：

      mEnableActivityBlocking = res.getBoolean(R.bool.enableActivityBlockingForSafety);
      String blockingActivity = res.getString(R.string.activityBlockingActivity);

    public CarPackageManagerService(Context context,
            CarUxRestrictionsManagerService uxRestrictionsService,
            SystemActivityMonitoringService systemActivityMonitoringService) {
        mContext = context;
        mCarUxRestrictionsService = uxRestrictionsService;
        mSystemActivityMonitoringService = systemActivityMonitoringService;
        mPackageManager = mContext.getPackageManager();
        mUxRestrictionsListener = new UxRestrictionsListener(uxRestrictionsService);
        mHandlerThread = new HandlerThread(CarLog.TAG_PACKAGE);
        mHandlerThread.start();
        mHandler = new PackageHandler(mHandlerThread.getLooper());
        Resources res = context.getResources();
        mEnableActivityBlocking = res.getBoolean(R.bool.enableActivityBlockingForSafety);
        String blockingActivity = res.getString(R.string.activityBlockingActivity);
        mActivityBlockingActivity = ComponentName.unflattenFromString(blockingActivity);
    }

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