android10 CarService
图 CarService架构
Android Automotive OS定义了标准的硬件抽象层(HAL)来规范各个子系统与Framework的调用接口，并且通过CarService及其相关的Car API对上层应用提供标准编程接口。通过这张图可以看出CarService运行在独立的进程中，其作为原有Android服务的补充。
CarService的启动流程
CarService 时序图
xref: /frameworks/base/services/java/com/android/server/SystemServer.java
265 private static final String CAR_SERVICE_HELPER_SERVICE_CLASS =
266 "com.android.internal.car.CarServiceHelperService";
..........
2066 if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTOMOTIVE)) {
2067 traceBeginAndSlog("StartCarServiceHelperService");
2068 mSystemServiceManager.startService(CAR_SERVICE_HELPER_SERVICE_CLASS);
2069 traceEnd();
2070 }
通过SystemServiceManager开启服务并传人参数CAR_SERVICE_HELPER_SERVICE_CLASS。
xref: /frameworks/base/services/core/java/com/android/server/SystemServiceManager.java
78 /**
79 * Creates and starts a system service. The class must be a subclass of
80 * {@link com.android.server.SystemService}.
81 *
82 * @param serviceClass A Java class that implements the SystemService interface.
83 * @return The service instance, never null.
84 * @throws RuntimeException if the service fails to start.
85 */
86 @SuppressWarnings("unchecked")
87 public T startService(Class serviceClass) {
88 try {
89 final String name = serviceClass.getName();
90 Slog.i(TAG, "Starting " + name);
91 Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartService " + name);
92
93 // Create the service.
94 if (!SystemService.class.isAssignableFrom(serviceClass)) {
95 throw new RuntimeException("Failed to create " + name
96 + ": service must extend " + SystemService.class.getName());
97 }
98 final T service;
99 try {
100 Constructor constructor = serviceClass.getConstructor(Context.class);
101 service = constructor.newInstance(mContext);
102 } catch (InstantiationException ex) {
103 throw new RuntimeException("Failed to create service " + name
104 + ": service could not be instantiated", ex);
105 } catch (IllegalAccessException ex) {
106 throw new RuntimeException("Failed to create service " + name
107 + ": service must have a public constructor with a Context argument", ex);
108 } catch (NoSuchMethodException ex) {
109 throw new RuntimeException("Failed to create service " + name
110 + ": service must have a public constructor with a Context argument", ex);
111 } catch (InvocationTargetException ex) {
112 throw new RuntimeException("Failed to create service " + name
113 + ": service constructor threw an exception", ex);
114 }
115
116 startService(service);
117 return service;
118 } finally {
119 Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
120 }
121 }
122
123 public void startService(@NonNull final SystemService service) {
124 // Register it.
125 mServices.add(service);
126 // Start it.
127 long time = SystemClock.elapsedRealtime();
128 try {
129 service.onStart();
130 } catch (RuntimeException ex) {
131 throw new RuntimeException("Failed to start service " + service.getClass().getName()
132 + ": onStart threw an exception", ex);
133 }
134 warnIfTooLong(SystemClock.elapsedRealtime() - time, service, "onStart");
135 } SystemServiceManager会通过反射创建CarServiceHelperService对象，并调用其onStart方法。
xref: /frameworks/opt/car/services/src/com/android/internal/car/CarServiceHelperService.java
63 private static final String CAR_SERVICE_INTERFACE = "android.car.ICar";
...........
142 @Override
143 public void onStart() {
144 Intent intent = new Intent();
145 intent.setPackage("com.android.car");
146 intent.setAction(CAR_SERVICE_INTERFACE);
147 if (!getContext().bindServiceAsUser(intent, mCarServiceConnection, Context.BIND_AUTO_CREATE,
148 UserHandle.SYSTEM)) {
149 Slog.wtf(TAG, "cannot start car service");
150 }
151 System.loadLibrary("car-framework-service-jni");
152 }
xref: /packages/services/Car/service/AndroidManifest.xml
507
509
510
512 在CarServiceHelperService的onStart方法中，通过intent设置action然后绑定服务就创建了CarService进程。
xref: /packages/services/Car/service/src/com/android/car/CarService.java
72 @Override
73 public void onCreate() {
74 Log.i(CarLog.TAG_SERVICE, "Service onCreate");
75 mCanBusErrorNotifier = new CanBusErrorNotifier(this /* context */);
76 mVehicle = getVehicle();
77
78 if (mVehicle == null) {
79 throw new IllegalStateException("Vehicle HAL service is not available.");
80 }
81 try {
82 mVehicleInterfaceName = mVehicle.interfaceDescriptor();
83 } catch (RemoteException e) {
84 throw new IllegalStateException("Unable to get Vehicle HAL interface descriptor", e);
85 }
86
87 Log.i(CarLog.TAG_SERVICE, "Connected to " + mVehicleInterfaceName);
88
89 mICarImpl = new ICarImpl(this,
90 mVehicle,
91 SystemInterface.Builder.defaultSystemInterface(this).build(),
92 mCanBusErrorNotifier,
93 mVehicleInterfaceName);
94 mICarImpl.init();
95
96 linkToDeath(mVehicle, mVehicleDeathRecipient);
97
98 ServiceManager.addService("car_service", mICarImpl);
99 SystemProperties.set("boot.car_service_created", "1");
100 super.onCreate();
101 }创建mVehicle、mICarImpl对象，并将mICarImpl添加到ServiceManager中。
xref: /packages/services/Car/service/src/com/android/car/ICarImpl.java
117 public ICarImpl(Context serviceContext, IVehicle vehicle, SystemInterface systemInterface,
118 CanBusErrorNotifier errorNotifier, String vehicleInterfaceName) {
119 mContext = serviceContext;
120 mSystemInterface = systemInterface;
121 mHal = new VehicleHal(vehicle);
122 mVehicleInterfaceName = vehicleInterfaceName;
123 mUserManagerHelper = new CarUserManagerHelper(serviceContext);
124 final Resources res = mContext.getResources();
125 final int maxRunningUsers = res.getInteger(
126 com.android.internal.R.integer.config_multiuserMaxRunningUsers);
127 mCarUserService = new CarUserService(serviceContext, mUserManagerHelper,
128 ActivityManager.getService(), maxRunningUsers);
129 mSystemActivityMonitoringService = new SystemActivityMonitoringService(serviceContext);
130 mCarPowerManagementService = new CarPowerManagementService(mContext, mHal.getPowerHal(),
131 systemInterface, mUserManagerHelper);
132 mCarPropertyService = new CarPropertyService(serviceContext, mHal.getPropertyHal());
133 mCarDrivingStateService = new CarDrivingStateService(serviceContext, mCarPropertyService);
134 mCarUXRestrictionsService = new CarUxRestrictionsManagerService(serviceContext,
135 mCarDrivingStateService, mCarPropertyService);
136 mCarPackageManagerService = new CarPackageManagerService(serviceContext,
137 mCarUXRestrictionsService,
138 mSystemActivityMonitoringService,
139 mUserManagerHelper);
140 mPerUserCarServiceHelper = new PerUserCarServiceHelper(serviceContext);
141 mCarBluetoothService = new CarBluetoothService(serviceContext, mPerUserCarServiceHelper);
142 mCarInputService = new CarInputService(serviceContext, mHal.getInputHal());
143 mCarProjectionService = new CarProjectionService(
144 serviceContext, null /* handler */, mCarInputService, mCarBluetoothService);
145 mGarageModeService = new GarageModeService(mContext);
146 mAppFocusService = new AppFocusService(serviceContext, mSystemActivityMonitoringService);
147 mCarAudioService = new CarAudioService(serviceContext);
148 mCarNightService = new CarNightService(serviceContext, mCarPropertyService);
149 mInstrumentClusterService = new InstrumentClusterService(serviceContext,
150 mAppFocusService, mCarInputService);
151 mSystemStateControllerService = new SystemStateControllerService(
152 serviceContext, mCarAudioService, this);
153 mVmsBrokerService = new VmsBrokerService(mContext.getPackageManager());
154 mVmsClientManager = new VmsClientManager(
155 serviceContext, mCarUserService, mUserManagerHelper, mHal.getVmsHal());
156 mVmsSubscriberService = new VmsSubscriberService(
157 serviceContext, mVmsBrokerService, mHal.getVmsHal());
158 mVmsPublisherService = new VmsPublisherService(
159 serviceContext, mVmsBrokerService, mVmsClientManager);
160 mCarDiagnosticService = new CarDiagnosticService(serviceContext, mHal.getDiagnosticHal());
161 mCarStorageMonitoringService = new CarStorageMonitoringService(serviceContext,
162 systemInterface);
163 mCarConfigurationService =
164 new CarConfigurationService(serviceContext, new JsonReaderImpl());
165 mCarLocationService = new CarLocationService(mContext, mUserManagerHelper);
166 mCarTrustedDeviceService = new CarTrustedDeviceService(serviceContext);
167 mCarMediaService = new CarMediaService(serviceContext);
168 mCarBugreportManagerService = new CarBugreportManagerService(serviceContext);
169
170 CarLocalServices.addService(CarPowerManagementService.class, mCarPowerManagementService);
171 CarLocalServices.addService(CarUserService.class, mCarUserService);
172 CarLocalServices.addService(CarTrustedDeviceService.class, mCarTrustedDeviceService);
173 CarLocalServices.addService(SystemInterface.class, mSystemInterface);
174 CarLocalServices.addService(CarDrivingStateService.class, mCarDrivingStateService);
175 CarLocalServices.addService(PerUserCarServiceHelper.class, mPerUserCarServiceHelper);
176
177 // Be careful with order. Service depending on other service should be inited later.
178 List allServices = new ArrayList<>();
179 allServices.add(mCarUserService);
180 allServices.add(mSystemActivityMonitoringService);
181 allServices.add(mCarPowerManagementService);
182 allServices.add(mCarPropertyService);
183 allServices.add(mCarDrivingStateService);
184 allServices.add(mCarUXRestrictionsService);
185 allServices.add(mCarPackageManagerService);
186 allServices.add(mCarInputService);
187 allServices.add(mGarageModeService);
188 allServices.add(mAppFocusService);
189 allServices.add(mCarAudioService);
190 allServices.add(mCarNightService);
191 allServices.add(mInstrumentClusterService);
192 allServices.add(mSystemStateControllerService);
193 allServices.add(mPerUserCarServiceHelper);
194 allServices.add(mCarBluetoothService);
195 allServices.add(mCarProjectionService);
196 allServices.add(mCarDiagnosticService);
197 allServices.add(mCarStorageMonitoringService);
198 allServices.add(mCarConfigurationService);
199 allServices.add(mVmsClientManager);
200 allServices.add(mVmsSubscriberService);
201 allServices.add(mVmsPublisherService);
202 allServices.add(mCarTrustedDeviceService);
203 allServices.add(mCarMediaService);
204 allServices.add(mCarLocationService);
205 allServices.add(mCarBugreportManagerService);
206 mAllServices = allServices.toArray(new CarServiceBase[allServices.size()]);
207 } 在ICarImpl里面创建各种服务并添加到allServices中。
Car API的使用方式
Car carClient = Car.createCar(context);
CarHvacManager manager = (CarHvacManager) carClient.getCarManager(Car.HVAC_SERVICE);