怀化网站建设哪家便宜,网站模板建站,电商网站首页代码,游戏代理免费加盟文章目录 一、CarService的基本架构1.1、Android Automative整体框架1.2、Framework CarService1.3、目录结构1.3.1、CarService1.3.2、Car APP 二、CarService的启动流程2.1、系统启动后在SystemServer进程中启动CarServiceHelperService2.2、CarService启动 三、CarService源… 文章目录 一、CarService的基本架构1.1、Android Automative整体框架1.2、Framework CarService1.3、目录结构1.3.1、CarService1.3.2、Car APP 二、CarService的启动流程2.1、系统启动后在SystemServer进程中启动CarServiceHelperService2.2、CarService启动 三、CarService源码分析3.1、CarService框架源码分析3.2、CarAudioService源码分析3.2.1、构造函数3.2.2、setupDynamicRouting3.2.3、AudioManager::registerAudioPolicy3.2.4、AudioService::registerAudioPolicy3.2.4.1、流程图3.2.4.2、AudioService::registerAudioPolicy代码3.2.4.3、AudioPolicyProxy构造函数3.2.4.4、AudioPolicyProxy::setExtVolumeController 3.2.5、CarAudioService::setupVolumeGroups3.2.5.1、这里通过CarVolumeGroupsHelper类加载car_volume_groups.xml文件3.2.5.2、packages/services/Car/service/res/xml/car_volume_groups.xml文件3.2.5.3、USAGE、ContextNumber和volumeGroups的关系 团队博客: 汽车电子社区 一、CarService的基本架构
1.1、Android Automative整体框架 从这幅图中我们可以看出Android Automative是在原先Android的系统架构上增加了一些与车相关的图中虚线框中绿色背景的模块。 1. Car App包括OEM和第三方开发的App 2. Car API内有包含 CarSensorManager 在内的 API。位于 /platform/packages/services/Car/car-lib。 3. CarService系统中与车相关的服务位于 /platform/packages/services/Car/目录。 4. 车载 HAL用于定义 OEM 可以实现的车辆属性的接口。包含属性元数据例如车辆属性是否为 int 以及允许使用哪些更改模式。位于 hardware/libhardware/include/hardware/vehicle.h。如需了解基本参考实现请参阅 hardware/libhardware/modules/vehicle/。
1.2、Framework CarService Android O/P为Automotive场景提供了一系列的服务这些服务统被称为CarService。它们与HAL层的VehicleHAL通信进而通过车载总线(例如CAN总线)与车身进行通讯同时它们还为应用层的APP提供接口从而让APP能够实现对车身的控制与状态的显示。 CarManage位于packages/services/Car/car-lib/src/android/car/hardware目录 CarService位于packages/services/Car/service/src/com/android/car目录。
1.3、目录结构
1.3.1、CarService
├── Android.mk
├── apicheck.mk
├── apicheck_msg_current.txt
├── apicheck_msg_last.txt
├── car-cluster-logging-renderer //LoggingClusterRenderingService继承InstrumentClusterRenderingService
├── car-default-input-service //按键消息处理
├── car-lib //提供给汽车App特有的接口许多定制的模块都在这里实现包括Sensor,HVAC,Cabin,ActiveParkingAssiance,Diagnostic,Vendor等
├── car-maps-placeholder //地图软件相关
├── car_product //系统编译相关
├── car-support-lib //android.support.car
├── car-systemtest-lib //系统测试相关
├── car-usb-handler //开机自启用于管理车机USB
├── CleanSpec.mk
├── evs
├── obd2-lib
├── PREUPLOAD.cfg
├── procfs-inspector
├── service //com.android.car是一个后台运行的组件可以长时间运行并且不需要和用户去交互的这里即使应用被销毁它也可以正常工作
├── tests
├── tools //是一系列的工具要提到的是里面的emulator测试需要用到的。python写的通过adb可以连接vehicleHal的工具用于模拟测试
├── TrustAgent
└── vehicle-hal-support-lib1.3.2、Car APP Car APP的相关源码位于packages/apps/Car/目录其中packages/services/Car/car_product/build/car.mk里面决定了需要编译哪些相关apksystem/priv-app。 packages/services/Car/car_product/build/car.mk内容如下
# Common make file for all car buildsPRODUCT_PUBLIC_SEPOLICY_DIRS packages/services/Car/car_product/sepolicy/public
PRODUCT_PRIVATE_SEPOLICY_DIRS packages/services/Car/car_product/sepolicy/privatePRODUCT_PACKAGES \Bluetooth \CarActivityResolver \CarDeveloperOptions \CarSettingsIntelligence \CarManagedProvisioning \OneTimeInitializer \CarProvision \StatementService \SystemUpdaterPRODUCT_PACKAGES \clatd \pppd \screenrecord# This is for testing
ifneq (,$(filter userdebug eng, $(TARGET_BUILD_VARIANT)))
PRODUCT_PACKAGES \DefaultStorageMonitoringCompanionApp \EmbeddedKitchenSinkApp \GarageModeTestApp \ExperimentalCarService \BugReportApp \NetworkPreferenceApp \SampleCustomInputService \AdasLocationTestApp \curl \# SEPolicy for test apps / services
BOARD_SEPOLICY_DIRS packages/services/Car/car_product/sepolicy/test
endif# ClusterOsDouble is the testing app to test Cluster2 framework and it can handle Cluster VHAL
# and do some Cluster OS role.
ifeq ($(ENABLE_CLUSTER_OS_DOUBLE), true)
PRODUCT_PACKAGES ClusterHomeSample ClusterOsDouble
else
# DirectRenderingCluster is the sample app for the old Cluster framework.
PRODUCT_PACKAGES DirectRenderingCluster
endif # ENABLE_CLUSTER_OS_DOUBLEPRODUCT_COPY_FILES \frameworks/av/media/libeffects/data/audio_effects.conf:system/etc/audio_effects.confPRODUCT_PROPERTY_OVERRIDES \persist.bluetooth.enablenewavrcpfalse \ro.carrierunknownPRODUCT_SYSTEM_DEFAULT_PROPERTIES \config.disable_systemtextclassifiertrue###
### Suggested values for multi-user properties - can be overridden
#### Enable headless system user mode
PRODUCT_SYSTEM_DEFAULT_PROPERTIES \ro.fw.mu.headless_system_user?true# Enable user pre-creation
PRODUCT_SYSTEM_DEFAULT_PROPERTIES \android.car.number_pre_created_users?1 \android.car.number_pre_created_guests?1# Enable User HAL integration
# NOTE: when set to true, VHAL must also implement the user-related properties,
# otherwise CarService will ignore it
PRODUCT_SYSTEM_DEFAULT_PROPERTIES \android.car.user_hal_enabled?true### end of multi-user properties #### Overlay for Google network and fused location providers
$(call inherit-product, device/sample/products/location_overlay.mk)
$(call inherit-product-if-exists, frameworks/webview/chromium/chromium.mk)
$(call inherit-product, packages/services/Car/car_product/build/car_base.mk)# Overrides
PRODUCT_BRAND : generic
PRODUCT_DEVICE : generic
PRODUCT_NAME : generic_car_no_telephonyPRODUCT_IS_AUTOMOTIVE : truePRODUCT_PROPERTY_OVERRIDES : \ro.config.ringtoneGirtab.ogg \ro.config.notification_soundTethys.ogg \ro.config.alarm_alertOxygen.ogg \$(PRODUCT_PROPERTY_OVERRIDES) \PRODUCT_PROPERTY_OVERRIDES \keyguard.no_require_simtrue# TODO(b/205189147): Remove the following change after the proper fix is landed.
# Uses the local KeyGuard animation to resolve TaskView misalignment issue after display-on.
PRODUCT_SYSTEM_PROPERTIES \persist.wm.enable_remote_keyguard_animation0# Automotive specific packages
PRODUCT_PACKAGES \CarFrameworkPackageStubs \CarService \CarShell \CarDialerApp \CarRadioApp \OverviewApp \CarSystemUI \LocalMediaPlayer \CarMediaApp \CarMessengerApp \CarHTMLViewer \CarMapsPlaceholder \CarLatinIME \CarSettings \CarUsbHandler \android.car \car-frameworks-service \com.android.car.procfsinspector \libcar-framework-service-jni \ScriptExecutor \# RROs
PRODUCT_PACKAGES \CarPermissionControllerRRO \# System Server components
# Order is important: if X depends on Y, then Y should precede X on the list.
PRODUCT_SYSTEM_SERVER_JARS car-frameworks-service
# TODO: make the order optimal by appending car-frameworks-service at the end
# after its dependency services. Currently the order is violated because this
# makefile is included before AOSP makefile.
PRODUCT_BROKEN_SUBOPTIMAL_ORDER_OF_SYSTEM_SERVER_JARS : true# Boot animation
PRODUCT_COPY_FILES \packages/services/Car/car_product/bootanimations/bootanimation-832.zip:system/media/bootanimation.zipPRODUCT_LOCALES : \en_US \af_ZA \am_ET \ar_EG ar_XB \as_IN \az_AZ \be_BY \bg_BG \bn_BD \bs_BA \ca_ES \cs_CZ \da_DK \de_DE \el_GR \en_AU en_CA en_GB en_IN en_XA \es_ES es_US \et_EE \eu_ES \fa_IR \fi_FI \fil_PH \fr_CA fr_FR \gl_ES \gu_IN \hi_IN \hr_HR \hu_HU \hy_AM \id_ID \is_IS \it_IT \iw_IL \ja_JP \ka_GE \kk_KZ \km_KH km_MH \kn_IN \ko_KR \ky_KG \lo_LA \lv_LV \lt_LT \mk_MK \ml_IN \mn_MN \mr_IN \ms_MY \my_MM \ne_NP \nl_NL \no_NO \or_IN \pa_IN \pl_PL \pt_BR pt_PT \ro_RO \ru_RU \si_LK \sk_SK \sl_SI \sq_AL \sr_RS \sv_SE \sw_TZ \ta_IN \te_IN \th_TH \tr_TR \uk_UA \ur_PK \uz_UZ \vi_VN \zh_CN zh_HK zh_TW \zu_ZAPRODUCT_BOOT_JARS \android.carPRODUCT_HIDDENAPI_STUBS : \android.car-stubs-dexPRODUCT_HIDDENAPI_STUBS_SYSTEM : \android.car-system-stubs-dexPRODUCT_HIDDENAPI_STUBS_TEST : \android.car-test-stubs-dex# Disable Prime Shader Cache in SurfaceFlinger to make it available faster
PRODUCT_PROPERTY_OVERRIDES \service.sf.prime_shader_cache0二、CarService的启动流程 2.1、系统启动后在SystemServer进程中启动CarServiceHelperService 1. 在Android系统之后系统首先会启动一个名为Zygote的进程而Zygote进程又会启动SystemServer进程这里我们先来看SystemServer的main方法。
frameworks/base/services/java/com/android/server/SystemServer.javapublic final class SystemServer implements Dumpable {public static void main(String[] args) {new SystemServer().run();}private void run(){...代码省略...// Start services.try {t.traceBegin(StartServices);startBootstrapServices(t);//启动引导服务startCoreServices(t);//启动核心服务startOtherServices(t);//启动其他服务} catch (Throwable ex) {Slog.e(System, ******************************************);Slog.e(System, ************ Failure starting system services, ex);throw ex;} finally {t.traceEnd(); // StartServices}...代码省略...}
}main方法里启动了run方法而在run方法中会调用了startOtherServices() 方法。 2. startOtherServices和CarService相关的关键代码如下所示。
public final class SystemServer implements Dumpable {private static final String CAR_SERVICE_HELPER_SERVICE_CLASS com.android.internal.car.CarServiceHelperService;private PackageManager mPackageManager;private void startOtherServices() {mActivityManagerService.systemReady(() - {...代码省略...if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTOMOTIVE)) {t.traceBegin(StartCarServiceHelperService);//如果有车机服务则开启车机帮助服务final SystemService cshs mSystemServiceManager.startService(CAR_SERVICE_HELPER_SERVICE_CLASS);if (cshs instanceof Dumpable) {mDumper.addDumpable((Dumpable) cshs);}if (cshs instanceof DevicePolicySafetyChecker) {dpms.setDevicePolicySafetyChecker((DevicePolicySafetyChecker) cshs);}t.traceEnd();}...代码省略...}}
}3. SystemServiceManager的startService方法如下所示。
frameworks/base/services/core/java/com/android/server/SystemServiceManager.javapublic class SystemServiceManager {//存储了SystemServiceManager负责启动的各种服务private final ArrayListSystemService mServices new ArrayListSystemService();public SystemService startService(String className) {final ClassSystemService serviceClass loadClassFromLoader(className,this.getClass().getClassLoader());return startService(serviceClass);}SuppressWarnings(unchecked)public T extends SystemService T startService(ClassT serviceClass) {try {final String name serviceClass.getName();...代码省略...final T service;try {ConstructorT constructor serviceClass.getConstructor(Context.class);service constructor.newInstance(mContext);} ...代码省略...startService(service);return service;} finally {Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);}}public void startService(NonNull final SystemService service) {// Register it.mServices.add(service);// Start it.long time SystemClock.elapsedRealtime();try {service.onStart();} catch (RuntimeException ex) {throw new RuntimeException(Failed to start service service.getClass().getName() : onStart threw an exception, ex);}warnIfTooLong(SystemClock.elapsedRealtime() - time, service, onStart);}
}因为前面我们传入的参数为com.android.internal.car.CarServiceHelperService所以这里startService方法首先会通过反射创建CarServiceHelperService对象实例然后将其存储在类型ArrayList的mServices中紧接着会调用CarServiceHelperService的onStart方法。 4. CarServiceHelperService的onStart方法如下所示。
frameworks/opt/car/services/src/com/android/internal/car/CarServiceHelperService.javapublic class CarServiceHelperService extends SystemServiceimplements Dumpable, DevicePolicySafetyChecker {Overridepublic void onStart() {EventLog.writeEvent(EventLogTags.CAR_HELPER_START);IntentFilter filter new IntentFilter(Intent.ACTION_REBOOT);filter.addAction(Intent.ACTION_SHUTDOWN);mContext.registerReceiverForAllUsers(mShutdownEventReceiver, filter, null, null);mCarWatchdogDaemonHelper.addOnConnectionChangeListener(mConnectionListener);mCarWatchdogDaemonHelper.connect();Intent intent new Intent();intent.setPackage(com.android.car);intent.setAction(CAR_SERVICE_INTERFACE);//通过bindService绑定车机服务CarServiceif (!mContext.bindServiceAsUser(intent, mCarServiceConnection, Context.BIND_AUTO_CREATE,mHandler, UserHandle.SYSTEM)) {Slogf.wtf(TAG, cannot start car service);}loadNativeLibrary();}void loadNativeLibrary() {System.loadLibrary(car-framework-service-jni);}
}packages/services/Car/car-lib/src/com/android/car/internal/common/CommonConstants.javapublic final class CommonConstants {// CarService Constantspublic static final String CAR_SERVICE_INTERFACE android.car.ICar;
}CarServiceHelperService的onStart方法首先创建一个Action为android.car.ICar包名为com.android.car的Intent然后通过bindService的方式启动该Intent对应的服务而这个服务正是车机模块才有的CarService服务。
2.2、CarService启动 1、系统关于CarService服务的声明如下所示。
packages/services/Car/service/AndroidManifest.xml?xml version1.0 encodingutf-8?
manifest xmlns:androidhttp://schemas.android.com/apk/res/androidxmlns:androidprvhttp://schemas.android.com/apk/prv/res/androidpackagecom.android.carcoreApptrueandroid:sharedUserIdandroid.uid.system!--...代码省略...-- application android:labelstring/app_titleandroid:directBootAwaretrueandroid:allowBackupfalseandroid:persistenttrueservice android:name.CarServiceandroid:singleUsertrueandroid:exportedtrueintent-filteraction android:nameandroid.car.ICar//intent-filter/service!--...代码省略...-- /application
/manifest 结合这个配置文件我们可以知道CarServiceHelperService最终所启动的就是CarService这个服务。 2、CarService的onCreate方法如下所示。
public class CarService extends Service {private ICarImpl mICarImpl;Overridepublic void onCreate() {...代码省略...mICarImpl new ICarImpl(this,mVehicle,SystemInterface.Builder.defaultSystemInterface(this).build(),mVehicleInterfaceName);mICarImpl.init();linkToDeath(mVehicle, mVehicleDeathRecipient);//将ICarImpl存储到系统服务管理者ServiceManager中ServiceManager.addService(car_service, mICarImpl);SystemProperties.set(boot.car_service_created, 1);super.onCreate();initTiming.traceEnd(); // CarService.onCreate}Overridepublic int onStartCommand(Intent intent, int flags, int startId) {// keep it alive.return START_STICKY;}Overridepublic IBinder onBind(Intent intent) {return mICarImpl;}
}CarService的onCreate方法会创建一个关键对象ICarImpl的实例并将该实例赋值给mICarImpl属性变量然后会调用该对象的init方法之后还会将mICarImpl存储到ServiceManager中。另外结合CarService的onBind方法我们可以知道CarServiceHelperService通过bindService方式开启CarServiceCarService会返回mICarImpl对象通过该Binder对象使二者建立双向跨进程通信。
三、CarService源码分析
3.1、CarService框架源码分析 当服务启动之后, 首先调用其onCreate方法. CarService的onCreate方法实现如下: Overridepublic void onCreate() {Log.i(CarLog.TAG_SERVICE, Service onCreate);//获取通知管理NotificationManager对象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();linkToDeath(mVehicle, mVehicleDeathRecipient);ServiceManager.addService(car_service, mICarImpl);//设置SystemProperty属性 carService已创建SystemProperties.set(boot.car_service_created, 1);super.onCreate();}主要做了两件事情: 1. 获取mVehicle 车辆相关的HIDL Binder远程对象。 2. 创建了mICarImpl对象, 并将其添加到ServiceManager管理的服务列表中. 这里的ICarImpl起着创建并管理各个服务的作用。在它的构造函数中创建了各个服务的实例,并添加到服务列表中源码如下:
packages/services/Car/service/src/com/android/car/ICarImpl.javapublic ICarImpl(Context serviceContext, IVehicle vehicle, SystemInterface systemInterface,CanBusErrorNotifier errorNotifier, String vehicleInterfaceName) {mContext serviceContext;mSystemInterface systemInterface;mHal new VehicleHal(vehicle);mVehicleInterfaceName vehicleInterfaceName;//创建各种重要的服务mUserManagerHelper new CarUserManagerHelper(serviceContext);final Resources res mContext.getResources();final int maxRunningUsers res.getInteger(com.android.internal.R.integer.config_multiuserMaxRunningUsers);mCarUserService new CarUserService(serviceContext, mUserManagerHelper,ActivityManager.getService(), maxRunningUsers);mSystemActivityMonitoringService new SystemActivityMonitoringService(serviceContext);mCarPowerManagementService new CarPowerManagementService(mContext, mHal.getPowerHal(),systemInterface, mUserManagerHelper);mCarPropertyService new CarPropertyService(serviceContext, mHal.getPropertyHal());....//将重要的服务缓存到 CarLocalServicesCarLocalServices.addService(CarPowerManagementService.class, mCarPowerManagementService);CarLocalServices.addService(CarUserService.class, mCarUserService);CarLocalServices.addService(CarTrustedDeviceService.class, mCarTrustedDeviceService);// 将创建的服务对象依次添加到一个list中保存起来ListCarServiceBase allServices new ArrayList();allServices.add(mFeatureController);allServices.add(mCarUserService);.....
}这些创建的服务就是上文介绍的汽车服务.。
3.2、CarAudioService源码分析 3.2.1、构造函数 这里读取配置文件audioUseDynamicRouting确定是否使用动态Routing。
public CarAudioService(Context context) {mContext context;mTelephonyManager (TelephonyManager) mContext.getSystemService(Context.TELEPHONY_SERVICE);mAudioManager (AudioManager) mContext.getSystemService(Context.AUDIO_SERVICE);mUseDynamicRouting mContext.getResources().getBoolean(R.bool.audioUseDynamicRouting);
}3.2.2、setupDynamicRouting 当mUseDynamicRouting为true时将调用setupDynamicRouting函数该函数里会创建一个AudioPolicy 并通过mAudioManager.registerAudioPolicy函数注册该AudioPolicy。
private void setupDynamicRouting() {final IAudioControl audioControl getAudioControl();if (audioControl null) {return;}AudioPolicy audioPolicy getDynamicAudioPolicy(audioControl);int r mAudioManager.registerAudioPolicy(audioPolicy);if (r ! AudioManager.SUCCESS) {throw new RuntimeException(registerAudioPolicy failed r);}mAudioPolicy audioPolicy;
}3.2.3、AudioManager::registerAudioPolicy
public int registerAudioPolicy(NonNull AudioPolicy policy) {if (policy null) {throw new IllegalArgumentException(Illegal null AudioPolicy argument);}final IAudioService service getService();try {String regId service.registerAudioPolicy(policy.getConfig(), policy.cb(),policy.hasFocusListener(), policy.isFocusPolicy(), policy.isVolumeController());if (regId null) {return ERROR;} else {policy.setRegistration(regId);}// successful registration} catch (RemoteException e) {throw e.rethrowFromSystemServer();}return SUCCESS;
}【1】policy.isVolumeController() 这里mVolCb 的值就是通过setAudioPolicyVolumeCallback函数设置进来的因此这里的 mVolCb 就是CarAudioService的mAudioPolicyVolumeCallback public boolean isVolumeController() { return mVolCb ! null; }
public Builder setAudioPolicyVolumeCallback(NonNull AudioPolicyVolumeCallback vc) {if (vc null) {throw new IllegalArgumentException(Invalid null volume callback);}mVolCb vc;return this;
}【2】这里的policy.cb()为IAudioPolicyCallback 这个很重要后续将会用到
public IAudioPolicyCallback cb() { return mPolicyCb; }private final IAudioPolicyCallback mPolicyCb new IAudioPolicyCallback.Stub() {public void notifyAudioFocusGrant(AudioFocusInfo afi, int requestResult) {sendMsg(MSG_FOCUS_GRANT, afi, requestResult);if (DEBUG) {Log.v(TAG, notifyAudioFocusGrant: pack afi.getPackageName() client afi.getClientId() reqRes requestResult);}}public void notifyAudioFocusLoss(AudioFocusInfo afi, boolean wasNotified) {sendMsg(MSG_FOCUS_LOSS, afi, wasNotified ? 1 : 0);if (DEBUG) {Log.v(TAG, notifyAudioFocusLoss: pack afi.getPackageName() client afi.getClientId() wasNotified wasNotified);}}public void notifyAudioFocusRequest(AudioFocusInfo afi, int requestResult) {sendMsg(MSG_FOCUS_REQUEST, afi, requestResult);if (DEBUG) {Log.v(TAG, notifyAudioFocusRequest: pack afi.getPackageName() client afi.getClientId() gen afi.getGen());}}public void notifyAudioFocusAbandon(AudioFocusInfo afi) {sendMsg(MSG_FOCUS_ABANDON, afi, 0 /* ignored */);if (DEBUG) {Log.v(TAG, notifyAudioFocusAbandon: pack afi.getPackageName() client afi.getClientId());}}public void notifyMixStateUpdate(String regId, int state) {for (AudioMix mix : mConfig.getMixes()) {if (mix.getRegistration().equals(regId)) {mix.mMixState state;sendMsg(MSG_MIX_STATE_UPDATE, mix, 0/*ignored*/);if (DEBUG) {Log.v(TAG, notifyMixStateUpdate: regId regId state state);}}}}public void notifyVolumeAdjust(int adjustment) {sendMsg(MSG_VOL_ADJUST, null /* ignored */, adjustment);if (DEBUG) {Log.v(TAG, notifyVolumeAdjust: adjustment);}}};3.2.4、AudioService::registerAudioPolicy
3.2.4.1、流程图 3.2.4.2、AudioService::registerAudioPolicy代码 AudioPolicyProxy app new AudioPolicyProxy(policyConfig, pcb, hasFocusListener, isFocusPolicy, isVolumeController); 这里实例化了AudioPolicyProxy并将registerAudioPolicy参数作为AudioPolicyProxy构造函数的参数。如上所述isVolumeController的值就是policy.isVolumeController()因此为true。 public String registerAudioPolicy(AudioPolicyConfig policyConfig, IAudioPolicyCallback pcb,boolean hasFocusListener, boolean isFocusPolicy, boolean isVolumeController) {AudioSystem.setDynamicPolicyCallback(mDynPolicyCallback);String regId null;// error handlingboolean hasPermissionForPolicy (PackageManager.PERMISSION_GRANTED mContext.checkCallingPermission(android.Manifest.permission.MODIFY_AUDIO_ROUTING));if (!hasPermissionForPolicy) {Slog.w(TAG, Cant register audio policy for pid Binder.getCallingPid() / uid Binder.getCallingUid() , need MODIFY_AUDIO_ROUTING);return null;}mDynPolicyLogger.log((new AudioEventLogger.StringEvent(registerAudioPolicy for pcb.asBinder() with config: policyConfig)).printLog(TAG));synchronized (mAudioPolicies) {try {if (mAudioPolicies.containsKey(pcb.asBinder())) {Slog.e(TAG, Cannot re-register policy);return null;}AudioPolicyProxy app new AudioPolicyProxy(policyConfig, pcb, hasFocusListener,isFocusPolicy, isVolumeController);pcb.asBinder().linkToDeath(app, 0/*flags*/);regId app.getRegistrationId();mAudioPolicies.put(pcb.asBinder(), app);} catch (RemoteException e) {// audio policy owner has already died!Slog.w(TAG, Audio policy registration failed, could not link to pcb binder death, e);return null;}}return regId;
}3.2.4.3、AudioPolicyProxy构造函数
AudioPolicyProxy(AudioPolicyConfig config, IAudioPolicyCallback token,boolean hasFocusListener, boolean isFocusPolicy, boolean isVolumeController) {super(config);setRegistration(new String(config.hashCode() :ap: mAudioPolicyCounter));mPolicyCallback token;mHasFocusListener hasFocusListener;mIsVolumeController isVolumeController;if (mHasFocusListener) {mMediaFocusControl.addFocusFollower(mPolicyCallback);// can only ever be true if there is a focus listenerif (isFocusPolicy) {mIsFocusPolicy true;mMediaFocusControl.setFocusPolicy(mPolicyCallback);}}if (mIsVolumeController) {setExtVolumeController(mPolicyCallback);}connectMixes();
}3.2.4.4、AudioPolicyProxy::setExtVolumeController 这里设置mExtVolumeController 的值为类AudioPolicy中的IAudioPolicyCallback mPolicyCb。
private void setExtVolumeController(IAudioPolicyCallback apc) {if (!mContext.getResources().getBoolean(com.android.internal.R.bool.config_handleVolumeKeysInWindowManager)) {Log.e(TAG, Cannot set external volume controller: device not set for volume keys handled in PhoneWindowManager);return;}synchronized (mExtVolumeControllerLock) {if (mExtVolumeController ! null !mExtVolumeController.asBinder().pingBinder()) {Log.e(TAG, Cannot set external volume controller: existing controller);}mExtVolumeController apc;}
}3.2.5、CarAudioService::setupVolumeGroups
3.2.5.1、这里通过CarVolumeGroupsHelper类加载car_volume_groups.xml文件 private void setupVolumeGroups() {Preconditions.checkArgument(mCarAudioDeviceInfos.size() 0,No bus device is configured to setup volume groups);final CarVolumeGroupsHelper helper new CarVolumeGroupsHelper(mContext, R.xml.car_volume_groups);mCarVolumeGroups helper.loadVolumeGroups();for (CarVolumeGroup group : mCarVolumeGroups) {for (int contextNumber : group.getContexts()) {int busNumber mContextToBus.get(contextNumber);group.bind(contextNumber, busNumber, mCarAudioDeviceInfos.get(busNumber));}// Now that we have all our contexts, ensure the HAL gets our intial valuegroup.setCurrentGainIndex(group.getCurrentGainIndex());Log.v(CarLog.TAG_AUDIO, Processed volume group: group);}// Perform validation after all volume groups are processedif (!validateVolumeGroups()) {throw new RuntimeException(Invalid volume groups configuration);}
}3.2.5.2、packages/services/Car/service/res/xml/car_volume_groups.xml文件
volumeGroups xmlns:carhttp://schemas.android.com/apk/res-autogroupcontext car:contextmusic/context car:contextcall_ring/context car:contextnotification/context car:contextsystem_sound//groupgroupcontext car:contextnavigation/context car:contextvoice_command//groupgroupcontext car:contextcall//groupgroupcontext car:contextalarm//group
/volumeGroups3.2.5.3、USAGE、ContextNumber和volumeGroups的关系
