Android TV Input Framework(TIF)--构建TV input list

这部分主要介绍tvinput是怎么来的，源码目录：frameworks/base/services/core/java/com/android/server/tv

TvInputManagerService治理着体系的种种输进，TV Input首要分为三品种型：hardware input:首要包括TV内建的种种输进端心，比方tuner、component, composite, hdmi。非hdmi

TvInputManagerService管理着系统的各种输入，TV Input主要分为三种类型：

hardware input:主要包含TV内建的各种输入端口，比如tuner、component, composite, hdmi。
非hardware input: 视频点播等非内建的硬件端口属于这种类型。
HDMI logic input:带有HDMI CEC的设备属于这种类型。

TvInputManagerService由systemServer创建，我们先看看它的构造方法

  public TvInputManagerService(Context context) {super(context);...mTvInputHardwareManager = new TvInputHardwareManager(context, new HardwareListener());synchronized (mLock) {mUserStates.put(mCurrentUserId, new UserState(mContext, mCurrentUserId));}}

在构造方法中会创建一下TvInputHardwareManager实例，并传入一个HardwareListener实例给TvInputHardwareManager。TvInputHardwareManager通过TvInputHal来获取TV硬件输入的各种状态，并通过HardwareListener通知TvInputManagerService。

class TvInputHardwareManager implements TvInputHal.Callbackpublic interface Callback {public void onDeviceAvailable(TvInputHardwareInfo info, TvStreamConfig[] configs);public void onDeviceUnavailable(int deviceId);public void onStreamConfigurationChanged(int deviceId, TvStreamConfig[] configs);public void onFirstFrameCaptured(int deviceId, int streamId);}public TvInputHardwareManager(Context context, Listener listener) {mContext = context;mListener = listener;...mHal.init();}

TvInputHardwareManager实现了TvInputHal.Callback接口，在构造方法中调用mHal.init()对TvInputHal进行初始化，在TvInputHal初始化过程中，所有TV内建的Input都会通过onDeviceAvailable通知给TvInputHardWareManager,我们看一下onDeviceAvailable的实现：

  public void onDeviceAvailable(TvInputHardwareInfo info, TvStreamConfig[] configs) {synchronized (mLock) {...buildHardwareListLocked();mHandler.obtainmessage(ListenerHandler.HARDWARE_DEVICE_ADDED, 0, 0, info).sendToTarget();...}}}

onDeviceAvailable会调用buildHardwareListLocked把Tv Input的信息放入一个链表，TV Input的信息用TvInputHardwareInfo类表示，

private void buildHardwareListLocked() {mHardwareList.clear();for (int i = 0; i < mConnections.size(); ++i) {mHardwareList.add(mConnections.valueAt(i).getHardwareInfoLocked());}}

然后通过mHandler.obtainMessage(ListenerHandler.HARDWARE_DEVICE_ADDED, 0, 0, info).sendToTarget()发送到handler线程处理，

 public final void handleMessage(Message msg) {switch (msg.what) {...case HARDWARE_DEVICE_ADDED: {TvInputHardwareInfo info = (TvInputHardwareInfo) msg.obj;mListener.onHardwareDeviceAdded(info);break;}...

还记得TvInputManagerService在创建TvInputHardwareManager的时候传入的HardwareListener吗？它就是mListener, HardwareListener的onHardwareDeviceAdded会被调用，

public void onHardwareDeviceAdded(TvInputHardwareInfo info) {synchronized (mLock) {UserState userState = getUserStateLocked(mCurrentUserId);// Broadcast the event to all hardware inputs.for (ServiceState serviceState : userState.serviceStateMap.values()) {if (!serviceState.isHardware || serviceState.service == null) continue;try {serviceState.service.notifyHardwareAdded(info);} catch (RemoteException e) {Slog.e(TAG, "error in notifyHardwareAdded", e);}}}}

到目前为止，我们只是对TvInputManagerService的构造方法进行分析，userState.serviceStateMap还是空的，所以这个时候onHardwareDeviceAdded被调用其实什么事情都没有做。

我们接着分析TvInputManagerService的初始化过程，

 public void onBootPhase(int phase) {if (phase == SystemService.PHASE_SYSTEM_SERVICES_READY) {registerBroadcastReceivers();} else if (phase == SystemService.PHASE_THIRD_PARTY_APPS_CAN_START) {synchronized (mLock) {buildTvInputListLocked(mCurrentUserId, null);buildTvContentRatingSystemListLocked(mCurrentUserId);}}mTvInputHardwareManager.onBootPhase(phase);}

当第三方的app可以启动的时候，即phase == SystemService.PHASE_THIRD_PARTY_APPS_CAN_START，调用buildTvInputListLocked开始构建Tv Input List。

    private void buildTvInputListLocked(int userId, String[] updatedpackages) {UserState userState = getUserStateLocked(userId);userState.packageSet.clear();if (DEBUG) Slog.d(TAG, "buildTvInputList");PackageManager pm = mContext.getPackageManager();List<ResolveInfo> services = pm.queryIntentServices(new Intent(TvInputService.SERVICE_INTERFACE),PackageManager.GET_SERVICES | PackageManager.GET_META_DATA);                       ---<1>List<TvInputInfo> inputList = new ArrayList<TvInputInfo>();for (ResolveInfo ri : services) {ServiceInfo si = ri.serviceInfo;if (!android.Manifest.permission.BIND_TV_INPUT.equals(si.permission)) {Slog.w(TAG, "Skipping TV input " + si.name + ": it does not require the permission "+ android.Manifest.permission.BIND_TV_INPUT);continue;}ComponentName component = new ComponentName(si.packageName, si.name);if (hasHardwarePermission(pm, component)) {ServiceState serviceState = userState.serviceStateMap.get(component);if (serviceState == null) {// We see this hardware TV input service for the first time; we need to// prepare the ServiceState object so that we can connect to the service and// let it add TvInputInfo objects to mInputList if there's any.serviceState = new ServiceState(component, userId);                     ---<2>userState.serviceStateMap.put(component, serviceState);updateServiceConnectionLocked(component, userId);    ---<3>} else {inputList.addAll(serviceState.inputList);            ---<4>}} else {try {inputList.add(TvInputInfo.createTvInputInfo(mContext, ri));---<5>} catch (XmlPullParserException | IOException e) {Slog.e(TAG, "failed to load TV input " + si.name, e);continue;}}userState.packageSet.add(si.packageName);}Map<String, TvInputState> inputMap = new HashMap<String, TvInputState>();             ---<6>for (TvInputInfo info : inputList) {if (DEBUG) {Slog.d(TAG, "add " + info.getId());}TvInputState state = userState.inputMap.get(info.getId());if (state == null) {state = new TvInputState();     }state.info = info;inputMap.put(info.getId(), state);       }for (String inputId : inputMap.keySet()) {if (!userState.inputMap.containsKey(inputId)) {              ---<7>notifyInputAddedLocked(userState, inputId);} else if (updatedPackages != null) {// Notify the package updatesComponentName component = inputMap.get(inputId).info.getComponent();for (String updatedPackage : updatedPackages) {if (component.getPackageName().equals(updatedPackage)) {updateServiceConnectionLocked(component, userId);notifyInputUpdatedLocked(userState, inputId);break;}}}}for (String inputId : userState.inputMap.keySet()) {if (!inputMap.containsKey(inputId)) {    ---<8>TvInputInfo info = userState.inputMap.get(inputId).info;ServiceState serviceState = userState.serviceStateMap.get(info.getComponent());if (serviceState != null) {abortPendingCreateSessionRequestsLocked(serviceState, inputId, userId);}notifyInputRemovedLocked(userState, inputId);}}userState.inputMap.clear();userState.inputMap = inputMap;               ---<9>}

这个方法比较长,关键行标上了序号,下面逐一解释:

查找所有的package中的service,如果package的service在AndroidManifest.xml中声明了如下属性：

android:permission="android.permission.BIND_TV_INPUT"

那么就认为这个service代表一种Tv Input，这些service都继承自TvInputService。对于TV内建的输入端口，还要在package的AndroidManifest.xml声明

<uses-permission android:name="android.permission.TV_INPUT_HARDWARE" />
<service android:name="com.montage.tvinput.dvb.DvbTvInputService"
android:enabled="true"
 android:permission="android.permission.BIND_TV_INPUT"
android:protectionLevel="signatureOrSystem"
android:exported="true">
<intent-filter>
<action android:name="android.media.tv.TvInputService" />
</intent-filter>
<meta-data android:name="android.media.tv.input"
android:resource="@xml/dvbc_tv_input" />
</service>
/*******************************/
TvInputService
{
public static final String SERVICE_INTERFACE = "android.media.tv.TvInputService";
public static final String SERVICE_META_DATA = "android.media.tv.input";
}

对于内建的硬件输入端口，TvInputManangerService会创建对应的ServiceState实例，并跟对应的Service建立连接，

  private ServiceState(ComponentName component, int userId) {this.component = component;this.connection = new InputServiceConnection(component, userId);this.isHardware = hasHardwarePermission(mContext.getPackageManager(), component);}

注意this.connection = new InputServiceConnection(component, userId)，稍后会用到。

 private void updateServiceConnectionLocked(ComponentName component, int userId) {...Intent i = new Intent(TvInputService.SERVICE_INTERFACE).setComponent(component);serviceState.bound = mContext.bindServiceAsUser(i, serviceState.connection, Context.BIND_AUTO_CREATE, new UserHandle(userId));...}

3.在updateServiceConnectionLocked中通过Intent跟service建立连接，这个时候inputList是空的，buildTvInputListLocked继续执行返回。当跟service连接成功以后，serviceState.connection.onServiceConnected会被回调，就是前面说的InputServiceConnection.onServiceConnected。

public void onServiceConnected(ComponentName component, IBinder service) {...// Register a callback, if we need to.if (serviceState.isHardware && serviceState.callback == null) {serviceState.callback = new ServiceCallback(mComponent, mUserId);try {serviceState.service.registerCallback(serviceState.callback);} catch (RemoteException e) {Slog.e(TAG, "error in registerCallback", e);}}...if (serviceState.isHardware) {List<TvInputHardwareInfo> hardwareInfoList =mTvInputHardwareManager.getHardwareList();for (TvInputHardwareInfo hardwareInfo : hardwareInfoList) {try {serviceState.service.notifyHardwareAdded(hardwareInfo);} catch (RemoteException e) {Slog.e(TAG, "error in notifyHardwareAdded", e);}}List<HdmiDeviceInfo> deviceInfoList =mTvInputHardwareManager.getHdmiDeviceList();for (HdmiDeviceInfo deviceInfo : deviceInfoList) {try {serviceState.service.notifyHdmiDeviceAdded(deviceInfo);} catch (RemoteException e) {Slog.e(TAG, "error in notifyHdmiDeviceAdded", e);}}}}}

接着会向Service注册callback,后面会用到。然后通过mTvInputHardwareManager.getHardwareList获取之前初始化的时候保存的Hardware list，调用service的notifyHardwareAdded方法，我们看一下TvInputService的notifyHardwareAdded实现：

public void notifyHardwareAdded(TvInputHardwareInfo hardwareInfo) {mServiceHandler.obtainMessage(ServiceHandler.DO_ADD_HARDWARE_TV_INPUT,hardwareInfo).sendToTarget();}

通知Handler线程DO_ADD_HARDWARE_TV_INPUT，

public final void handleMessage(Message msg) {switch (msg.what) {...case DO_ADD_HARDWARE_TV_INPUT: {TvInputHardwareInfo hardwareInfo = (TvInputHardwareInfo) msg.obj;TvInputInfo inputInfo = onHardwareAdded(hardwareInfo);if (inputInfo != null) {broadcastAddHardwareTvInput(hardwareInfo.getDeviceId(), inputInfo);}return;}...

然后service的onHardwareAdded方法被调用，并返回TvInputInfo，这代表一个TV Input，然后通过broadcastAddHardwareTvInput通知TvInputManagerService,

 private void broadcastAddHardwareTvInput(int deviceId, TvInputInfo inputInfo) {int n = mCallbacks.beginBroadcast();for (int i = 0; i < n; ++i) {try {mCallbacks.getBroadcastItem(i).addHardwareTvInput(deviceId, inputInfo);} catch (RemoteException e) {Log.e(TAG, "Error while broadcasting.", e);}}mCallbacks.finishBroadcast();}

我们在跟service建立连接以后，注册了callback，callback的addHardwareTvInput被调用，我们看一下TvInputManagerService中addHardwareTvInput的实现,

 private void addTvInputLocked(TvInputInfo inputInfo) {ServiceState serviceState = getServiceStateLocked(mComponent, mUserId);serviceState.inputList.add(inputInfo);buildTvInputListLocked(mUserId, null);}@Overridepublic void addHardwareTvInput(int deviceId, TvInputInfo inputInfo) {ensureHardwarePermission();ensureValidInput(inputInfo);synchronized (mLock) {mTvInputHardwareManager.addHardwareTvInput(deviceId, inputInfo);addTvInputLocked(inputInfo);}}

addHardwareTvInput会调用addTvInputLocked，addTvInputLocked把TvInputInfo存入serviceState.inputList，接着调用buildTvInputListLocked重新构建Tv input list。

4.再次调用buildTvInputListLocked的时候，serviceState不为null，把serviceState.inputList放入到inputList。
5. 如果不是TV内建的硬件Input,直接创建TvInputInfo并放入InputList。
6. 每一个Tv Input都对应一个TvInputState，通过inputId在inputMap中索引。
7. 如果新构建的inputMap中的inputId在userState.inputMap中没有，表明这个TV input是新增加的，如果TV app有注册callback，那么TV app的onInputAdded会被调用。
8. 如果userState.inputMap中的inputId在新构建的inputMap中没有，表明这个TV Input被移除，如果TV app有注册callback，那么TV app的onInputRemoved会被调用。
9. userState.inputMap被新构建的inputMap替换，至此TV input list构建完成。

备注：在原文章的基础上会对某些地方进行补充和扩展。

原文章：http://www.07net01.com/program/2016/02/1276341.html;

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