蓝牙之十二-HFP app层

在android6中，HFP的app层代码位于：

/packages/apps/Bluetooth/src/com/android/bluetooth/hfpclient

配置使能代码位于

    <bool name="profile_supported_hs_hfp">truebool>
    <bool name="profile_supported_hfpclient">truebool>

如上，配置了hs和hfpclinent使能，由于代码会调用层次结构比较深，这里以广度优先法分析HFP功能。
首先和HFP client息息相关的有三个文件。

HeadsetClientHalConstants.java 
HeadsetClientService.java  
HeadsetClientStateMachine.java

HeadsetClientHalConstants.java

这个文件的命名就显示其和HAL层是有关系的，里面的常量定义是和HAL层一致的。

final public class HeadsetClientHalConstants {
    // 如果这里的定义有变化，需要和HAL bt_hf_client.h保持一致
    // 0~4和bt_hf_client.h文件里定义的枚举类型是一致的，用于表示连接的断开，正在连接，连接成功，SLC（Service Level Connection）连接，和正在断开连接
    final static int CONNECTION_STATE_DISCONNECTED = 0;
    final static int CONNECTION_STATE_CONNECTING = 1;
    final static int CONNECTION_STATE_CONNECTED = 2;
    final static int CONNECTION_STATE_SLC_CONNECTED = 3;
    final static int CONNECTION_STATE_DISCONNECTING = 4;

    // 和bt_hf_client.h文件 bthf_client_audio_state_t 定义的枚举保持一致，用于指示audio状态
    final static int AUDIO_STATE_DISCONNECTED = 0;
    final static int AUDIO_STATE_CONNECTING = 1;
    final static int AUDIO_STATE_CONNECTED = 2;
    final static int AUDIO_STATE_CONNECTED_MSBC = 3;

    // 和 bt_hf_client.h的bthf_client_vr_state_t定义的枚举类型一致，VR是voice Recognition的缩写。
    final static int VR_STATE_STOPPED = 0;
    final static int VR_STATE_STARTED = 1;

    //bt_hf_client.h定义的bthf_client_volume_type_t枚举音量调节对象，speaker还是mic。
    final static int VOLUME_TYPE_SPK = 0;
    final static int VOLUME_TYPE_MIC = 1;

    // match up with bthf_client_network_state_t enum of bt_hf_client.h
    final static int NETWORK_STATE_NOT_AVAILABLE = 0;
    final static int NETWORK_STATE_AVAILABLE = 1;

    // match up with bthf_client_service_type_t enum of bt_hf_client.h
    final static int SERVICE_TYPE_HOME = 0;
    final static int SERVICE_TYPE_ROAMING = 1;

    // match up with bthf_client_call_state_t enum of bt_hf_client.h，RESP是response的缩写
    final static int CALL_STATE_ACTIVE = 0;
    final static int CALL_STATE_HELD = 1;
    final static int CALL_STATE_DIALING = 2;
    final static int CALL_STATE_ALERTING = 3;
    final static int CALL_STATE_INCOMING = 4;
    final static int CALL_STATE_WAITING = 5;
    final static int CALL_STATE_HELD_BY_RESP_HOLD = 6;

    // match up with bthf_client_call_t enum of bt_hf_client.h
    final static int CALL_NO_CALLS_IN_PROGRESS = 0;
    final static int CALL_CALLS_IN_PROGRESS = 1;

    // match up with bthf_client_callsetup_t enum of bt_hf_client.h
    final static int CALLSETUP_NONE = 0;
    final static int CALLSETUP_INCOMING = 1;
    final static int CALLSETUP_OUTGOING = 2;
    final static int CALLSETUP_ALERTING = 3;

    // match up with bthf_client_callheld_t enum of bt_hf_client.h
    final static int CALLHELD_NONE = 0;
    final static int CALLHELD_HOLD_AND_ACTIVE = 1;
    final static int CALLHELD_HOLD = 2;

    // match up with btrh_client_resp_and_hold_t of bt_hf_client.h
    final static int RESP_AND_HOLD_HELD = 0;
    final static int RESP_AND_HOLD_ACCEPT = 1;
    final static int RESP_AND_HOLD_REJECT = 2;

    // match up with bthf_client_call_direction_t enum of bt_hf_client.h
    final static int CALL_DIRECTION_OUTGOING = 0;
    final static int CALL_DIRECTION_INCOMING = 1;

    // match up with bthf_client_call_mpty_type_t enum of bt_hf_client.h，SINGLE单电话， MULTI多方电话
    final static int CALL_MPTY_TYPE_SINGLE = 0;
    final static int CALL_MPTY_TYPE_MULTI = 1;

    // match up with bthf_client_cmd_complete_t enum of bt_hf_client.h，命令完成应答
    final static int CMD_COMPLETE_OK = 0;
    final static int CMD_COMPLETE_ERROR = 1;
    final static int CMD_COMPLETE_ERROR_NO_CARRIER = 2;
    final static int CMD_COMPLETE_ERROR_BUSY = 3;
    final static int CMD_COMPLETE_ERROR_NO_ANSWER = 4;
    final static int CMD_COMPLETE_ERROR_DELAYED = 5;
    final static int CMD_COMPLETE_ERROR_BLACKLISTED = 6;
    final static int CMD_COMPLETE_ERROR_CME = 7;

    // match up with bthf_client_call_action_t enum of bt_hf_client.h，呼叫动作
    final static int CALL_ACTION_CHLD_0 = 0;
    final static int CALL_ACTION_CHLD_1 = 1;
    final static int CALL_ACTION_CHLD_2 = 2;
    final static int CALL_ACTION_CHLD_3 = 3;
    final static int CALL_ACTION_CHLD_4 = 4;
    final static int CALL_ACTION_CHLD_1x = 5;
    final static int CALL_ACTION_CHLD_2x = 6;
    final static int CALL_ACTION_ATA = 7;
    final static int CALL_ACTION_CHUP = 8;
    final static int CALL_ACTION_BTRH_0 = 9;
    final static int CALL_ACTION_BTRH_1 = 10;
    final static int CALL_ACTION_BTRH_2 = 11;

    // match up with bthf_client_subscriber_service_type_t enum of
    // bt_hf_client.h
    final static int SUBSCRIBER_SERVICE_TYPE_UNKNOWN = 0;
    final static int SUBSCRIBER_SERVICE_TYPE_VOICE = 1;
    final static int SUBSCRIBER_SERVICE_TYPE_FAX = 2;

    // match up with bthf_client_in_band_ring_state_t enum in bt_hf_client.h，电话铃声同传
    final static int IN_BAND_RING_NOT_PROVIDED = 0;
    final static int IN_BAND_RING_PROVIDED = 1;

    // AG(Audio Gate) features masks，
    // match up with masks in bt_hf_client.h
    // Three-way calling
    final static int PEER_FEAT_3WAY     = 0x00000001;
    // Echo cancellation and/or noise reduction
    final static int PEER_FEAT_ECNR     = 0x00000002;
    // Voice recognition
    final static int PEER_FEAT_VREC     = 0x00000004;
    // In-band ring tone
    final static int PEER_FEAT_INBAND   = 0x00000008;
    // Attach a phone number to a voice tag
    final static int PEER_FEAT_VTAG     = 0x00000010;
    // Ability to reject incoming call
    final static int PEER_FEAT_REJECT   = 0x00000020;
    // Enhanced Call Status
    final static int PEER_FEAT_ECS      = 0x00000040;
    // Enhanced Call Control
    final static int PEER_FEAT_ECC      = 0x00000080;
    // Extended error codes
    final static int PEER_FEAT_EXTERR   = 0x00000100;
    // Codec Negotiation
    final static int PEER_FEAT_CODEC    = 0x00000200;

    // AG's 3WC features masks
    // match up with masks in bt_hf_client.h
    // 0  Release waiting call or held calls
    final static int CHLD_FEAT_REL           = 0x00000001;
    // 1  Release active calls and accept other (waiting or held) cal
    final static int CHLD_FEAT_REL_ACC       = 0x00000002;
    // 1x Release specified active call only
    final static int CHLD_FEAT_REL_X         = 0x00000004;
    // 2  Active calls on hold and accept other (waiting or held) call
    final static int CHLD_FEAT_HOLD_ACC      = 0x00000008;
    // 2x Request private mode with specified call (put the rest on hold)
    final static int CHLD_FEAT_PRIV_X        = 0x00000010;
    // 3  Add held call to multiparty */
    final static int CHLD_FEAT_MERGE         = 0x00000020;
    // 4  Connect two calls and leave (disconnect from) multiparty */
    final static int CHLD_FEAT_MERGE_DETACH  = 0x00000040;

    // AT Commands
    // These Commands values must match with Constants defined in
    // tBTA_HF_CLIENT_AT_CMD_TYPE in bta_hf_client_api.h
    // used for sending vendor specific AT cmds to AG.

    final static int HANDSFREECLIENT_AT_CMD_NREC = 15;

    // Flag to check for local NREC support
    final static boolean HANDSFREECLIENT_NREC_SUPPORTED = true;
}

HeadsetClientService.java

public class HeadsetClientService extends ProfileService {
    //状态机，多例
    private HeadsetClientStateMachine mStateMachine;
    //Headset client服务端，单例，可以有多个HeadsetClient代理
    private static HeadsetClientService sHeadsetClientService;
    @Override，//代理的binder
    public IProfileServiceBinder initBinder() {
        return new BluetoothHeadsetClientBinder(this);
    }

        @Override
    protected boolean start() {
        mStateMachine = HeadsetClientStateMachine.make(this);//创建状态机
        IntentFilter filter = new IntentFilter(AudioManager.VOLUME_CHANGED_ACTION);
        filter.addAction(BluetoothDevice.ACTION_CONNECTION_ACCESS_REPLY);
        try {
        //注册广播时间的过滤器和行为
            registerReceiver(mBroadcastReceiver, filter);
        } catch (Exception e) {
            Log.w(TAG, "Unable to register broadcat receiver", e);
        }
        //启动服务时，service存在检查
        setHeadsetClientService(this);
        return true;
    }
    //broadcastReceiver类创建，该类向HeadsetClientStateMachine发送音量设置消息
        private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();

            if (action.equals(AudioManager.VOLUME_CHANGED_ACTION)) {
                int streamType = intent.getIntExtra(AudioManager.EXTRA_VOLUME_STREAM_TYPE, -1);
                if (streamType == AudioManager.STREAM_BLUETOOTH_SCO) {
                    int streamValue = intent
                            .getIntExtra(AudioManager.EXTRA_VOLUME_STREAM_VALUE, -1);
                    int streamPrevValue = intent.getIntExtra(
                            AudioManager.EXTRA_PREV_VOLUME_STREAM_VALUE, -1);

                    if (streamValue != -1 && streamValue != streamPrevValue) {
                        mStateMachine.sendMessage(mStateMachine.obtainMessage(
                                HeadsetClientStateMachine.SET_SPEAKER_VOLUME, streamValue, 0));
                    }
                }
            }
        }
    };
    //frameworks/base/core/java/android/bluetooth/IBluetoothHeadsetClient.aidl定义的client可以使用的接口实现。这些接口就是调用该service实现该方法的。

    private static class BluetoothHeadsetClientBinder extends IBluetoothHeadsetClient.Stub
            implements IProfileServiceBinder {
        private HeadsetClientService mService;
        ...
       }
//发送消息给state machine。实现连接功能
    public boolean connect(BluetoothDevice device) {
        enforceCallingOrSelfPermission(BLUETOOTH_ADMIN_PERM,
                "Need BLUETOOTH ADMIN permission");

        if (getPriority(device) == BluetoothProfile.PRIORITY_OFF) {
            return false;
        }

        int connectionState = mStateMachine.getConnectionState(device);
        if (connectionState == BluetoothProfile.STATE_CONNECTED ||
                connectionState == BluetoothProfile.STATE_CONNECTING) {
            return false;
        }

        mStateMachine.sendMessage(HeadsetClientStateMachine.CONNECT, device);
        return true;
    }

总结一下，该文件实现了aidl文件的方法，这些方法包括连接，连接音频，拨打/接听/拒接等，这些方法的调用是通过JNI的。这些方法的实现通过发送消息给状态机来完成。

HeadsetClientStateMachine.java

final class HeadsetClientStateMachine extends StateMachine {
//定义了四个状态机，分别是未连接，正在连接/连接成功和音频打开四个状态。
    private final Disconnected mDisconnected;
    private final Connecting mConnecting;
    private final Connected mConnected;
    private final AudioOn mAudioOn;

//块静态方法
    static {
        classInitNative();
    }