Android Bluetooth源码分析总结 - framework部分

Android Bluetooth源码分析总结 - framework部分

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本篇主要包括如下内容：
1. 源码目录
2. 类图
3. use case举例

• 蓝牙服务初始化
• 打开蓝牙流程
• 搜索蓝牙流程

4. 应用层开发总结

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1，BT framework代码主要位于如下目录：

android/frameworks/base/core/java/android/bluetooth
android/frameworks/base/services/core/java/com/android/server/BluetoothManagerService.java
android/packages/apps/Bluetooth

2，class diagram如下图所示：

主要类设计意图说明如下（摘录源码）：

• BluetoothAdapter 

/**
 * Represents the local device Bluetooth adapter. The BluetoothAdapter
 * lets you perform fundamental Bluetooth tasks, such as initiate
 * device discovery, query a list of bonded (paired) devices,
 * instantiate a BluetoothDevice using a known MAC address, and create
 * a BluetoothServerSocket to listen for connection requests from other
 * devices, and start a scan for Bluetooth LE devices.
 *
 * To get a BluetoothAdapter representing the local Bluetooth
 * adapter, when running on JELLY_BEAN_MR1 and below, call the
 * static getDefaultAdapter method; when running on JELLY_BEAN_MR2 and
 * higher, retrieve it through
 * android.content.Context#getSystemService with
 * android.content.Context#BLUETOOTH_SERVICE.
 * Fundamentally, this is your starting point for all
 * Bluetooth actions. Once you have the local adapter, you can get a set of
 * BluetoothDevice objects representing all paired devices with
 * getBondedDevices(); start device discovery with
 * startDiscovery(); or create a BluetoothServerSocket to
 * listen for incoming connection requests with
 * listenUsingRfcommWithServiceRecord(String,UUID); or start a scan for
 * Bluetooth LE devices with startLeScan(LeScanCallback callback).
 *
 * Note:
 * Most methods require the android.Manifest.permission#BLUETOOTH
 * permission and some also require the
 * android.Manifest.permission#BLUETOOTH_ADMIN permission.
 *
 */
public final class BluetoothAdapter {
        ......
}

• BluetoothManagerService

class BluetoothManagerService extends IBluetoothManager.Stub {
        ......
}

/**
 * System private API for talking with the Bluetooth service.
 *
 * {@hide}
 */
interface IBluetoothManager
{
    IBluetooth registerAdapter(in IBluetoothManagerCallback callback);
    void unregisterAdapter(in IBluetoothManagerCallback callback);
    void registerStateChangeCallback(in IBluetoothStateChangeCallback callback);
    void unregisterStateChangeCallback(in IBluetoothStateChangeCallback callback);
    boolean isEnabled();
    boolean enable();
    boolean enableNoAutoConnect();
    boolean disable(boolean persist);
    IBluetoothGatt getBluetoothGatt();

    boolean bindBluetoothProfileService(int profile, IBluetoothProfileServiceConnection proxy);
    void unbindBluetoothProfileService(int profile, IBluetoothProfileServiceConnection proxy);

    String getAddress();
    String getName();

    boolean isBleScanAlwaysAvailable();
    int updateBleAppCount(IBinder b, boolean enable);
    boolean isBleAppPresent();
}

• IBluetooth

/**
 * System private API for talking with the Bluetooth service.
 *
 * {@hide}
 */
interface IBluetooth
{
    boolean isEnabled();
    int getState();
    boolean enable();
    boolean enableNoAutoConnect();
    boolean disable();

    String getAddress();
    ParcelUuid[] getUuids();
    boolean setName(in String name);
    String getName();

    int getScanMode();
    boolean setScanMode(int mode, int duration);

    int getDiscoverableTimeout();
    boolean setDiscoverableTimeout(int timeout);

    boolean startDiscovery();
    boolean cancelDiscovery();
    boolean isDiscovering();

    int getAdapterConnectionState();
    int getProfileConnectionState(int profile);

    BluetoothDevice[] getBondedDevices();
    boolean createBond(in BluetoothDevice device, in int transport);
    boolean cancelBondProcess(in BluetoothDevice device);
    boolean removeBond(in BluetoothDevice device);
    int getBondState(in BluetoothDevice device);
    int getConnectionState(in BluetoothDevice device);

 String getRemoteName(in BluetoothDevice device);
    int getRemoteType(in BluetoothDevice device);
    String getRemoteAlias(in BluetoothDevice device);
    boolean setRemoteAlias(in BluetoothDevice device, in String name);
    int getRemoteClass(in BluetoothDevice device);
    ParcelUuid[] getRemoteUuids(in BluetoothDevice device);
    boolean fetchRemoteUuids(in BluetoothDevice device);
    boolean sdpSearch(in BluetoothDevice device, in ParcelUuid uuid);

    boolean setPin(in BluetoothDevice device, boolean accept, int len, in byte[] pinCode);
    boolean setPasskey(in BluetoothDevice device, boolean accept, int len, in byte[]
    passkey);
    boolean setPairingConfirmation(in BluetoothDevice device, boolean accept);

    int getPhonebookAccessPermission(in BluetoothDevice device);
    boolean setPhonebookAccessPermission(in BluetoothDevice device, int value);
    int getMessageAccessPermission(in BluetoothDevice device);
    boolean setMessageAccessPermission(in BluetoothDevice device, int value);
    int getSimAccessPermission(in BluetoothDevice device);
    boolean setSimAccessPermission(in BluetoothDevice device, int value);

    void sendConnectionStateChange(in BluetoothDevice device, int profile, int state, int prevState);

    void registerCallback(in IBluetoothCallback callback);
    void unregisterCallback(in IBluetoothCallback callback);

    // For Socket
    ParcelFileDescriptor connectSocket(in BluetoothDevice device, int type, in ParcelUuid uuid, int port, int flag);
    ParcelFileDescriptor createSocketChannel(int type, in String serviceName, in ParcelUuid uuid, int port, int flag);

    boolean configHciSnoopLog(boolean enable);
    boolean factoryReset();

    boolean isMultiAdvertisementSupported();
    boolean isPeripheralModeSupported();
    boolean isOffloadedFilteringSupported();
    boolean isOffloadedScanBatchingSupported();
    boolean isActivityAndEnergyReportingSupported();
    void getActivityEnergyInfoFromController();
    BluetoothActivityEnergyInfo reportActivityInfo();

    // For dumpsys support
    void dump(in ParcelFileDescriptor fd);
    void onLeServiceUp();
    void onBrEdrDown();
}

另外，IBluetooth的server端实现为AdapterService的内部类（位于android/packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java），摘录如下：

    /**
     * Handlers for incoming service calls
     */
    private AdapterServiceBinder mBinder;

    /**
     * The Binder implementation must be declared to be a static class, with
     * the AdapterService instance passed in the constructor. Furthermore,
     * when the AdapterService shuts down, the reference to the AdapterService
     * must be explicitly removed.
     *
     * Otherwise, a memory leak can occur from repeated starting/stopping the
     * service...Please refer to android.os.Binder for further details on
     * why an inner instance class should be avoided.
     *
     */
    private static class AdapterServiceBinder extends IBluetooth.Stub {
                ......
    }

• BluetoothLeScanner

/**
 * This class provides methods to perform scan related operations for Bluetooth LE devices. An
 * application can scan for a particular type of Bluetooth LE devices using {@link ScanFilter}. It
 * can also request different types of callbacks for delivering the result.
 * 

 * Use {@link BluetoothAdapter#getBluetoothLeScanner()} to get an instance of
 * {@link BluetoothLeScanner}.
 * 

 * Note: Most of the scan methods here require
 * {@link android.Manifest.permission#BLUETOOTH_ADMIN} permission.
 *
 * @see ScanFilter
 */
public final class BluetoothLeScanner {
        ......
}

• BluetoothLeAdvertiser

/**
 * This class provides a way to perform Bluetooth LE advertise operations, such as starting and
 * stopping advertising. An advertiser can broadcast up to 31 bytes of advertisement data
 * represented by {@link AdvertiseData}.
 * 

 * To get an instance of {@link BluetoothLeAdvertiser}, call the
 * {@link BluetoothAdapter#getBluetoothLeAdvertiser()} method.
 * 

 * Note: Most of the methods here require {@link android.Manifest.permission#BLUETOOTH_ADMIN}
 * permission.
 *
 * @see AdvertiseData
 */
public final class BluetoothLeAdvertiser {
        ......
}

• BluetoothProfile

/**
 * Public APIs for the Bluetooth Profiles.
 *
 * 
 Clients should call {@link BluetoothAdapter#getProfileProxy},
 * to get the Profile Proxy. Each public profile implements this
 * interface.
 */
public interface BluetoothProfile {
        ......
}

可以发现有一系列的应用层profile类存在，比如BluetoothA2dp，BluetoothA2dpSink、BluetoothGatt，BluetoothHeadset，BluetoothSap，BluetoothPan等等，上述图中没有罗列完全，而且这些类都继承自BluetoothProfile. （若是有新的profile添加，可以参考已存在profile进行相关实现。）另外，每个具体的profile类（比如BluetoothA2dp）都依赖于对应的service实现（对应于BluetoothA2dpService），而这些XXXProfileService就会依赖JNI，最终调用到HAL层。

3，序列图

3.1 蓝牙服务初始化

3.2 蓝牙打开流程

• BluetoothEnabler->LocalBluetoothAdapter->BluetoothAdapter->BluetoothManagerService->IBluetooth.stub->AdapterService

各代码路径：

android/packages/apps/Settings/src/com/android/settings/bluetooth/BluetoothEnabler.java
android/frameworks/base/packages/SettingsLib/src/com/android/settingslib/bluetooth/LocalBluetoothAdapter.java
android/frameworks/base/core/java/android/bluetooth/BluetoothAdapter.java
android/frameworks/base/services/core/java/com/android/server/BluetoothManagerService.java
android/frameworks/base/core/java/android/bluetooth/IBluetooth.aidl
android/packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java

• AdapterService->AdapterState->AdapterService->JNI->bluetooth.h

各代码路径及类说明：

android/packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java
android/packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterState.java
android/hardware/libhardware/include/hardware/bluetooth.h

/**
 * This state machine handles Bluetooth Adapter State.
 * States:
 *      {@link OnState} : Bluetooth is on at this state
 *      {@link OffState}: Bluetooth is off at this state. This is the initial
 *      state.
 *      {@link PendingCommandState} : An enable / disable operation is pending.
 * TODO(BT): Add per process on state.
 */

final class AdapterState extends StateMachine {
        ......
}

/**
 * The Bluetooth Hardware Module ID
 */

#define BT_HARDWARE_MODULE_ID "bluetooth"
#define BT_STACK_MODULE_ID "bluetooth"
#define BT_STACK_TEST_MODULE_ID "bluetooth_test"


/* Bluetooth profile interface IDs */

#define BT_PROFILE_HANDSFREE_ID "handsfree"
#define BT_PROFILE_HANDSFREE_CLIENT_ID "handsfree_client"
#define BT_PROFILE_ADVANCED_AUDIO_ID "a2dp"
#define BT_PROFILE_ADVANCED_AUDIO_SINK_ID "a2dp_sink"
#define BT_PROFILE_HEALTH_ID "health"
#define BT_PROFILE_SOCKETS_ID "socket"
#define BT_PROFILE_HIDHOST_ID "hidhost"
#define BT_PROFILE_PAN_ID "pan"
#define BT_PROFILE_MAP_CLIENT_ID "map_client"
#define BT_PROFILE_SDP_CLIENT_ID "sdp"
#define BT_PROFILE_GATT_ID "gatt"
#define BT_PROFILE_AV_RC_ID "avrcp"
#define BT_PROFILE_AV_RC_CTRL_ID "avrcp_ctrl"

......
......
/** NOTE: By default, no profiles are initialized at the time of init/enable.
 *  Whenever the application invokes the 'init' API of a profile, then one of
 *  the following shall occur:
 *
 *    1.) If Bluetooth is not enabled, then the Bluetooth core shall mark the
 *        profile as enabled. Subsequently, when the application invokes the
 *        Bluetooth 'enable', as part of the enable sequence the profile that were
 *        marked shall be enabled by calling appropriate stack APIs. The
 *        'adapter_properties_cb' shall return the list of UUIDs of the
 *        enabled profiles.
 *
 *    2.) If Bluetooth is enabled, then the Bluetooth core shall invoke the stack
 *        profile API to initialize the profile and trigger a
 *        'adapter_properties_cb' with the current list of UUIDs including the
 *        newly added profile's UUID.
 *
 *   The reverse shall occur whenever the profile 'cleanup' APIs are invoked
 */

/** Represents the standard Bluetooth DM interface. */
typedef struct {
    /** set to sizeof(bt_interface_t) */
    size_t size;
    /**
     * Opens the interface and provides the callback routines
     * to the implemenation of this interface.
     */
    int (*init)(bt_callbacks_t* callbacks );

    /** Enable Bluetooth. */
    int (*enable)(void);

    /** Disable Bluetooth. */
    int (*disable)(void);

    /** Closes the interface. */
    void (*cleanup)(void);

    /** Get all Bluetooth Adapter properties at init */
    int (*get_adapter_properties)(void);

    /** Get Bluetooth Adapter property of 'type' */
    int (*get_adapter_property)(bt_property_type_t type);

    /** Set Bluetooth Adapter property of 'type' */
    /* Based on the type, val shall be one of
     * bt_bdaddr_t or bt_bdname_t or bt_scanmode_t etc
     */
    int (*set_adapter_property)(const bt_property_t *property);

    /** Get all Remote Device properties */
    int (*get_remote_device_properties)(bt_bdaddr_t *remote_addr);

    /** Get Remote Device property of 'type' */
    int (*get_remote_device_property)(bt_bdaddr_t *remote_addr,
                                      bt_property_type_t type);

    /** Set Remote Device property of 'type' */
    int (*set_remote_device_property)(bt_bdaddr_t *remote_addr,
                                      const bt_property_t *property);

    /** Get Remote Device's service record  for the given UUID */
    int (*get_remote_service_record)(bt_bdaddr_t *remote_addr,
                                     bt_uuid_t *uuid);

    /** Start SDP to get remote services */
    int (*get_remote_services)(bt_bdaddr_t *remote_addr);

    /** Start Discovery */
    int (*start_discovery)(void);

    /** Cancel Discovery */
    int (*cancel_discovery)(void);

    /** Create Bluetooth Bonding */
    int (*create_bond)(const bt_bdaddr_t *bd_addr, int transport);

    /** Remove Bond */
    int (*remove_bond)(const bt_bdaddr_t *bd_addr);

    /** Cancel Bond */
    int (*cancel_bond)(const bt_bdaddr_t *bd_addr);

    /**
     * Get the connection status for a given remote device.
     * return value of 0 means the device is not connected,
     * non-zero return status indicates an active connection.
     */
    int (*get_connection_state)(const bt_bdaddr_t *bd_addr);

    /** BT Legacy PinKey Reply */
    /** If accept==FALSE, then pin_len and pin_code shall be 0x0 */
    int (*pin_reply)(const bt_bdaddr_t *bd_addr, uint8_t accept,
                     uint8_t pin_len, bt_pin_code_t *pin_code);

    /** BT SSP Reply - Just Works, Numeric Comparison and Passkey
     * passkey shall be zero for BT_SSP_VARIANT_PASSKEY_COMPARISON &
     * BT_SSP_VARIANT_CONSENT
     * For BT_SSP_VARIANT_PASSKEY_ENTRY, if accept==FALSE, then passkey
     * shall be zero */
    int (*ssp_reply)(const bt_bdaddr_t *bd_addr, bt_ssp_variant_t variant,
                     uint8_t accept, uint32_t passkey);

    /** Get Bluetooth profile interface */
    const void* (*get_profile_interface) (const char *profile_id);

    /** Bluetooth Test Mode APIs - Bluetooth must be enabled for these APIs */
    /* Configure DUT Mode - Use this mode to enter/exit DUT mode */
    int (*dut_mode_configure)(uint8_t enable);

    /* Send any test HCI (vendor-specific) command to the controller. Must be in DUT Mode */
    int (*dut_mode_send)(uint16_t opcode, uint8_t *buf, uint8_t len);
    /** BLE Test Mode APIs */
    /* opcode MUST be one of: LE_Receiver_Test, LE_Transmitter_Test, LE_Test_End */
    int (*le_test_mode)(uint16_t opcode, uint8_t *buf, uint8_t len);

    /* enable or disable bluetooth HCI snoop log */
    int (*config_hci_snoop_log)(uint8_t enable);

    /** Sets the OS call-out functions that bluedroid needs for alarms and wake locks.
      * This should be called immediately after a successful |init|.
      */
    int (*set_os_callouts)(bt_os_callouts_t *callouts);

    /** Read Energy info details - return value indicates BT_STATUS_SUCCESS or BT_STATUS_NOT_READY
      * Success indicates that the VSC command was sent to controller
      */
    int (*read_energy_info)();

    /**
     * Native support for dumpsys function
     * Function is synchronous and |fd| is owned by caller.
     */
    void (*dump)(int fd);

    /**
     * Clear /data/misc/bt_config.conf and erase all stored connections
     */
    int (*config_clear)(void);

    /**
     * Clear (reset) the dynamic portion of the device interoperability database.
     */
    void (*interop_database_clear)(void);

    /**
     * Add a new device interoperability workaround for a remote device whose
     * first |len| bytes of the its device address match |addr|.
     * NOTE: |feature| has to match an item defined in interop_feature_t (interop.h).
     */
    void (*interop_database_add)(uint16_t feature, const bt_bdaddr_t *addr, size_t len);
} bt_interface_t;

/** TODO: Need to add APIs for Service Discovery, Service authorization and
  *       connection management. Also need to add APIs for configuring
  *       properties of remote bonded devices such as name, UUID etc. */

typedef struct {
    struct hw_device_t common;
    const bt_interface_t* (*get_bluetooth_interface)();
} bluetooth_device_t;

typedef bluetooth_device_t bluetooth_module_t;

3.3 蓝牙搜索流程

• BluetoothSetting->LocalBluetoothAdapter->BluetoothAdapter->IBluetooth.stub->AdapterService

• AdapterService->JNI->bluetooth.h

4. 应用层开发

蓝牙app开发，官方文档说明的已经很详细，链接如下：

• 传统蓝牙部分
• BLE部分