关键词：蓝牙blueZ  A2DP、SINK、sink_connect、sink_disconnect、sink_suspend、sink_resume、sink_is_connected、sink_get_properties、AUDIO、DBUS
版本号：基于android4.2之前版本号 bluez
内核：linux/linux3.08
系统：android/android4.1.3.4
作者：xubin341719(欢迎转载。请注明作者。请尊重版权谢谢)
欢迎指正错误。共同学习、共同进步！！

參考站点：
http://blog.csdn.net/u011960402/article/details/17216563
http://www.cnblogs.com/fityme/archive/2013/04/13/3019471.html socket相关
http://hi.baidu.com/wwwkljoel/item/a35e5745d14e02e6bcf45170 setsockopt

Android bluetooth介绍（一）：基本概念及硬件接口
Android bluetooth介绍（二）： android 蓝牙代码架构及其uart 到rfcomm流程
Android bluetooth介绍（三）： 蓝牙扫描(scan)设备分析
Android bluetooth介绍（四）： a2dp connect流程分析

一、蓝牙扫描经常使用的方法：
         蓝牙扫描的能够通过两种途径实现：命令行hciitool扫描；Android界面触发，通过JNI、DUBS下发命令。

1、  命令行hciitool扫描（这部分通过Linux命令操作，跟android没有关系）
 通过bluez的tool发送扫描命令，如：hcitoool scan
adb shell 下#hcitool  scan扫描结果

Hcitool扫描逻辑例如以下所看到的：

2、Android界面触发，通过JNI、DUBS下发命令：通过android界面点击搜索设备

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应用扫描触发逻辑流程：自上而下三种颜色，分别代表应用部分、JNI部分、linux blueZ部分。

二、Hcitool触发逻辑分析
1、hcitool这部分代码比較简单，实现函数
idh.code\external\bluetooth\bluez\tools\hcitool.c代码大致流程例如以下：

通过所带的參数，找到cmd_scan,进入hci_inquriy。这个函数中创建一个BTPROTO_HCI的socket,通过ioctlHCINQUIRY向内核读取数据，保存返回信息。

2、内核层逻辑：
 当然IOCTL仅仅是当中一项。
idh.code\kernel\net\bluetooth\ hci_sock.c

static const struct proto_ops hci_sock_ops = {

…………

	.ioctl		= hci_sock_ioctl,

	.poll		= datagram_poll,

	.listen		= sock_no_listen,

…………

};

它的流程就是构造查询命令，放入命令队列，调度队列来发送命令，当中hci_send_frame后面会解说，这里关键是命令的发送和数据的收集是分开的。所以它在里面会放弃2s的调度。以此来等待数据的收集。收集的数据放在hdev->inq_cache里面。我们来看看这个数据是怎样取得的。例如以下图所看到的：

入口点hci_rx_work前面已经具体分析过了，这里就不说了。它里面会依据不同的事件类型做不同的处理。通常情况下，扫描都是带信号强度的扫描。所以走的hci_inquiry_result_with_rssi_evt路线，还有其他几种扫描方式，比方：HCI_EV_INQUIRY_RESULT，HCI_EV_EXTENDED_INQUIRY_RESULT等。处理逻辑都几乎相同的，里面会hci_inquiry_cache_update来把结果放到hdev->discovery链表里面去。供后面的查询；比方前面调用的inquiry_cache_dump函数就能够从这个链表里面把数据取出来。然后copy到用户层；
三、Android界面触发，通过JNI、DUBS下发命令
 总体流程例如以下所看到的：

（一）、应用部分：
1、 idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\DeviceListPreferenceFragment.java

  @Override

    public boolean onPreferenceTreeClick(PreferenceScreen preferenceScreen,

        Preference preference) {

     	…………

        mLocalAdapter.startScanning(true);

        return true;

      }

2、 idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\LocalBluetoothAdapter.java

 private final BluetoothAdapter mAdapter;

 void startScanning(boolean force) {

        // Only start if we're not already scanning

        if (!mAdapter.isDiscovering()) {

            if (!force) {

                // Don't scan more than frequently than SCAN_EXPIRATION_MS,

                // unless forced

                if (mLastScan + SCAN_EXPIRATION_MS > System.currentTimeMillis()) {

                    return;

                }

                // If we are playing music, don't scan unless forced.

                A2dpProfile a2dp = mProfileManager.getA2dpProfile();

                if (a2dp != null && a2dp.isA2dpPlaying()) {

                    return;

                }

            }

            if (mAdapter.startDiscovery()) {

                mLastScan = System.currentTimeMillis();

            }

        }

}

3、idh.code\frameworks\base\core\java\android\bluetooth\BluetoothAdapter.java

    public boolean startDiscovery() {

        if (getState() != STATE_ON) return false;

        try {

            return mService.startDiscovery();

        } catch (RemoteException e) {Log.e(TAG, "", e);}

        return false;

    }

4、JNI函数的调用idh.code\frameworks\base\core\java\android\server\BluetoothService.java

private native boolean startDiscoveryNative();//Native函数声明

public class BluetoothService extends IBluetooth.Stub {

    private static final String TAG = "BluetoothService";

    private static final boolean DBG = true;

…………

public synchronized boolean startDiscovery() {

mContext.enforceCallingOrSelfPermission(BLUETOOTH_ADMIN_PERM,

        "Need BLUETOOTH_ADMIN permission");

        if (!isEnabledInternal()) return false;

        return startDiscoveryNative();

}

………………

}

（二）、JNI部分：
1、android_server_BluetoothService.cpp中JNI函数的对比表
idh.code\frameworks\base\core\jni\android_server_BluetoothService.cpp

static JNINativeMethod sMethods[] = {

     /* name, signature, funcPtr */

   ………………

    {"startDiscoveryNative", "()Z", (void*)startDiscoveryNative},

{"stopDiscoveryNative", "()Z", (void *)stopDiscoveryNative},

…………

}

2、相应Native函数的实现
这里面有个知识点DBUS，这个后面我们单独去解说
idh.code\frameworks\base\core\jni\android_server_BluetoothService.cpp

#define BLUEZ_DBUS_BASE_IFC       "org.bluez"

#define DBUS_ADAPTER_IFACE BLUEZ_DBUS_BASE_IFC ".Adapter"//事实上DBUS_ADAPTER_IFACE 也就是 org.bluez.Adapter

static jboolean startDiscoveryNative(JNIEnv *env, jobject object) {

………………

    /* Compose the command */

    msg = dbus_message_new_method_call(BLUEZ_DBUS_BASE_IFC,

                                       get_adapter_path(env, object),

                                       DBUS_ADAPTER_IFACE, "StartDiscovery");

…………

}

Native函数startDiscoveryNative和字符串StartDiscovery相应。

（三）、DBUS部分

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1、DBUS相应方法的实现，这里跟JNI部分比較相似，也是用了函数结构体相应关系。
idh.code\external\bluetooth\bluez\src\adapter.c

#define ADAPTER_INTERFACE	"org.bluez.Adapter"

static GDBusMethodTable adapter_methods[] = {

………………

	{ "ReleaseSession",	"",	"",	release_session		},

	{ "StartDiscovery",	"",	"",	adapter_start_discovery },

	{ "StopDiscovery",	"",	"",	adapter_stop_discovery,

						G_DBUS_METHOD_FLAG_ASYNC},

………………

}

字符StartDiscovery又相应C中的实现函数adapter_start_discovery。
2、adapter_start_discovery的实现
idh.code\external\bluetooth\bluez\src\adapter.c

static DBusMessage *adapter_start_discovery(DBusConnection *conn,

						DBusMessage *msg, void *data)

{

…………

	err = start_discovery(adapter);

	if (err < 0 && err != -EINPROGRESS)

		return btd_error_failed(msg, strerror(-err));

done:

	req = create_session(adapter, conn, msg, 0,

				session_owner_exit);

	adapter->disc_sessions = g_slist_append(adapter->disc_sessions, req);

	return dbus_message_new_method_return(msg);

}

3、 start_discovery调用
idh.code\external\bluetooth\bluez\src\adapter.c

const struct btd_adapter_ops *adapter_ops = NULL;

static int start_discovery(struct btd_adapter *adapter)

{

…………

	pending_remote_name_cancel(adapter);

	return adapter_ops->start_discovery(adapter->dev_id);

}

adapter_ops相应结构体btd_adapter_ops中相应函数，例如以下：上面部分就相应到btd_adapter_ops中的hci_ops结构体。

4、btd_adapter_ops中的hci_ops结构体
idh.code\external\bluetooth\bluez\plugins\hciops.c

static struct btd_adapter_ops hci_ops = {

…………

	.set_powered = hciops_set_powered,

	.set_discoverable = hciops_set_discoverable,

	.set_pairable = hciops_set_pairable,

	.set_limited_discoverable = hciops_set_limited_discoverable,

	.start_discovery = hciops_start_discovery,

	.stop_discovery = hciops_stop_discovery,

	………………

	.create_bonding = hciops_create_bonding,

	.cancel_bonding = hciops_cancel_bonding,

	.read_local_oob_data = hciops_read_local_oob_data,

	.add_remote_oob_data = hciops_add_remote_oob_data,

	.remove_remote_oob_data = hciops_remove_remote_oob_data,

	.set_link_timeout = hciops_set_link_timeout,

	.retry_authentication = hciops_retry_authentication,

};

5、hciops_start_discovery函数的实现
idh.code\external\bluetooth\bluez\plugins\hciops.c

static int hciops_start_discovery(int index)

{

	int adapter_type = get_adapter_type(index);

	switch (adapter_type) {

	case BR_EDR_LE:

		return hciops_start_inquiry(index, LENGTH_BR_LE_INQ);

	case BR_EDR: //蓝牙芯片为2.1+EDR的

		return hciops_start_inquiry(index, LENGTH_BR_INQ);

	case LE_ONLY:

		return hciops_start_scanning(index, TIMEOUT_LE_SCAN);

	default:

		return -EINVAL;

	}

}

6、hciops_start_inquiry
idh.code\external\bluetooth\bluez\plugins\hciops.c

static int hciops_start_inquiry(int index, uint8_t length)

{

	struct dev_info *dev = &devs[index];

	uint8_t lap[3] = { 0x33, 0x8b, 0x9e };

	inquiry_cp inq_cp;

	DBG("hci%d length %u", index, length);

	memset(&inq_cp, 0, sizeof(inq_cp));

	memcpy(&inq_cp.lap, lap, 3);

	inq_cp.length = length;

	inq_cp.num_rsp = 0x00;

	if (hci_send_cmd(dev->sk, OGF_LINK_CTL,

			OCF_INQUIRY, INQUIRY_CP_SIZE, &inq_cp) < 0)

		return -errno;

	return 0;

}

7、idh.code\external\bluetooth\bluez\lib\hci.c

/* HCI functions that require open device

 * dd - Device descriptor returned by hci_open_dev. */

dd = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);

int hci_send_cmd(int dd, uint16_t ogf, uint16_t ocf, uint8_t plen, void *param)

{

………………

	if (plen) {

		iv[2].iov_base = param;

		iv[2].iov_len  = plen;

		ivn = 3;

	}

	while (writev(dd, iv, ivn) < 0) {//writev这里把数据写到socket里面。

		if (errno == EAGAIN || errno == EINTR)

			continue;

		return -1;

	}

	return 0;

}

（四）、内核部分：
1、HCI FILTER的设置
 HCIsocket的类型为BTPROTO_HCI。上层调用setsockopt的时候。触发了内核的hci_sock_setsockopt函数的运行。在这里面设置了socket的filter特性，包含包类型，包含事件类型；

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当上层调用setsockopt(sock, SOL_HCI, HCI_FILTER,&flt, sizeof(flt))时。触发相应的内核路径。
idh.code\kernel\net\bluetooth\hci_sock.c

static const struct proto_ops hci_sock_ops = {

	.family		= PF_BLUETOOTH,

	.owner		= THIS_MODULE,

…………

	.shutdown	= sock_no_shutdown,

	.setsockopt	= hci_sock_setsockopt,

	.getsockopt	= hci_sock_getsockopt,

	.connect	= sock_no_connect,

…………

};

idh.code\kernel\net\bluetooth\hci_sock.c

static int hci_sock_setsockopt(struct socket *sock, int level, int optname, char __user *optval, unsigned int len)

{

………………

	case HCI_FILTER:

		{

			struct hci_filter *f = &hci_pi(sk)->filter;

			uf.type_mask = f->type_mask;

			uf.opcode    = f->opcode;

			uf.event_mask[0] = *((u32 *) f->event_mask + 0);

			uf.event_mask[1] = *((u32 *) f->event_mask + 1);

		}

	………………

}

内核这部分就比較统一的数据，通过hci_send_cmd把命令发出去，HCI_FILTER这个地方的处理还没理解。后面补充。

Writev函数通过socket把数据写下去，经过VFS层，调用到内核空间的sendmsg函数。

（五）、EVENT返回状态

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Controller收到查询命令后。返回一个命令状态
1、cmd_status
idh.code\external\bluetooth\bluez\plugins\hciops.c

	switch (eh->evt) {

	case EVT_CMD_STATUS:

		cmd_status(index, ptr);

		break;

static inline void cmd_status(int index, void *ptr)

{

	evt_cmd_status *evt = ptr;

	uint16_t opcode = btohs(evt->opcode);

	if (opcode == cmd_opcode_pack(OGF_LINK_CTL, OCF_INQUIRY))//假设是inquriy做特殊处理；

		cs_inquiry_evt(index, evt->status);

}

2、cs_inquiry_evt的实现 idh.code\external\bluetooth\bluez\plugins\hciops.c

static inline void cs_inquiry_evt(int index, uint8_t status)

{

	if (status) {//错误信息

		error("Inquiry Failed with status 0x%02x", status);

		return;

	}

	set_state(index, DISCOV_INQ);//设置状态为INQ，向上层回复discoverying的property change

}

3、设置不同的DISCOV 状态 idh.code\external\bluetooth\bluez\plugins\hciops.c

static void set_state(int index, int state)

{

	………………

	switch (dev->discov_state) {

	case DISCOV_HALTED://停止发现;

		if (adapter_get_state(adapter) == STATE_SUSPENDED)

			return;

		if (is_resolvname_enabled() &&

					adapter_has_discov_sessions(adapter))

			adapter_set_state(adapter, STATE_RESOLVNAME);

		else

			adapter_set_state(adapter, STATE_IDLE);

		break;

	case DISCOV_INQ:

	case DISCOV_SCAN://扫描发现；

		adapter_set_state(adapter, STATE_DISCOV);

		break;

	}

}

4、设置adapter的状态 idh.code\external\bluetooth\bluez\src\adapter.c

idh.code\external\bluetooth\bluez\src\adapter.c

#define ADAPTER_INTERFACE	"org.bluez.Adapter"

void adapter_set_state(struct btd_adapter *adapter, int state)

{

…………

	case STATE_DISCOV:

		discov_active = TRUE;

//向上层回复discovering的property change

		emit_property_changed(connection, path,

					ADAPTER_INTERFACE, "Discovering",

					DBUS_TYPE_BOOLEAN, &discov_active);

		break;

…………

}

emit_property_changed发送PropertyChanged的消息，消息内容为Discovering。通知上层BluetoothEventLoop进行Discovering。

5、emit_property_changed发送Discovering消息的实现 idh.code\external\bluetooth\bluez\src\dbus-common.c
 这部分涉及到DBUS内容

dbus_bool_t emit_property_changed(DBusConnection *conn,

					const char *path,

					const char *interface,

					const char *name,

					int type, void *value)

{

	DBusMessage *signal;

	DBusMessageIter iter;

	signal = dbus_message_new_signal(path, interface, "PropertyChanged"); // 创建消息对象并标识路径

	if (!signal) {

		error("Unable to allocate new %s.PropertyChanged signal",

				interface);

		return FALSE;

	}

	dbus_message_iter_init_append(signal, &iter);//把信号相相应的參数压进去

	dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, &name);//申请一个首地址。把前面压入的參数传入这个首地址

append_variant(&iter, type, value);//

	return g_dbus_send_message(conn, signal);//启动发送调用，并释放发送相关消息信息

}

6、DBUS消息接收的实现 idh.code\frameworks\base\core\jni\android_server_BluetoothEventLoop.cpp

// Called by dbus during WaitForAndDispatchEventNative()

static DBusHandlerResult event_filter(DBusConnection *conn, DBusMessage *msg,

                                      void *data) {

…………

else if (dbus_message_is_signal(msg, "org.bluez.Adapter", "PropertyChanged")) {

        jobjectArray str_array = parse_adapter_property_change(env, msg);//（1）、对收到消息的解析

        if (str_array != NULL) {

            /* Check if bluetoothd has (re)started, if so update the path. */

            jstring property =(jstring) env->GetObjectArrayElement(str_array, 0);

            const char *c_property = env->GetStringUTFChars(property, NULL);

            if (!strncmp(c_property, "Powered", strlen("Powered"))) {

                jstring value =

                    (jstring) env->GetObjectArrayElement(str_array, 1);

                const char *c_value = env->GetStringUTFChars(value, NULL);

                if (!strncmp(c_value, "true", strlen("true")))

                    nat->adapter = get_adapter_path(nat->conn);

                env->ReleaseStringUTFChars(value, c_value);

            }

            env->ReleaseStringUTFChars(property, c_property);

            env->CallVoidMethod(nat->me,

                              method_onPropertyChanged,//（2）、

method_onPropertyChanged NATVIE函数的实现

                              str_array);

        } else LOG_AND_FREE_DBUS_ERROR_WITH_MSG(&err, msg);

        goto success;

}

（1）、对收到消息的解析 idh.code\frameworks\base\core\jni\android_bluetooth_common.cpp

jobjectArray parse_adapter_property_change(JNIEnv *env, DBusMessage *msg) {

    return parse_property_change(env, msg, (Properties *) &adapter_properties,

                    sizeof(adapter_properties) / sizeof(Properties));

}

针对org.bluez.Adapter不同的消息类型
idh.code\frameworks\base\core\jni\android_bluetooth_common.cpp

static Properties adapter_properties[] = {

    {"Address", DBUS_TYPE_STRING},

    {"Name", DBUS_TYPE_STRING},

    {"Class", DBUS_TYPE_UINT32},

    {"Powered", DBUS_TYPE_BOOLEAN},

    {"Discoverable", DBUS_TYPE_BOOLEAN},

    {"DiscoverableTimeout", DBUS_TYPE_UINT32},

    {"Pairable", DBUS_TYPE_BOOLEAN},

    {"PairableTimeout", DBUS_TYPE_UINT32},

    {"Discovering", DBUS_TYPE_BOOLEAN},

    {"Devices", DBUS_TYPE_ARRAY},

    {"UUIDs", DBUS_TYPE_ARRAY},

};

（2）、method_onPropertyChanged NATVIE函数的实现 idh.code\frameworks\base\core\jni\android_server_BluetoothEventLoop.cpp

static void classInitNative(JNIEnv* env, jclass clazz) {

    ALOGV("%s", __FUNCTION__);

#ifdef HAVE_BLUETOOTH

    method_onPropertyChanged = env->GetMethodID(clazz, "onPropertyChanged",

                                                "([Ljava/lang/String;)V");

method_onDevicePropertyChanged = env->GetMethodID(clazz,

 "onDevicePropertyChanged","(Ljava/lang/String;[Ljava/lang/String;)V");

…………

}

7、JNI调用onPropertyChanged相应JAVA的实现，在BluetoothEventLoop.java
idh.code\frameworks\base\core\java\android\server\BluetoothEventLoop.java中

   private static native void classInitNative();

/*package*/ void onPropertyChanged(String[] propValues) {

 ………………

        log("Property Changed: " + propValues[0] + " : " + propValues[1]);

        String name = propValues[0];

        if (name.equals("Name")) {//获取蓝牙名字；

   			…………

        } else if (name.equals("Pairable") || name.equals("Discoverable")) {//配对。

           ………………

        } else if (name.equals("Discovering")) {//扫描查询；

            Intent intent;

            adapterProperties.setProperty(name, propValues[1]);

            if (propValues[1].equals("true")) {

                intent = new Intent(BluetoothAdapter.ACTION_DISCOVERY_STARTED);

            } else {

                // Stop the discovery.

                mBluetoothService.cancelDiscovery();

                intent = new Intent(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);

            }

            mContext.sendBroadcast(intent, BLUETOOTH_PERM);

        } else if (name.equals("Devices") || name.equals("UUIDs")) {//Devices、UUID的获取；

     	………………

        } else if (name.equals("Powered")) {//蓝牙打开、关闭；

            mBluetoothState.sendMessage(BluetoothAdapterStateMachine.POWER_STATE_CHANGED,

                propValues[1].equals("true") ? new Boolean(true) : new Boolean(false));

        } else if (name.equals("DiscoverableTimeout")) {

            adapterProperties.setProperty(name, propValues[1]);

        }

    }

（1）、看到这份log我们或许会更明确其他功能的由来： 

D BluetoothEventLoop: Property Changed: Powered : true

D BluetoothEventLoop: Property Changed: Pairable : true

D BluetoothEventLoop: Property Changed: Class : 5898764

D BluetoothEventLoop: Property Changed: Pairable : true

D BluetoothEventLoop: Property Changed: Discoverable : false

D BluetoothEventLoop: Property Changed: Discovering : true

D BluetoothEventLoop: Property Changed: Discovering : false

D BluetoothEventLoop: Property Changed: Devices : 1

D BluetoothEventLoop: Device property changed: 94:20:53:01:15:90 property: Connected value: true

D BluetoothEventLoop: Device property changed: 94:20:53:01:15:90 property: Paired value: true

D BluetoothEventLoop: Device property changed: 94:20:53:01:15:90 property: UUIDs value: 4

（2）、以下我们重点分析Discovering这部分：
idh.code\frameworks\base\core\java\android\server\BluetoothEventLoop.java

else if (name.equals("Discovering")) {

            Intent intent;

            adapterProperties.setProperty(name, propValues[1]);

            if (propValues[1].equals("true")) {//開始扫描

                intent = new Intent(BluetoothAdapter.ACTION_DISCOVERY_STARTED);//

            } else {

                // Stop the discovery. //停止扫描

                mBluetoothService.cancelDiscovery();

                intent = new Intent(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);

            }

            mContext.sendBroadcast(intent, BLUETOOTH_PERM);

        }

这样就能够通过broadcast发送ACTION_DISCOVERY_STARTED广播，注冊的receiver来响应了。

8、ACTION_DISCOVERY_STARTED\ACTION_DISCOVERY_FINISHED的receiver分析
 从代码中我们能够看到这个action一共同拥有两个receiver，一个是静态注冊的BluetoothDiscoveryReceiver,一个是动态注冊是ScanningStateChangedHandler。
（1）、BluetoothDiscoveryReceiver：这个receiver是在settings中的Androidmanifest中静态注冊的。用途：主要用于获取扫描開始和终止的时间。
idh.code\packages\apps\Settings\AndroidManifest.xml

<receiver

      android:name=".bluetooth.BluetoothDiscoveryReceiver">

      <intent-filter>

        <action android:name="android.bluetooth.adapter.action.DISCOVERY_STARTED" />

        <action android:name="android.bluetooth.adapter.action.DISCOVERY_FINISHED" />

        <category android:name="android.intent.category.DEFAULT" />

       </intent-filter>

</receiver>

1）、ACTION_DISCOVERY_STARTED、ACTION_DISCOVERY_FINISHED和AndroidManifest.xml文件的联系
idh.code\frameworks\base\core\java\android\bluetooth\BluetoothAdapter.java

public final class BluetoothAdapter {

    private static final String TAG = "BluetoothAdapter";

private static final boolean DBG = false;

…………

    public static final String ACTION_DISCOVERY_STARTED =

            "android.bluetooth.adapter.action.DISCOVERY_STARTED";

    public static final String ACTION_DISCOVERY_FINISHED =

            "android.bluetooth.adapter.action.DISCOVERY_FINISHED";

…………

}

2）、BluetoothAdapter，蓝牙适配器。直到我们建立bluetoothSocket连接之前。都要不断操作它。

BluetoothAdapter中的动作常量

ACTION_DISCOVERY_FINISHED

已完毕蓝牙搜索

ACTION_DISCOVERY_STARTED

已经開始搜索蓝牙设备

ACTION_LOCAL_NAME_CHANGED

更改蓝牙的名字

ACTION_REQUEST_DISCOVERABLE

请求能够被搜索

ACTION_REQUEST_ENABLE

请求启动蓝牙

ACTION_SCAN_MODE_CHANGED

扫描模式已经改变

ACTION_STATE_CHANGED

状态已改变

ACTION_CONNECTION_STATE_CHANGED

3）、收到广播后函数实现，開始扫描
 Main log中显示的log为DISCOVERY_STARTED
D BluetoothDiscoveryReceiver: Received:android.bluetooth.adapter.action.DISCOVERY_STARTED
HCI log 中：

watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQveHViaW4zNDE3MTk=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" alt="" />

idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\BluetoothDiscoveryReceiver.java这个文件里就一个函数。还是比简单

public final class BluetoothDiscoveryReceiver extends BroadcastReceiver {

    private static final String TAG = "BluetoothDiscoveryReceiver";

    private static final boolean DEBUG = Debug.isDebug();

    @Override

    public void onReceive(Context context, Intent intent) {

        String action = intent.getAction();

        if (DEBUG) Log.d(TAG, "Received: " + action);

        if (action.equals(BluetoothAdapter.ACTION_DISCOVERY_STARTED) ||

                action.equals(BluetoothAdapter.ACTION_DISCOVERY_FINISHED)) {

//共享时间戳。扫描開始和结束的时间。

   LocalBluetoothPreferences.persistDiscoveringTimestamp(context);

        }

    }

}

ScanningStateChangedHandler的注冊及用途，要用于開始扫描。和扫描显示界面的控制。

这个receiver是在idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\BluetoothEventManager.java动态注冊的，例如以下：

BluetoothEventManager(LocalBluetoothAdapter adapter,

            CachedBluetoothDeviceManager deviceManager, Context context) {

mLocalAdapter = adapter;

…………

// Bluetooth on/off broadcasts

 addHandler(BluetoothAdapter.ACTION_STATE_CHANGED, new AdapterStateChangedHandler());

// Discovery broadcastsaddHandler(BluetoothAdapter.ACTION_DISCOVERY_STARTED, new ScanningStateChangedHandler(true));

        addHandler(BluetoothAdapter.ACTION_DISCOVERY_FINISHED, new ScanningStateChangedHandler(false));

…………

}

（1）、ScanningStateChangedHandler函数实现例如以下：idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\BluetoothEventManager.java

 private class ScanningStateChangedHandler implements Handler {

        private final boolean mStarted;

        ScanningStateChangedHandler(boolean started) {

            mStarted = started;

        }

        public void onReceive(Context context, Intent intent,

                BluetoothDevice device) {

            synchronized (mCallbacks) {//1)、调用注冊的callback

中的onScanningStateChanged函数。

for (BluetoothCallback callback : mCallbacks) {

                    callback.onScanningStateChanged(mStarted);

                }

            }

//2）、这个函数就是把上次扫描到设备、和之前的设备做相应处理；

            mDeviceManager.onScanningStateChanged(mStarted);

            LocalBluetoothPreferences.persistDiscoveringTimestamp(context);

        }

}

1）、调用注冊的callback中的callback.onScanningStateChanged(mStarted)函数。
idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\DeviceListPreferenceFragment.java

    public void onScanningStateChanged(boolean started) {

        if (started == false) {//《1》、假设扫描结束；

            removeOutOfRangeDevices();

        }

        updateProgressUi(started);// 《2》、UI显示小圆圈扫描；

}

《1》、假设扫描结束；removeOutOfRangeDevices();
idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\DeviceListPreferenceFragment.java

private void removeOutOfRangeDevices() {

    Collection<CachedBluetoothDevice> cachedDevices =

            mLocalManager.getCachedDeviceManager().getCachedDevicesCopy();

    for (CachedBluetoothDevice cachedDevice : cachedDevices) {

         if (cachedDevice.getBondState() == BluetoothDevice.BOND_NONE &&

             cachedDevice.isVisible() == false) {

             BluetoothDevicePreference preference = mDevicePreferenceMap.get(cachedDevice);

             if (preference != null) {

                 mDeviceListGroup.removePreference(preference);

             }

             mDevicePreferenceMap.remove(cachedDevice);

          }

     }

}

《2》、UI显示小圆圈扫描，updateProgressUi(started)；例如以下图所看到的：

idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\DeviceListPreferenceFragment.java

private void updateProgressUi(boolean start) {

    if (mDeviceListGroup instanceof ProgressCategory) {

        ((ProgressCategory) mDeviceListGroup).setProgress(start);

    }

}

2）、这部分的作用，開始扫描，不显示列表中内容，或把之前列表中没扫描到的设备清除
mDeviceManager.onScanningStateChanged(mStarted);
idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\CachedBluetoothDevice.java

private void updateProgressUi(boolean start) {

    if (mDeviceListGroup instanceof ProgressCategory) {

        ((ProgressCategory) mDeviceListGroup).setProgress(start);

    }

}

2）、这部分的作用，開始扫描。不显示列表中内容，或把之前列表中没扫描到的设备清除

mDeviceManager.onScanningStateChanged(mStarted);

idh.code\packages\apps\Settings\src\com\android\settings\bluetooth\ CachedBluetoothDevice.java

    public synchronized void onScanningStateChanged(boolean started) {

        // If starting a new scan, clear old visibility

        // Iterate in reverse order since devices may be removed.

        //假设開始新的扫描，清除旧的能见设备。迭代反序由于有的设备可能被删除

        for (int i = mCachedDevices.size() - 1; i >= 0; i--) {

            CachedBluetoothDevice cachedDevice = mCachedDevices.get(i);

            if (started) {//假设扫描開始就不显示；

                cachedDevice.setVisible(false);

            } else {//对扫描的结果作出推断。假设之前扫描过，这次没有扫描到，就移除列表。

                if (cachedDevice.getBondState() == BluetoothDevice.BOND_NONE &&

                        cachedDevice.isVisible() == false) {

                    mCachedDevices.remove(cachedDevice);

                }

            }

        }

    }

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