android 蓝牙bluetooth 4.2.2搜索蓝牙功能实现

       看下蓝牙搜索的流程，触发蓝牙搜索的条件形式上有两种，一是在蓝牙设置界面开启蓝牙会直接开始搜索，另一个是先打开蓝牙开关在进入蓝牙设置界面也会触发搜索，也可能还有其它触发方式，但最后都要来到BluetoothSettngs.java的startScanning()，我们分析的起点也从这里开始，起步代码如下

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private void updateContent(int bluetoothState, boolean scanState) {  

    if (numberOfPairedDevices == 0) {  

         preferenceScreen.removePreference(mPairedDevicesCategory);  

         if (scanState == true) {  

             mActivityStarted = false;  

             startScanning();  

        } else<span style="font-family: Arial, Helvetica, sans-serif;">    ........</span>  

}         

private void startScanning() {  

        if (!mAvailableDevicesCategoryIsPresent) {  

            getPreferenceScreen().addPreference(mAvailableDevicesCategory);  

        }  

        mLocalAdapter.startScanning(true);  

    }  

        其实在这里蓝牙搜索和打开流程是结构上是一致的，利用LocalBluetoothAdapter.java过渡到BluetoothAdapter.java再跳转至AdapterService.java要稍微留意下的是在这个过渡中startScaning()方法变成了startDiscovery()方法，看下代码：packages/apps/Settings/src/com/android/settings/bluetooth/LocalBluetoothAdapter.java

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void startScanning(boolean force) {  

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;  

         }  

     }  

//这里才是我们最关注的，前面限制条件关注一下就行了  

     if (mAdapter.startDiscovery()) {  

         mLastScan = System.currentTimeMillis();  

     }  

}  

       BluetoothAdapter.java的那一段，路径 /frameworks/base/core/java/android/bluetooth/BluetoothAdapter.java

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public boolean startDiscovery() {  

    .............................  

    AdapterService service = getService();  

    if (service == null) return false;  

    return service.startDiscovery();  

}  

      这个service代码写得很明白AdapterService，转了一圈从framework又回到packages了，

      下面的代码路径自然是 :packages/apps/Bluetooth/src/com/android/bluetooth/btservice/AdapterService.java，

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boolean startDiscovery() {  

    enforceCallingOrSelfPermission(BLUETOOTH_ADMIN_PERM,  

            "Need BLUETOOTH ADMIN permission");  

  

    return startDiscoveryNative();  

}  

      和打开蓝牙根本就是一个套路，上面的流程略过一小步，很简单的不写了，下面要怎么走，估计大家也都猜到了，JNI应该出场了，

       路径：/packages/apps/Bluetooth/jni/com_android_bluetooth_btservice_AdapterService.cpp

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

    ALOGV("%s:",__FUNCTION__);                                  

                                                                

    jboolean result = JNI_FALSE;                                

    if (!sBluetoothInterface) return result;                    

                                                                

    int ret = sBluetoothInterface->start_discovery();           

    result = (ret == BT_STATUS_SUCCESS) ? JNI_TRUE : JNI_FALSE;  

    return result;                                              

}   

      在下面要去哪？稍微要动下脑筋，不过我们在上一篇android
-- 蓝牙 bluetooth （二） 打开蓝牙已经说过怎么找了，注意android.mk文件，先找头文件，再找对应的实现C文件代码。就是现在回顾下，蓝牙打开和搜索的代码流程我们都看了，跳转都是一个套路，settings界面发起，LocalBluetoothAdapter.java过渡，去framework的转转（BluetoothAdapter.java）后回到packages的AdapterService.java，再走JNI来的external。流程就是这样的，相信类似的功能跳转(比如蓝牙配对，关闭蓝牙，停止扫描这些)大家都应该熟悉了，后面再有类似的功能就写函数名一笔带过了，还有这里要注意的就是这个start_discovery()实现代码的寻找，留意mk文件就是了，不复杂。小结结束，继续看代码
   路径：/external/bluetooth/bluedroid/btif/src/bluetooth.c

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static int start_discovery(void)  

{  

    /* sanity check */  

    if (interface_ready() == FALSE)  

        return BT_STATUS_NOT_READY;  

  

    return btif_dm_start_discovery();  

}     

        下面代码直接跳转就可以找到，路径external/bluetooth/bluedroid/btif/src/btif_dm.c  

        这个代码有点多，不过里面的信息也很多，所以连注释也一起保留的贴出来了，蓝牙的搜索实现并没有像蓝牙打开那样交由vendor厂商实现，在这里已经写出来了，仔细看下那些#if和#else，都是一些查询条件的调置，#if (BLE_INCLUDED == TRUE)   这个应该就google为蓝牙4.0 LE作的准备了，也算是今年google I/O大会上宣布即将支持蓝牙4.0低能耗版一个佐证吧，对于代码里面那些字符串的含义看这里好了external/bluetooth/bluedroid/bta/include/bta_api.h，一个头文件，大部分字符串和结构体的定义都在这了，多少还有些注释。

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bt_status_t btif_dm_start_discovery(void)                                    

{                                                                            

    tBTA_DM_INQ inq_params;                                                  

    tBTA_SERVICE_MASK services = 0;                                          

                                                                             

    BTIF_TRACE_EVENT1("%s", __FUNCTION__);                                   

    /* TODO: Do we need to handle multiple inquiries at the same time? */    

                                                                             

    /* Set inquiry params and call API */                                    

#if (BLE_INCLUDED == TRUE)                                                   

    inq_params.mode = BTA_DM_GENERAL_INQUIRY|BTA_BLE_GENERAL_INQUIRY;        

#else                                                                        

    inq_params.mode = BTA_DM_GENERAL_INQUIRY;                                

#endif                                                                       

    inq_params.duration = BTIF_DM_DEFAULT_INQ_MAX_DURATION;                  

                                                                             

    inq_params.max_resps = BTIF_DM_DEFAULT_INQ_MAX_RESULTS;                  

    inq_params.report_dup = TRUE;                                            

                                                                             

    inq_params.filter_type = BTA_DM_INQ_CLR;                                 

    /* TODO: Filter device by BDA needs to be implemented here */            

                                                                             

    /* Will be enabled to TRUE once inquiry busy level has been received */  

    btif_dm_inquiry_in_progress = FALSE;                                     

    /* find nearby devices */                                                

    BTA_DmSearch(&inq_params, services, bte_search_devices_evt);             

                                                                             

    return BT_STATUS_SUCCESS;                                                

}   

      BTA_DmSearch()方法是看起来是要搜索了，不过里面这个家伙bte_search_devices_evt才是真正干活的主力，所以我们先看它，在这个函数里

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static void bte_search_devices_evt(tBTA_DM_SEARCH_EVT event, tBTA_DM_SEARCH *p_data)                                                                      {                                                                                                                    

       UINT16 param_len = 0;                                                                                           

                                                                                                                        

       if (p_data)                                                                                                      

           param_len += sizeof(tBTA_DM_SEARCH);                                                                         

       /* Allocate buffer to hold the pointers (deep copy). The pointers will point to the end of the tBTA_DM_SEARCH */  

       switch (event)                                                                                                   

       {                                                                                                                

           case BTA_DM_INQ_RES_EVT:                                                                                     

           {                                                                                                            

               if (p_data->inq_res.p_eir)                                                                               

                   param_len += HCI_EXT_INQ_RESPONSE_LEN;                                                               

           }                                                                                                            

           break;                                                                                                              

          ..............................                                                                                                

       }                                                                                                                

       BTIF_TRACE_DEBUG3("%s event=%s param_len=%d", __FUNCTION__, dump_dm_search_event(event), param_len);             

                                                                                                                        

       /* if remote name is available in EIR, set teh flag so that stack doesnt trigger RNR */                          

       if (event == BTA_DM_INQ_RES_EVT)                                                                                 

           p_data->inq_res.remt_name_not_required = check_eir_remote_name(p_data, NULL, NULL);                          

                                                                                                                        

       btif_transfer_context (btif_dm_search_devices_evt , (UINT16) event, (void *)p_data, param_len,                   

           (param_len > sizeof(tBTA_DM_SEARCH)) ? search_devices_copy_cb : NULL);                                       

   }     

         在上面的这个函数里又有这个bte_search_devices_evt，在它里我们能看一个 HAL_CBACK，这是要往回发消息了，看下这个函数的全貌，说是全貌，不过还是只贴出一个case分支，太长了，大家还是自行还源码吧。到这里已经可以知道扫描到蓝牙设备的mac地址和设备名，那个bdcpy函数就是在解析mac地址，有了这些，蓝牙搜索是到应该在界面展示成果的时候了，开始回调，忘记代码路径了，这个函数都在这个文件里：  /external/bluetooth/bluedroid/btif/src/btif_dm.c

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static void btif_dm_search_devices_evt (UINT16 event, char *p_param)  

  

   tBTA_DM_SEARCH *p_search_data;  

   BTIF_TRACE_EVENT2("%s event=%s", __FUNCTION__, dump_dm_search_event(event));  

  

   switch (event)  

   {  

       case BTA_DM_DISC_RES_EVT:  

       {  

           p_search_data = (tBTA_DM_SEARCH *)p_param;  

           /* Remote name update */  

           if (strlen((const char *) p_search_data->disc_res.bd_name))  

           {  

               bt_property_t properties[1];  

               bt_bdaddr_t bdaddr;  

               bt_status_t status;  

  

               properties[0].type = BT_PROPERTY_BDNAME;  

               properties[0].val = p_search_data->disc_res.bd_name;  

               properties[0].len = strlen((char *)p_search_data->disc_res.bd_name);  

               bdcpy(bdaddr.address, p_search_data->disc_res.bd_addr);  

  

               status = btif_storage_set_remote_device_property(&bdaddr, &properties[0]);  

               ASSERTC(status == BT_STATUS_SUCCESS, "failed to save remote device property", status);  

               HAL_CBACK(bt_hal_cbacks, remote_device_properties_cb,  

                                status, &bdaddr, 1, properties);  

           }  

           /* TODO: Services? */  

       }  

       break;  

       一小段log，下面的文字就在上面的函数里打出来的，即便上面的写的函数没有，肯定也在附近了。

05-30 13:52:14.890  1578  2612 D bt-btif : bte_search_devices_evt event=BTA_DM_INQ_RES_EVT param_len=524

05-30 13:52:14.890  1578  2612 D bt-btif : search_devices_copy_cb: event=BTA_DM_INQ_RES_EVT

05-30 13:52:14.890  1578  2584 I bt-btif : btif_dm_search_devices_evt event=BTA_DM_INQ_RES_EVT

05-30 13:52:14.890  1578  2584 D bt-btif : btif_dm_search_devices_evt() ec:89:f5:ba:fb:03 device_type = 0x1

        当然回过头我们还要看下那个BTA_DmSearch()，看它的实现，更应该是起消息发送的作用，代码在/external/bluetooth/bluedroid/bta/dm/bta_dm_api.c，这个函数具体流程并没有看多少，当工具方法看了，有时间看看还是没坏处的。

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void BTA_DmSearch(tBTA_DM_INQ *p_dm_inq, tBTA_SERVICE_MASK services, tBTA_DM_SEARCH_CBACK *p_cback)  

{  tBTA_DM_API_SEARCH    *p_msg;  

    if ((p_msg = (tBTA_DM_API_SEARCH *) GKI_getbuf(sizeof(tBTA_DM_API_SEARCH))) != NULL)  

    {  

        memset(p_msg, 0, sizeof(tBTA_DM_API_SEARCH));  

  

        p_msg->hdr.event = BTA_DM_API_SEARCH_EVT;  

        memcpy(&p_msg->inq_params, p_dm_inq, sizeof(tBTA_DM_INQ));  

        p_msg->services = services;  

        p_msg->p_cback = p_cback;  

        p_msg->rs_res  = BTA_DM_RS_NONE;  

        bta_sys_sendmsg(p_msg);  

    }  

}  

      看了上面方法后我们 要回去了看看，代码通过JNI下来的，回去也是看JNI的回调方法

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method_deviceFoundCallback = env->GetMethodID(jniCallbackClass, "deviceFoundCallback", "([B)V");  

deviceFoundCallback方法最后会来java层的/packages/apps/Bluetooth/src/com/android/bluetooth/btservice/RemoteDevices.java

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void deviceFoundCallback(byte[] address) {  

       // The device properties are already registered - we can send the intent  

       // now  

       BluetoothDevice device = getDevice(address);  

       debugLog("deviceFoundCallback: Remote Address is:" + device);  

       DeviceProperties deviceProp = getDeviceProperties(device);  

       if (deviceProp == null) {  

           errorLog("Device Properties is null for Device:" + device);  

           return;  

       }  

  

       Intent intent = new Intent(BluetoothDevice.ACTION_FOUND);  

       intent.putExtra(BluetoothDevice.EXTRA_DEVICE, device);  

       intent.putExtra(BluetoothDevice.EXTRA_CLASS,  

               new BluetoothClass(Integer.valueOf(deviceProp.mBluetoothClass)));  

       intent.putExtra(BluetoothDevice.EXTRA_RSSI, deviceProp.mRssi);  

       intent.putExtra(BluetoothDevice.EXTRA_NAME, deviceProp.mName);  

  

       mAdapterService.sendBroadcast(intent, mAdapterService.BLUETOOTH_PERM);  

   }  

        到这里就是给界面发广播，应用层收到广播显示出来，通过这个handle，这个handle可以在BluetoothEventManager.java的构造函数里找到，

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addHandler(BluetoothDevice.ACTION_FOUND, new DeviceFoundHandler());  

    private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {  

    @Override  

    public void onReceive(Context context, Intent intent) {  

        String action = intent.getAction();  

        BluetoothDevice device = intent  

                .getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);  

  

        Handler handler = mHandlerMap.get(action);  

        if (handler != null) {  

            handler.onReceive(context, intent, device);  

        }  

    }  

};  

         这里handle对应要看DeviceFoundHandler，也就是下面贴出来的代码，

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 private class DeviceFoundHandler implements Handler {  

    public void onReceive(Context context, Intent intent,  

            BluetoothDevice device) {  

       ........................  

        // TODO Pick up UUID. They should be available for 2.1 devices.  

        // Skip for now, there's a bluez problem and we are not getting uuids even for 2.1.  

        CachedBluetoothDevice cachedDevice = mDeviceManager.findDevice(device);  

        if (cachedDevice == null) {  

            cachedDevice = mDeviceManager.addDevice(mLocalAdapter, mProfileManager, device);  

            Log.d(TAG, "DeviceFoundHandler created new CachedBluetoothDevice: "  

                    + cachedDevice);  

            // callback to UI to create Preference for new device  

            dispatchDeviceAdded(cachedDevice);  

        }  

      ......................  

    }  

}  

        在if语句中dispatchDeviceAdded()向界面分发消息，最后处理消息的地方在这里，已经到settings应用里了

   /packages/apps/Settings/src/com/android/settings/bluetooth/DeviceListPreferenceFragment.java

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public void onDeviceAdded(CachedBluetoothDevice cachedDevice) {                   

   if (mDevicePreferenceMap.get(cachedDevice) != null) {                          

       return;                                                                    

   }                                                                              

                                                                                  

   // Prevent updates while the list shows one of the state messages              

   if (mLocalAdapter.getBluetoothState() != BluetoothAdapter.STATE_ON) return;    

                                                                                  

   if (mFilter.matches(cachedDevice.getDevice())) {                               

       createDevicePreference(cachedDevice);                                      

   }                                                                              

}                     

         上面代码中最后一个分支就是界面显示要做的事了，从settings界面开始再到settings界面显示出搜索到蓝牙结束，后面的代码不再写了，本文关心的东东到此结束。

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  void createDevicePreference(CachedBluetoothDevice cachedDevice) {  

    BluetoothDevicePreference preference = new BluetoothDevicePreference(  

            getActivity(), cachedDevice);  

  

    initDevicePreference(preference);  

    mDeviceListGroup.addPreference(preference);  

    mDevicePreferenceMap.put(cachedDevice, preference);  

}  

        到目前为止，包括前面的打开流程分析，还仅是针对代码流程做的分析，对于蓝牙协议方面东西还没有涉及