android -- 蓝牙 bluetooth (三)搜索蓝牙
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接上篇打开蓝牙继续,来一起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
private void updateContent(int bluetoothState, boolean scanState) { if (numberOfPairedDevices == 0) { preferenceScreen.removePreference(mPairedDevicesCategory); if (scanState == true) { mActivityStarted = false; startScanning(); } else ........} 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
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
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,
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
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
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。
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; }
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
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 : 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
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
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
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,
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,
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
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。
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,比如蓝牙是如何发现其它蓝牙设备,这个流程究竟是怎么工作还不是很清楚,后续会尽量关注这些问题,估计看起来就没那么容易,欢迎有经验的朋友指点一二,当然对于本文不足,欢迎拍砖讨论。分享是快乐的,谢谢!
--------------modify 2013.6.2 21:08--------
更新蓝牙搜索返回后的跳转代码
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