一、前言
截止到本文完成的日期为止（04月16日），笔者对Android 5.0~Android 10的部分手机进行了适配测试。该文中所遇到的问题基本都出现在国产定制系统（EMUI、MIUI、ColorOS）上。开发环境为macOS+idea。
二、相关代码
<uses-permission android:name="android.permission.BLUETOOTH" /><uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /><uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /><uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /><uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" /><uses-featureandroid:name="android.hardware.bluetooth_le"android:required="true" />
*BLE的扫描需要开启位置信息相关的权限，否则将会无法扫描到BLE设备。
*在MIUI11（Android 10）中，需要另行打开位置服务（GPS），否则也不能扫描到BLE设备。部分其它国产ROM在Android 10也可能存在此问题，解决办法同上。判断标准是：BluetoothLeScanner被正确地实例化（不为null），但始终无法发现附近的BLE设备。
2、（Android 6.0及以上）在onCreate中动态申请位置信息权限：
if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {Log.i(TAG, "sdk < Android M");if (ActivityCompat.checkSelfPermission(this,Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED|| ActivityCompat.checkSelfPermission(this,Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {String[] strings ={Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION};ActivityCompat.requestPermissions(this, strings, 1);}} else {if (ActivityCompat.checkSelfPermission(this,Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED|| ActivityCompat.checkSelfPermission(this,Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED|| ActivityCompat.checkSelfPermission(this,"android.permission.ACCESS_BACKGROUND_LOCATION") != PackageManager.PERMISSION_GRANTED) {String[] strings = {android.Manifest.permission.ACCESS_FINE_LOCATION,android.Manifest.permission.ACCESS_COARSE_LOCATION,"android.permission.ACCESS_BACKGROUND_LOCATION"};ActivityCompat.requestPermissions(this, strings, 2);}}
检测是否打开位置服务：
public static final boolean isLocationEnable(Context context) {LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);boolean networkProvider = locationManager.isProviderEnabled(WORK_PROVIDER);boolean gpsProvider = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);if (networkProvider || gpsProvider) return true;return false;}
如果未打开位置服务，让用户去打开：
private static final int REQUEST_CODE_LOCATION_SETTINGS = 2;private void setLocationService() {Intent locationIntent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);this.startActivityForResult(locationIntent, REQUEST_CODE_LOCATION_SETTINGS);}
进入设置，让用户自己选择是否打开位置服务，然后获取选择结果：
@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {if (requestCode == REQUEST_CODE_LOCATION_SETTINGS) {if (isLocationEnable(this)) {//定位已打开的处理} else {//定位依然没有打开的处理}} else super.onActivityResult(requestCode, resultCode, data);}
3、（基本）检测是否支持BLE蓝牙及蓝牙开关状态
//是否支持public static boolean isSupportBle(Context context) {if (context == null || !context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {return false;}BluetoothManager manager = (BluetoothManager) context.getSystemService(Context.BLUETOOTH_SERVICE);return manager.getAdapter() != null;}//是否开启public static boolean isBleEnable(Context context) {if (!isSupportBle(context)) {return false;}BluetoothManager manager = (BluetoothManager) context.getSystemService(Context.BLUETOOTH_SERVICE);return manager.getAdapter().isEnabled();}//开启蓝牙public static void enableBluetooth(Activity activity, int requestCode) {Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);activity.startActivityForResult(intent, requestCode);}
4、（基本&&Android 7.0+适配特别注意！）进行BLE设备扫描
在Android 7.0及以后的系统中，BluetoothAdapter.startLeScan()方法被废弃，所以需要根据系统版本的不同来执行不同的扫描方法，否则在MIUI11及EMUI10的部分机型上会扫描不到BLE设备。
private void startScan() throws Exception {isScanning = true;handler.postDelayed(scanRunnable, TIME_OUT);BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {LogUtil.e("系统版本：","<7.0");bluetoothManager.getAdapter().startLeScan(mLeScanCallback);} else {//安卓7.0及以上的方案LogUtil.e("系统版本：",">=7.0");bleScanner = bluetoothManager.getAdapter().getBluetoothLeScanner();bleScanner.startScan(scanCallback);}}
//停止扫描private void stopScan() {isScanning = false;BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {//安卓6.0及以下版本BLE操作的代码bluetoothManager.getAdapter().stopLeScan(mLeScanCallback);} else//安卓7.0及以上版本BLE操作的代码bleScanner.stopScan(scanCallback);}
//扫描结果回调-Android 7.0-private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {@SuppressLint("HandlerLeak")@Overridepublic void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {LogUtil.e(TAG, "开始搜索设备：" + mac);if (device.getAddress().equals(mac)) {LogUtil.e(TAG, "搜索到设备 " + mac);new Handler() {@Overridepublic void handleMessage(Message msg) {if (mBluetoothLeService != null) {mBluetoothLeService.connect(mac);}}}.sendEmptyMessageDelayed(3000, 200);stopScan();isScanning = false;handler.removeCallbacks(scanRunnable);}}};//扫描结果回调-7.0+private ScanCallback scanCallback = new ScanCallback() {@SuppressLint("HandlerLeak")@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)@Overridepublic void onScanResult(int callbackType, ScanResult result) {super.onScanResult(callbackType, result);BluetoothDevice device = result.getDevice();String macAddr = device.getAddress();LogUtil.e("发现设备：", macAddr);if (macAddr.equals(mac)) {LogUtil.e(TAG, "搜索到匹配的蓝牙设备(6.0+): " + mac);new Handler() {@Overridepublic void handleMessage(Message msg) {if (mBluetoothLeService != null) {mBluetoothLeService.connect(mac);}}}.sendEmptyMessageDelayed(3000, 200);stopScan();isScanning = false;handler.removeCallbacks(scanRunnable);}Log.i(TAG, macAddr);}};
//重连计时器private Runnable scanRunnable = new Runnable() {@Overridepublic void run() {connTimeOutTimes++;LogUtil.e(TAG, "重连第" + connTimeOutTimes + "次");if (connTimeOutTimes < RECONNECT_TIMES) {handler.postDelayed(scanRunnable, TIME_OUT);} else {stopScan();connTimeOutTimes = 0;if (connectFunction != null) {LogUtil.e(TAG, "连接超时：" + mBluetoothLeService.getConnectState());connectFunction.onCallBack("{\"code\":-1,\"msg\":\"连接超时\",\"data\":\"false\"}");connectFunction = null;}if (cardConnectFunction != null) {cardConnectFunction.onCallBack("{\"code\":-1,\"msg\":\"连接超时\",\"data\":\"false\"}");cardConnectFunction = null;}mBluetoothLeService.setConnectionState(0);mBluetoothLeService.release();bindStatus = 0;}}};
三、踩过坑的机型/ROM
1、小米/红米
MIUI11：必须打开位置服务才可搜索到BLE设备；
MIUI11及更早：
初始化BlueToothGatt时务必将connectGatt的autoConnect设为false，否则会被系统杀掉；
package android.bluetooth;public final class BluetoothDevice implements Parcelable {...public BluetoothGatt connectGatt(Context context, boolean autoConnect,BluetoothGattCallback callback) {return (connectGatt(context, autoConnect, callback, TRANSPORT_AUTO));}}
必须针对Android M及以上的MIUI配置调用BluetoothLeScanner.startScan()方法来搜索BLE设备，而非被废弃的BluetoothAdapter.startLeScan()，否则将无法搜索到设备，日志如下：
D/BluetoothAdapter: startLeScan(): null**注意，此处为nullD/BluetoothAdapter: isLeEnabled(): OND/BluetoothLeScanner: onScannerRegistered() - status=0 scannerId=6 mScannerId=0
2、华为/荣耀
EMUI10（仅Mate 30/P30系列）：必须打开位置服务才可搜索到BLE设备
3、部分国产ROM（包括上述两类）：
部分机型需打开位置服务才可搜索到BLE设备；
部分机型需动态申请位置权限才可搜索到BLE设备；
部分机型需将connectGatt的autoConnect设为false（MIUI、ColorOS）；
部分机型需针对Android M及以上的系统版本配置调用BluetoothLeScanner.startScan()方法来搜索BLE设备；
四、附录：连接日志（MIUI）
E/系统版本：: >=6.0D/BluetoothAdapter: isLeEnabled(): OND/BluetoothLeScanner: onScannerRegistered() - status=0 scannerId=8 mScannerId=0E/发现设备：: xx:xx:xx:xx:xx:xxE/WebViewActivity: 搜索到匹配的蓝牙设备(6.0+): xx:xx:xx:xx:xx:xxD/BluetoothAdapter: isLeEnabled(): ONI/WebViewActivity: xx:xx:xx:xx:xx:xxE/BlueToothService: xx:xx:xx:xx:xx:xxD/BluetoothGatt: onClientConnectionState() - status=0 clientIf=7 device=xx:xx:xx:xx:xx:xxD/BluetoothGatt: discoverServices() - device: xx:xx:xx:xx:xx:xxE/WebViewActivity: 连接成功：2D/BluetoothGatt: onConnectionUpdated() - Device=xx:xx:xx:xx:xx:xx interval=6 latency=0 timeout=500 status=0D/BluetoothGatt: onSearchComplete() = Device=xx:xx:xx:xx:xx:xx Status=0D/BluetoothGatt: setCharacteristicNotification() - uuid: 0000fff4-xxxx-xxxx-xxxx-00xxxx9bxxxx enable: trueD/BluetoothGatt: onConnectionUpdated() - Device=xx:xx:xx:xx:xx:xx interval=36 latency=0 timeout=500 status=0
完！！！
