Android 蓝牙开发

我们在进行蓝牙开发时首先要了解低功耗蓝牙、经典蓝牙、单模蓝牙、双模蓝牙之间的关系。
单模蓝牙：支持低功耗蓝牙
双模蓝牙：支持低功耗蓝牙和经典蓝牙
经典蓝牙：支持经典蓝牙
蓝牙开发大致分为这几步

前面需要定位权限和蓝牙权限的支持

发现设备：

经典蓝牙发现设备api
BluetoothAdapter.startDiscovery
听说可以同时发现经典蓝牙和低功耗蓝牙(BLE)。但我这没单模的蓝牙，所以没办法测试。
因为startDiscovery返回的是一个是否开始扫描设备，我们要获取蓝牙设备的信息需要注册一个 BroadcastReceiver 针对 ACTION_FOUND
Intent 会携带额外的字段 EXTRA_DEVICE 和 EXTRA_CLASS。这两者分别包含 BluetoothDevice 和 BluetoothClass。

var filter =IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver,filter);
    
    val mReceiver = object :BroadcastReceiver(){
        override fun onReceive(context: Context?, intent: Intent?) {
            var action = intent?.action
            if(BluetoothDevice.ACTION_FOUND == action){
                var device = intent?.getParcelableExtra<BluetoothDevice>(BluetoothDevice.EXTRA_DEVICE)
            }
        }

    }
    override fun onDestroy() {
        super.onDestroy()
        unregisterReceiver(mReceiver)
    }

Ble发现设备api
BluetoothAdapter.getBluetoothLeScanner()
BluetoothLeScanner.startScan(ScanCallback callback)//扫描会在屏幕关闭时停止以节省电量。再次打开屏幕时，将恢复扫描。为避免这种情况，请使用下面两个
BluetoothLeScanner.startScan(List<ScanFilter> filters, ScanSettings settings, ScanCallback callback)
BluetoothLeScanner.startScan(List<ScanFilter> filters, ScanSettings settings, PendingIntent callbackIntent)

BluetoothLeScanner bluetoothLeScanner = bluetoothAdapter.getBluetoothLeScanner();
        filters.add(new ScanFilter.Builder()
                .setServiceUuid(ParcelUuid.fromString("0000000-0000-0000-0000-000000000000"))
                .build());
        bluetoothLeScanner.startScan(filters , new ScanSettings.Builder().build(),
                new ScanCallback() {
                    @Override
                    public void onScanResult(int callbackType, ScanResult result) {
                        super.onScanResult(callbackType, result);
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                            Log.d(MainActivity.ACTIVITY_SERVICE, "onScanResult:"+
                                "\n Rssi() "+result.getRssi()+
                                "\n AdvertisingSid() "+result.getAdvertisingSid()+
                                "\n DataStatus() "+result.getDataStatus()+
                                "\n ScanRecord() "+result.getScanRecord().getBytes()+
                                "\n Address() "+result.getDevice().getAddress()+
                                "\n Address() "+result.getDevice().getName()
                                );
                        }
                    }

                    @Override
                    public void onBatchScanResults(List<ScanResult> results) {
                        super.onBatchScanResults(results);
                    }

                    @Override
                    public void onScanFailed(int errorCode) {
                        super.onScanFailed(errorCode);
                    }
                }
        );

建立连接:

在配对之前应该先cancelDiscovery()或者stopScan(callback)，
然后根据获取到蓝牙Mac地址连接即可

BluetoothDevice device = bluetoothAdapter.getRemoteDevice(result.getDevice().getAddress());
device.connectGatt(MainActivity.this, false, new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
            super.onConnectionStateChange(gatt, status, newState);
            //status 连接或断开连接操作成功 BluetoothGatt.GATT_SUCCESS(0)
            //newState 新的连接状态 BluetoothProfile.STATE_DISCONNECTED(0-断开状态) BluetoothProfile.STATE_CONNECTED(1-连接状态)
        }
    }
);

数据通信:
ble写入操作

 private BluetoothGattCallback bluetoothGattCallback = new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
            super.onConnectionStateChange(gatt, status, newState);
            //status 连接或断开连接操作成功 BluetoothGatt.GATT_SUCCESS(0)
            //newState 新的连接状态 BluetoothProfile.STATE_DISCONNECTED(0-断开状态) BluetoothProfile.STATE_CONNECTED(1-连接状态)
            //获取远程设备提供的服务以及它们的特征和描述符。这步很重要而且是一个异步操作（这里需要时间直接接在下面写不可取）
            bluetoothGatt.discoverServices();
            //获取蓝牙GATT服务
            BluetoothGattService gattService = bluetoothGatt.getService(UUID.fromString("00000000-0000-0000-0000-000000000000"/*蓝牙协议*/));
            //GATT特性：用于构建 GATT 服务的基本数据元素
            BluetoothGattCharacteristic characteristic = gattService.getCharacteristic(UUID.fromString("00000000-0000-0000-0000-000000000000"));
            //设置数据，这里是我加密后的数据所以看起来有点不习惯
            byte[] data = {-27, 36, 65, -70, -8, 94, 18, -12, -56, 116, -68, -124, 92, -19, 94, -91 };
            //设置此特性的本地存储值。
            characteristic.setValue(data);
            //写入到远程蓝牙设备
            bluetoothGatt.writeCharacteristic(characteristic);
                  
      

        }

Ble通知读取操作

//通知UUID
BluetoothGattCharacteristic gattCharacteristic = gattService.getCharacteristic(UUID.fromString("00000000-0000-0000-0000-000000000000"));
enableNotification(bluetoothGatt,true,gattCharacteristic);

public void enableNotification(BluetoothGatt bluetoothGatt, boolean enable, BluetoothGattCharacteristic characteristic) {
            if (bluetoothGatt == null || characteristic == null) {
                return;
            }
            if (!bluetoothGatt.setCharacteristicNotification(characteristic, enable)) {
                return;
            }
            //获取到Notify当中的Descriptor通道  然后再进行注册
            List<BluetoothGattDescriptor> clientConfigs = characteristic.getDescriptors();
            if (clientConfigs == null || clientConfigs.size() ==0) {
                return;
            }
            if (enable) {
                for (BluetoothGattDescriptor clientConfig: clientConfigs) {
                    clientConfig.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
                    bluetoothGatt.writeDescriptor(clientConfig);
                }
            } else {
                for (BluetoothGattDescriptor clientConfig: clientConfigs) {
                    clientConfig.setValue(BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE);
                    bluetoothGatt.writeDescriptor(clientConfig);
                }
            }
        }