Android 蓝牙通信

news2025/6/8 5:10:59

Android 平台提供了完整的蓝牙 API，支持

传统蓝牙(Bluetooth Classic)和低功耗蓝牙(BBluetooth Low Energy, BLE)两种通信方式。

以下是开发蓝牙应用的关键知识点。

1. 基本概念

传统蓝牙(Bluetooth Classic)

适合大流量数据传输(如音频、文件传输)
典型协议: RFCOMM(串口模拟), A2DP(音频), HFP(免提)等

低功耗蓝牙(BLE)

适合间歇性小数据量传输，功耗低
典型应用: 健康设备、传感器、信标(Beacon)

2. 开发准备

清单文件配置

<!-- 蓝牙权限 -->
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

<!-- 蓝牙扫描需要的位置权限(Android 6.0+) -->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

<!-- 仅用于Android 12+ -->
<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />

<!-- 声明蓝牙功能 -->
<uses-feature android:name="android.hardware.bluetooth" android:required="true" />

运行时权限请求(Android 6.0+)

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) 
        != PackageManager.PERMISSION_GRANTED) {
        requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 
            REQUEST_LOCATION_PERMISSION);
    }
}

3. 传统蓝牙开发

检查并启用蓝牙

BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

// 检查设备是否支持蓝牙
if (bluetoothAdapter == null) {
    // 设备不支持蓝牙
    return;
}

// 检查蓝牙是否启用，如果未启用则请求启用
if (!bluetoothAdapter.isEnabled()) {
    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}

发现设备

// 注册广播接收器监听发现的设备
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(receiver, filter);

// 开始发现设备
bluetoothAdapter.startDiscovery();

// 广播接收器示例
private final BroadcastReceiver receiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (BluetoothDevice.ACTION_FOUND.equals(action)) {
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            String deviceName = device.getName();
            String deviceAddress = device.getAddress();
            // 处理发现的设备
        }
    }
};

// 停止发现
bluetoothAdapter.cancelDiscovery();

客户端连接(作为客户端)

// 假设已获取到BluetoothDevice对象
BluetoothDevice device = ...;

// 使用UUID创建RFCOMM连接
UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); // 标准串口UUID
BluetoothSocket socket = device.createRfcommSocketToServiceRecord(uuid);

// 连接
try {
    socket.connect();
    // 连接成功，获取输入输出流
    InputStream inputStream = socket.getInputStream();
    OutputStream outputStream = socket.getOutputStream();
    
    // 进行数据读写
    outputStream.write("Hello".getBytes());
    byte[] buffer = new byte[1024];
    int bytes = inputStream.read(buffer);
    
} catch (IOException e) {
    e.printStackTrace();
} finally {
    socket.close();
}

服务端监听(作为服务端)

// 创建监听socket
BluetoothServerSocket serverSocket = bluetoothAdapter.listenUsingRfcommWithServiceRecord(
    "MyBluetoothApp", uuid);

// 接受连接(应在后台线程执行)
try {
    BluetoothSocket socket = serverSocket.accept();
    // 连接建立，处理通信
    InputStream inputStream = socket.getInputStream();
    OutputStream outputStream = socket.getOutputStream();
    
    // 通信处理...
    
} catch (IOException e) {
    e.printStackTrace();
} finally {
    serverSocket.close();
}

4. 低功耗蓝牙(BLE)开发

初始化BLE

BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
BluetoothAdapter bluetoothAdapter = bluetoothManager.getAdapter();

// 检查BLE支持
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
    // 设备不支持BLE
    return;
}

// 启用蓝牙(同传统蓝牙)

扫描BLE设备

// BLE扫描回调
private ScanCallback scanCallback = new ScanCallback() {
    @Override
    public void onScanResult(int callbackType, ScanResult result) {
        BluetoothDevice device = result.getDevice();
        String deviceName = device.getName();
        String deviceAddress = device.getAddress();
        // 处理发现的设备
    }
};

// 开始扫描
BluetoothLeScanner scanner = bluetoothAdapter.getBluetoothLeScanner();
List<ScanFilter> filters = new ArrayList<>(); // 可选过滤条件
ScanSettings settings = new ScanSettings.Builder()
    .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
    .build();
scanner.startScan(filters, settings, scanCallback);

// 停止扫描
scanner.stopScan(scanCallback);

连接BLE设备

// 蓝牙GATT回调
private BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        if (newState == BluetoothProfile.STATE_CONNECTED) {
            // 连接成功，发现服务
            gatt.discoverServices();
        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
            // 连接断开
        }
    }
    
    @Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status) {
        if (status == BluetoothGatt.GATT_SUCCESS) {
            // 服务发现完成，可以读写特征值
            List<BluetoothGattService> services = gatt.getServices();
            for (BluetoothGattService service : services) {
                List<BluetoothGattCharacteristic> characteristics = 
                    service.getCharacteristics();
                // 处理特征值
            }
        }
    }
    
    @Override
    public void onCharacteristicRead(BluetoothGatt gatt, 
            BluetoothGattCharacteristic characteristic, int status) {
        // 特征值读取完成
        byte[] data = characteristic.getValue();
    }
    
    @Override
    public void onCharacteristicWrite(BluetoothGatt gatt, 
            BluetoothGattCharacteristic characteristic, int status) {
        // 特征值写入完成
    }
    
    @Override
    public void onCharacteristicChanged(BluetoothGatt gatt, 
            BluetoothGattCharacteristic characteristic) {
        // 特征值通知数据到达
        byte[] data = characteristic.getValue();
    }
};

// 连接设备
BluetoothDevice device = ...; // 从扫描结果获取
BluetoothGatt gatt = device.connectGatt(context, false, gattCallback);

// 断开连接
gatt.disconnect();
gatt.close();

读写BLE特征值

// 获取特征值对象(通常在onServicesDiscovered回调中)
BluetoothGattCharacteristic characteristic = ...;

// 读取特征值
gatt.readCharacteristic(characteristic);

// 写入特征值
characteristic.setValue("Hello".getBytes());
gatt.writeCharacteristic(characteristic);

// 启用通知
gatt.setCharacteristicNotification(characteristic, true);
BluetoothGattDescriptor descriptor = characteristic.getDescriptor(
    UUID.fromString("00002902-0000-1000-8000-00805f9b34fb")); // 客户端特征配置描述符
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
gatt.writeDescriptor(descriptor);