Android BLE蓝牙通信

为了在app中使用蓝牙功能，必须声明蓝牙权限BLUETOOTH。利用这个权限去执行蓝牙通信，例如请求连接、接受连接、和传输数据。如果想让你的app启动设备发现或操纵蓝牙设置，必须声明BLUETOOTH_ADMIN权限。
在AndroidManifest.xml文件中添加权限：

<uses-permission android:name="android.permission.BLUETOOTH" /><uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

如果想声明你的app只为具有BLE的设备提供，还需要声明uses-feature：

<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>

当required为true时，应用只能在支持BLE的Android设备上安装运行；required为false时，Android设备均可正常安装运行，需要在代码运行时判断设备是否支持BLE feature：

// 使用此检查确定BLE是否支持在设备上，然后你可以有选择性禁用BLE相关的功能if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {    Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();    finish();}

初始化：

@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    // 初始化蓝牙适配器    final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);    mBluetoothAdapter = bluetoothManager.getAdapter();    judgeBluetoothEnable();}

//判断蓝牙状态private void judgeBluetoothEnable() {    if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {        enableBt = false;        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);    } else {        enableBt = true;        mBluetoothLeScanner = mBluetoothAdapter.getBluetoothLeScanner();    }}

private static final ParcelUuid SAMPLE_UUID = new ParcelUuid(UUID.fromString("6e400000-b5a3-f393-e0a9-e50e24dcca9c"));//private static final String DEVICE_NAME_STRING = "LeShoe01";//搜索蓝牙设备private void scanLeDevice(final boolean enable) {    if (enable) {        mScanning = true;        List<ScanFilter> bleScanFilters = new ArrayList<>();        //添加过滤规则        bleScanFilters.add(new ScanFilter.Builder().setServiceUuid(SAMPLE_UUID).build());//      bleScanFilters.add(new ScanFilter.Builder().setDeviceName(DEVICE_NAME_STRING).build());        ScanSettings bleScanSettings = new ScanSettings.Builder().build();        Log.d(TAG, "Starting scanning with settings:" + bleScanSettings + " and filters:" + bleScanFilters);        //开始搜索        mBluetoothLeScanner.startScan(bleScanFilters, bleScanSettings, mScanCallback);    } else {        mScanning = false;        stopScanning();    }}//停止搜索private void stopScanning() {    if (mBluetoothLeScanner != null) {        Log.d(TAG, "Stop scanning.");        mBluetoothLeScanner.stopScan(mScanCallback);    }}//BLE设备搜索回调private ScanCallback mScanCallback = new ScanCallback() {    @Override    public void onScanResult(int callbackType, ScanResult result) {        //结果返回        BluetoothDevice device = result.getDevice();    }};

//连接设备mBluetoothGatt = device.connectGatt(this, false, mGattCallback);BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {    @Override    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {        if (newState == BluetoothProfile.STATE_CONNECTED) {// 当蓝牙设备已经连接            Log.i(TAG, "Connected to GATT server.");            gatt.discoverServices();        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {// 当设备无法连接            Log.e(TAG, "Disconnected from GATT server !");        }    }    //发现服务    @Override    public void onServicesDiscovered(BluetoothGatt gatt, int status) {        if (status == BluetoothGatt.GATT_SUCCESS) {            Log.i(TAG, "onServicesDiscovered GATT_SUCCESS");            BluetoothGattService service = gatt.getService(UUID.fromString("6e400000-b5a3-f393-e0a9-e50e24dcca9c"));            Txcharacteristic = service.getCharacteristic(UUID.fromString("6e400002-b5a3-f393-e0a9-e50e24dcca9c"));            Rxcharacteristic = service.getCharacteristic(UUID.fromString("6e400003-b5a3-f393-e0a9-e50e24dcca9c"));            //接收通知            gatt.setCharacteristicNotification(Rxcharacteristic, true);            //发送数据            Txcharacteristic.setValue(new byte[]{0x3b});            gatt.writeCharacteristic(Txcharacteristic);        } else {            Log.e(TAG, "onServicesDiscovered status: " + status);        }    }    //收到通知    @Override    public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {        Log.i(TAG, "---------- onCharacteristicChanged ----------");        //获取数据        byte[] result = characteristic.getValue();        StringBuilder sb = new StringBuilder();        String hv = null;        for (byte b : result) {            hv = Integer.toHexString(b & 0xFF);            if (hv.length() < 2) {                sb.append(0);            }            sb.append(hv);        }        Log.i(TAG, "onCharacteristicChanged characteristic.getValue(): " + sb.toString());    }};