Android BLE蓝牙设置为从机模式的demo

以下是一个简单的 Android BLE 蓝牙从机模式示例，可以帮助您入门：

首先，您需要在 AndroidManifest.xml 文件中添加蓝牙权限：

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

然后，在您的 Activity 中，您需要实例化 BluetoothGattServer 对象，创建一个服务和特征，并将其添加到 BluetoothGattServer 中。以下是一个简单的示例：

private BluetoothManager mBluetoothManager;
private BluetoothGattServer mGattServer;
private BluetoothGattService mGattService;
private BluetoothGattCharacteristic mGattCharacteristic;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // 初始化蓝牙管理器
    mBluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);

    // 创建从机服务
    mGattService = new BluetoothGattService(UUID.fromString("0000180d-0000-1000-8000-00805f9b34fb"),
            BluetoothGattService.SERVICE_TYPE_PRIMARY);

    // 创建从机特征
    mGattCharacteristic = new BluetoothGattCharacteristic(UUID.fromString("00002a37-0000-1000-8000-00805f9b34fb"),
            BluetoothGattCharacteristic.PROPERTY_READ | BluetoothGattCharacteristic.PROPERTY_NOTIFY,
            BluetoothGattCharacteristic.PERMISSION_READ);

    // 将特征添加到服务中
    mGattService.addCharacteristic(mGattCharacteristic);

    // 创建蓝牙从机
    mGattServer = mBluetoothManager.openGattServer(this, mGattServerCallback);

    // 将服务添加到从机
    mGattServer.addService(mGattService);
}

接下来，您需要实现 BluetoothGattServerCallback 回调函数，以处理来自中央设备的请求和通知。以下是一个简单的示例：

private BluetoothGattServerCallback mGattServerCallback = new BluetoothGattServerCallback() {
    @Override
    public void onConnectionStateChange(BluetoothDevice device, int status, int newState) {
        super.onConnectionStateChange(device, status, newState);

        // 处理连接状态变化事件
    }

    @Override
    public void onCharacteristicReadRequest(BluetoothDevice device, int requestId, int offset, BluetoothGattCharacteristic characteristic) {
        super.onCharacteristicReadRequest(device, requestId, offset, characteristic);

        // 处理读取请求
        mGattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, characteristic.getValue());
    }

    @Override
    public void onCharacteristicWriteRequest(BluetoothDevice device, int requestId, BluetoothGattCharacteristic characteristic, boolean preparedWrite, boolean responseNeeded, int offset, byte[] value) {
        super.onCharacteristicWriteRequest(device, requestId, characteristic, preparedWrite, responseNeeded, offset, value);

        // 处理写入请求
        characteristic.setValue(value);
        mGattServer.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, null);
    }

    @Override
    public void onNotificationSent(BluetoothDevice device, int status) {
        super.onNotificationSent(device, status);

        // 处理通知发送事件
    }
};

最后，您需要开始广告您的 BLE 从机服务，以便中央设备可以发现和连接到它。以下是一个简单的示例：

private BluetoothLeAdvertiser mBluetoothLeAdvertiser;

private void startAdvertising() {
    mBluetoothLeAdvertiser = BluetoothAdapter.getDefaultAdapter().getBluetoothLeAdvertiser();

    AdvertiseSettings settings = new AdvertiseSettings.Builder()
            .setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_LOW_LATENCY)
            .setConnectable(true)
            .setTimeout(0)
            .setTxPowerLevel(AdvertiseSettings.ADVERTISE_TX_POWER_HIGH)
            .build();

    AdvertiseData data = new AdvertiseData.Builder()
            .setIncludeDeviceName(true)
            .setIncludeTxPowerLevel(false)
            .addServiceUuid(new ParcelUuid(UUID.fromString("0000180d-0000-1000-8000-00805f9b34fb")))
            .build();

    mBluetoothLeAdvertiser.startAdvertising(settings, data, mAdvertiseCallback);
}

private AdvertiseCallback mAdvertiseCallback = new AdvertiseCallback() {
    @Override
    public void onStartSuccess(AdvertiseSettings settingsInEffect) {
        super.onStartSuccess(settingsInEffect);

        // 处理广告启动成功事件
    }

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

        // 处理广告启动失败事件
    }
};

这就是一个简单的 Android BLE 蓝牙从机模式示例，希望可以帮助您入门。