Android BLE Client端发起连接，并完成配对

要在Android BLE Client端发起连接并完成配对，需要遵循以下步骤：

1. 获取BluetoothAdapter对象并确保蓝牙已启用。

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (!mBluetoothAdapter.isEnabled()) {
    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}

2. 扫描BLE设备并获取设备列表。

private final List<BluetoothDevice> mDevices = new ArrayList<>();
private final BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {
            @Override
            public void onLeScan(final BluetoothDevice device, final int rssi, final byte[] scanRecord) {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        if (!mDevices.contains(device)) {
                            mDevices.add(device);
                            mDeviceListAdapter.notifyDataSetChanged();
                        }
                    }
                });
            }
        };
mBluetoothAdapter.startLeScan(mLeScanCallback);

3. 停止扫描并选择要连接的设备。

mBluetoothAdapter.stopLeScan(mLeScanCallback);
BluetoothDevice device = mDevices.get(position);

4. 从设备中获取Gatt服务并连接。

BluetoothGatt gatt = device.connectGatt(this, false, mGattCallback);

5. 处理Gatt连接状态。

private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
        if (newState == BluetoothProfile.STATE_CONNECTED) {
            gatt.discoverServices();
        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
            // 处理断开连接的情况
        }
    }
};

6. 在Gatt服务中查找服务和特征。

@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
    if (status == BluetoothGatt.GATT_SUCCESS) {
        BluetoothGattService service = gatt.getService(SERVICE_UUID);
        BluetoothGattCharacteristic characteristic = service.getCharacteristic(CHARACTERISTIC_UUID);
        gatt.setCharacteristicNotification(characteristic, true);
    } else {
        // 处理服务发现失败的情况
    }
}

7. 连接到设备并请求配对。

BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(deviceAddress);
device.createBond();

8. 处理配对结果。

private final BroadcastReceiver mPairingRequestReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (BluetoothDevice.ACTION_PAIRING_REQUEST.equals(action)) {
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            int variant = intent.getIntExtra(BluetoothDevice.EXTRA_PAIRING_VARIANT, BluetoothDevice.ERROR);
            if (variant == BluetoothDevice.PAIRING_VARIANT_PIN) {
                byte[] pin = "1234".getBytes();
                device.setPin(pin);
            }
        }
    }
};