使用 Gatt 伺服器

為了讓你的裝置充當外圍裝置，首先你需要開啟一個 BluetoothGattServer 並用至少一個 BluetoothGattService 和一個 BluetoothGattCharacteristic 填充它：

BluetoothGattServer server=bluetoothManager.openGattServer(context, bluetoothGattServerCallback);

BluetoothGattService service = new BluetoothGattService(SERVICE_UUID, BluetoothGattService.SERVICE_TYPE_PRIMARY);

這是具有完全寫入，讀取和通知許可權的 BluetoothGattCharacteristic 的示例。根據你的需要，你可能希望微調授予此特性的許可權：

BluetoothGattCharacteristic characteristic = new BluetoothGattCharacteristic(CHARACTERISTIC_UUID,
                    BluetoothGattCharacteristic.PROPERTY_READ | BluetoothGattCharacteristic.PROPERTY_WRITE |
                            BluetoothGattCharacteristic.PROPERTY_NOTIFY,
                    BluetoothGattCharacteristic.PERMISSION_READ | BluetoothGattCharacteristic.PERMISSION_WRITE);

characteristic.addDescriptor(new BluetoothGattDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"), BluetoothGattCharacteristic.PERMISSION_WRITE));

service.addCharacteristic(characteristic);

server.addService(service);

BluetoothGattServerCallback 負責接收與你的 BluetoothGattServer 相關的所有事件：

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

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

                @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);
                }

                @Override
                public void onDescriptorReadRequest(BluetoothDevice device, int requestId, int offset, BluetoothGattDescriptor descriptor) {
                    super.onDescriptorReadRequest(device, requestId, offset, descriptor);
                }

                @Override
                public void onDescriptorWriteRequest(BluetoothDevice device, int requestId, BluetoothGattDescriptor descriptor, boolean preparedWrite, boolean responseNeeded, int offset, byte[] value) {
                    super.onDescriptorWriteRequest(device, requestId, descriptor, preparedWrite, responseNeeded, offset, value);
                }

每當你收到對特徵或描述符的寫入/讀取請求時，你必須向其傳送響應，以便成功完成請求：

@Override
 public void onCharacteristicReadRequest(BluetoothDevice device, int requestId, int offset, BluetoothGattCharacteristic characteristic) {
    super.onCharacteristicReadRequest(device, requestId, offset, characteristic);
    server.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, YOUR_RESPONSE);
}