android - 重新连接后无法再写入 BLE 设备的特性

Question

我正在将打印数据写入 Zebra ZD410 打印机的 BluetoothGattCharacteristic。为此，我将数据分成 20 个字节的 block ，并使用以下代码一次写入一个 block :

mCharacteristic.setValue(bytes);
boolean status = mGatt.writeCharacteristic(mCharacteristic);

然后等到我收到 BluetoothGattCallback.onCharacteristicWrite()，然后再开始写入下一个 block 。这很好用。

如果我 disconnect() 和 close() BluetoothGatt 之后再次使用 BluetoothDevice.connectGatt 连接到同一设备() 然后在 onServicesDiscovered() 被调用完成后尝试写入 Characteristic 并且我再次拥有我的 Characteristic , 写入会失败。我的意思是，当我现在写入 Characteristic 时，onCharacteristicWrite() 将被调用，Characteristic 是 getValue () 返回旧 Gatt 上最后一次写入的值。

在尝试解决这个问题两天并阅读大量 SO 帖子后，我还没有找到解决方案。

我该如何解决这个问题？

编辑这是 BluetoothGattCallback

的代码

private final BluetoothGattCallback gattCallback = new BluetoothGattCallback()
{
    @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState)
    {
        FALog.i(TAG, "onConnectionStateChange Status: " + status);
        switch (newState)
        {
            case BluetoothProfile.STATE_CONNECTED:
                FALog.i(TAG, "gattCallback STATE_CONNECTED");
                gatt.discoverServices();
                break;
            case BluetoothProfile.STATE_DISCONNECTED:
                disconnectAndCloseGatt();
                mCharacteristic = null;
                connectionFailed();
                FALog.e(TAG, "gattCallback STATE_DISCONNECTED");
                break;
            default:
                FALog.e(TAG, "gattCallback STATE_OTHER");
        }
    }

    @Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status)
    {
        BluetoothGattService service = gatt.getService(PRINTER_SERVICE_UUID);
        if (service != null)
        {
            BluetoothGattCharacteristic characteristic = service.getCharacteristic
                    (PRINTER_SERVICE_CHARACTERISTIC_UUID);
            if (characteristic != null)
            {
                mCharacteristic = characteristic;
                mInternalState = STATE_CONNECTED;
                mState = State.CONNECTED;
                notifyStateChanged();
                print("~JA");
                FALog.d(TAG, "Printer connected");
                mBluetoothActivity.runOnUiThread(new Runnable()
                {
                    @Override
                    public void run()
                    {
                        mListener.onPrinterConnected();
                    }
                });
            }
        }
    }

    @Override
    public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)
    {
        FALog.d(TAG, "received onCharacteristicWrite " + new String(characteristic.getValue()) + "; success: " +
                (status == BluetoothGatt.GATT_SUCCESS));
        if (status == BluetoothGatt.GATT_SUCCESS)
        {
            handler.removeCallbacks(writeRunnable);
            popQueueAndReleaseLock();
        }
    }
};

Answer 1

在 onDescriptorWrite() 回调之后尝试 writeCharacteristic 而不是 onServicesDiscovered() 回调。 writeDescriptor 持有 mDeviceBusy。