Question

我正在编写一个与BLE仪表通话的Android应用程序。我已经能够扫描设备，连接到目标，发现服务并获得特征。但是，当我尝试编写write_no_reponse特性时，该方法始终返回false。我确信特性是可写的，我使用其他应用程序来做到这一点。当我调试到android.bluetooth代码时，以下序列发生故障，可能返回空服务，调试运行到这一步，然后退出该方法：

BluetoothGattService service = characteristic.getService();

导致writeCharacteristic返回false。但是在writeCharacteristic之前，我有一个日志

Log.d(TAG, "onServicesDiscovered: writeType" + mCharacteristic.getService());
bluetoothGatt.writeCharacteristic(mCharacteristic);

并且日志正确，并且不返回null；

非常感谢您的帮助！

而且我使用相同的代码来写WRITE特征，它起作用了。我尝试使用

mCharacteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);

设置写入类型，但也失败。

写入数据代码：

public void writeReadDataCommand() {
    if (null != bluetoothGatt) {
        mCharacteristic.setValue("123123");
        bluetoothGatt.setCharacteristicNotification(mCharacteristic, true);
        mCharacteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
        Log.d(TAG, "onServicesDiscovered: writeType" + mCharacteristic.getService());
        boolean isWrite = bluetoothGatt.writeCharacteristic(mCharacteristic);
        if (isWrite) {
            Log.d(TAG, "writeReadDataCommand: write data to BLE");
        }
    }
}

onServiceDiscovered代码：

@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
    super.onServicesDiscovered(gatt, status);

    if (status == BluetoothGatt.GATT_SUCCESS) {
        bluetoothGatt = gatt;
        BluetoothGattService service = gatt.getService(UUID.fromString(SERVICE_UUID));
        BluetoothGattCharacteristic characteristic = service.getCharacteristic(UUID.fromString(CHARACTERISTIC_UUID));
        Log.d(TAG, "onServicesDiscovered: writeType" + characteristic.getWriteType());

        boolean isSuccess = gatt.setCharacteristicNotification(characteristic, true);
        if (isSuccess) {
            mCharacteristic = characteristic;
            List<BluetoothGattDescriptor> descriptors = characteristic.getDescriptors();
            if (null != descriptors && descriptors.size() > 0) {
                for (BluetoothGattDescriptor descriptor : descriptors) {
                    descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
                    gatt.writeDescriptor(descriptor);
                }
            }
        }
        connectCallback.findService();
    } else {
        Log.d(TAG, "onServicesDiscovered received: " + status);
    }
}

并且onCharacteristicWrite回调不会触发

public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
    Log.d(TAG, "onCharacteristicWrite: " + Arrays.toString(characteristic.getValue()));
}

我很久没有这个bug了，非常感谢有人帮忙。

Answer 1

characteristics

如图所示，我在服务中有2个特征-0和1。这些特征具有相同的uuid。我首先要做的是

BluetoothGattCharacteristic characteristic = service.getCharacteristic(UUID.fromString(CHARACTERISTIC_UUID));

这段代码找到0特征，然后我向它写入数据。很明显，我失败了。因为0特性只能读取和通知。因此，我按照以下步骤将日期写入BLE

                characteristics = service.getCharacteristics();
                for(BluetoothGattCharacteristic characteristic : characteristics){
                    if(characteristic.getUuid().equals(UUID.fromString(CHARACTERISTIC_UUID))){
                        enableNotification(characteristic);
                    }
                }

            for(BluetoothGattCharacteristic characteristic : characteristics){
                if(characteristic.getUuid().equals(UUID.fromString(CHARACTERISTIC_UUID))){
                    characteristic.setValue("123123");
                    characteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);

                    boolean isWrite = bluetoothGatt.writeCharacteristic(characteristic);
                    if (isWrite) {
                        Log.d(TAG, "writeReadDataCommand: write data to ble");
                    }
                }
            }

我尝试通知这两个特征并将数据写入这两个特征，尽管它们具有相同的UUID，但它们具有不同的功能。显然，一个特征将通知失败，一个特征将写入失败。但最后我成功写入了数据。

Answer 2

在 onDescriptorWrite() 将数据发送到 BLE 设备之后。

 private final BluetoothGattCallback getGattCallback1=new BluetoothGattCallback() {
        @Override
        public void onPhyUpdate(BluetoothGatt gatt, int txPhy, int rxPhy, int status) {
            super.onPhyUpdate(gatt, txPhy, rxPhy, status);
        }

        @Override
        public void onPhyRead(BluetoothGatt gatt, int txPhy, int rxPhy, int status) {
            super.onPhyRead(gatt, txPhy, rxPhy, status);
        }

        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
            super.onConnectionStateChange(gatt, status, newState);
        }

        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            super.onServicesDiscovered(gatt, status);
        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            super.onCharacteristicRead(gatt, characteristic, status);
        }

        @Override
        public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            super.onCharacteristicWrite(gatt, characteristic, status);
        }

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
            super.onCharacteristicChanged(gatt, characteristic);
        }

        @Override
        public void onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
            super.onDescriptorRead(gatt, descriptor, status);
        }

        @Override
        public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
            super.onDescriptorWrite(gatt, descriptor, status);
            // here send broadcast to MainActivity.That u are ready to write Data To the device.
        }

        @Override
        public void onReliableWriteCompleted(BluetoothGatt gatt, int status) {
            super.onReliableWriteCompleted(gatt, status);
        }

        @Override
        public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status) {
            super.onReadRemoteRssi(gatt, rssi, status);
        }

        @Override
        public void onMtuChanged(BluetoothGatt gatt, int mtu, int status) {
            super.onMtuChanged(gatt, mtu, status);
        }
    };

 @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    public void setCharacteristicNotifications(BluetoothGatt bluetoothGatt,BluetoothGattCharacteristic characteristic,
                                               boolean enabled,String bleAddress) {
        if (mBluetoothAdapter == null || bluetoothGatt == null) {
            return;
        }
        bluetoothGatt.setCharacteristicNotification(characteristic, enabled);
        BluetoothGattDescriptor descriptor = null;
        descriptor = characteristic.getDescriptor(UUID.fromString(CLIENT_CHARACTERISTIC_CONFIG));
        if (descriptor == null) {
            enableNotiticationToFirmwareCompleted(false,bleAddress);
            return;
        }
        descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
        bluetoothGatt.writeDescriptor(descriptor);

     }

bluetoothGatt.writeCharacteristic始终返回false，并且ble特征类型为write_no_reponse

2 个答案: