reactive_flutter_BLE 应用找到设备但无法连接(并读取 BLE 数据)

第一个代码，可以编译，但不能按预期工作:

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_reactive_ble/flutter_reactive_ble.dart';
import 'package:location_permissions/location_permissions.dart';


class BluetoothConnectionScreen extends StatefulWidget {
  const BluetoothConnectionScreen({super.key});

  @override
  State<BluetoothConnectionScreen> createState() => _BluetoothConnectionScreenState();
}

class _BluetoothConnectionScreenState extends State<BluetoothConnectionScreen> {

  final flutterReactiveBle = FlutterReactiveBle();

  late DiscoveredDevice _myDevice;

  late StreamSubscription<DiscoveredDevice> _scanStream;
  late QualifiedCharacteristic _rxCharacteristic;

  final Uuid serviceUuid = Uuid.parse("4fafc201-1fb5-459e-8fcc-c5c9c331914b");
  final Uuid characteristicUuid = Uuid.parse("beb5483e-36e1-4688-b7f5-ea07361b26a8");

  late List<int> _infoCharacteristics;

  bool _foundDeviceWaitingToConnect = false;
  bool _scanStarted = false;
  bool _connected = false;

  void _startScan() async {
    bool permGranted = false;
    setState(() {
      _scanStarted = true;
    });

    PermissionStatus permission;
    permission = await LocationPermissions().requestPermissions();
    if (permission == PermissionStatus.granted) permGranted = true;

    if (permGranted) {
      _scanStream = flutterReactiveBle
          .scanForDevices(withServices: [serviceUuid]).listen((device) {
        if (device.name.startsWith("L")) {
          setState(() {
            _myDevice = device;
            _foundDeviceWaitingToConnect = true;
          });
        }
      });
    }
  }

  void _connectToDevice() {

    _scanStream.cancel();

    Stream<ConnectionStateUpdate> _currentConnectionStream = flutterReactiveBle
        .connectToAdvertisingDevice(
        id: _myDevice.id,
        prescanDuration: const Duration(seconds: 5),
        withServices: [serviceUuid, characteristicUuid]);
    _currentConnectionStream.listen((event) {
      switch (event.connectionState) {
        case DeviceConnectionState.connected:
          {
            _rxCharacteristic = QualifiedCharacteristic(
                serviceId: serviceUuid,
                characteristicId: characteristicUuid,
                deviceId: event.deviceId);
            setState(() {
              _foundDeviceWaitingToConnect = false;
              _connected = true;
            });
            break;
          }

        case DeviceConnectionState.disconnected:
          {
            setState(() {
              _foundDeviceWaitingToConnect = true;
              _connected = false;
            });
            break;
          }
        default:
      }
    });
  }

  void _readFromDevice() async
  {
    if (_connected) {
    setState(() async {
      _infoCharacteristics.addAll(await flutterReactiveBle.readCharacteristic(_rxCharacteristic));
    });
    }
  }

  @override
  Widget build(BuildContext context) {

    _infoCharacteristics.addAll([1,2,3]);

    return Scaffold(
        appBar: AppBar(
        title: const Text("BLE"),
    ),
    body: SafeArea(child:
    Center(child: Column(
      mainAxisAlignment: MainAxisAlignment.spaceBetween,
      children: [
        Text("Started scan: $_scanStarted"),
      ElevatedButton.icon(
        icon: const Icon(
          Icons.bluetooth,
          color: Colors.yellow,
          size: 24.0,
        ),
        onPressed: () => _startScan(),
        label: const Text("Find and pair BLE device"),
        style: ElevatedButton.styleFrom(
          alignment: Alignment.centerLeft,
          fixedSize: const Size(
            290,
            32,
          ),
        ),
      ),
      Text("Device found? $_foundDeviceWaitingToConnect"),
      Text("Scan started? $_scanStarted"),
      Text("Connected? $_connected"),
      _connected ? Text("OK! Device name: ${_myDevice.id.toString()}") : Text("Device not connected!"),
      ElevatedButton.icon(
        icon: const Icon(
          Icons.bluetooth,
          color: Colors.yellow,
          size: 24.0,
        ),
        onPressed: () => _connectToDevice,
        label: const Text("Connect to BLE device"),
        style: ElevatedButton.styleFrom(
          alignment: Alignment.centerLeft,
          fixedSize: const Size(
            290,
            32,
          ),
        ),
      ),
        ElevatedButton.icon(
          icon: const Icon(
            Icons.bluetooth,
            color: Colors.yellow,
            size: 24.0,
          ),
          onPressed: () => _readFromDevice,
          label: const Text("Read information"),
          style: ElevatedButton.styleFrom(
            alignment: Alignment.centerLeft,
            fixedSize: const Size(
              290,
              32,
            ),
          ),
        ),
        _connected ? Text("OK ! $_infoCharacteristics") : Text("Device not connected!"),
    ],

    ))));
  }
}

我的Ffltter应用程序可以编译，但不能正常工作.它通过UUID找到设备，但无法连接到它.不知道为什么.最后，我想从我的设备中读取特征(用字符串表示的文本).欢迎任何建议！谢谢.

我添加了所有需要的应用程序权限(在Android Manifest文件中)，这个应用程序已经在Android OS 11中授予了所有需要的权限.当然，我已经在真实的设备上测试过它，手机.

我该怎么办？

日志(log)记录:

2023-04-28 22:15:17.784 10350-16111 flutter com.example.my_app I[38；5；12米之举─

10350-16111.我的应用程序I[38；5；12M│#0_BluToothConnectionScreenState._StartScan ScreenState._Start

10350-16111.我的应用程序I[38；5；12M│#1_BluToothConnectionScreenState.Build.(package:my_app/Screens/BluetoothConnection/BluetoothPairingScreen.dart:128:26)[0m

10350-16111Flutter 通信例如:my_app I[38；5；12m├┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄[0m

10350-28 22:15:17.785 10350-16111Flutter 通信.例如，my_app I[38；5；12M│?设备扫描已启动[0M

2023-04-28 22:15:17.785 10350-16111 flutter com.example.my_app I[38；5；12m回过头了─

2023-04-28 22:15:17.797 10350-16111 flutter com.example.my_app I[38；5；12米之举─

10350-16111.我的应用程序I[38；5；12M│#0_BluToothConnectionScreenState._StartScan ScreenState._Start

10350-16111Flutter 通信例如My_APP I[38；5；12M│#1[0M

10350-16111Flutter 通信例如:my_app I[38；5；12m├┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄[0m

10350-16111Flutter 通信例如:My_APP I[38；5；12 M│?许可已批准[0 M 10350-16111Flutter 通信例如:my_app I[38；5；12m└───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────[0m

2023-04-28 22:15:17.797 10350-16111 flutter com.example.my_app I[38；5；12米之举─

10350-16111.我的应用程序I[38；5；12M│#0_BluToothConnectionScreenState._StartScan ScreenState._Start

10350-16111Flutter 通信例如My_APP I[38；5；12M│#1[0M

10350-16111Flutter 通信例如:my_app I[38；5；12m├┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄[0m

10350-16111Flutter 通信例如:my_app I[38；5；12M│?Device Found:FALSE[0M

2023-04-28 22:15:17.797 10350-16111 flutter com.example.my_app I[38；5；12m回过头了─

10350-16177蓝牙适配器com.example.my_app D is LeEnabled():ON

10350-16177蓝牙适配器com.example.my_app D is LeEnabled():ON

10350-16191蓝牙 scanner .my_app D onScanerRegisted()-Status=0 scannerID=10 mScanerID=0

2023-04-28 22:15:17.815 2029-7327 AppOps PID-2029年UID 1002发出错误呼叫.包"com.example.my_app"不属于uid 1002.