flutter_bluetooth_serial 库自动调用cancelDiscovery()

Question

我正在开发一个 flutter 应用程序，用于列出我的手机并将其连接到应用程序内的其他设备。所以我使用的是 flutter_bluetooth_serial 包。我实现了与文档中几乎相同的代码，但在应用程序的初始化状态中调用 startDiscovery() 函数后，应用程序会无缘无故地立即调用 cancelDiscovery。代码成功运行了前两三次，但之后开始产生以下错误

D/BluetoothAdapter(15019): startDiscovery(): called by: com.example.bluetooth_app
D/FlutterBluePlugin(15019): Canceling discovery (stream closed)
D/BluetoothAdapter(15019): cancelDiscovery(): called by: com.example.bluetooth_app

不知道发生了什么。我正在使用 flutter 3.7 和软件包版本 0.4.0[最新]

这是完整应用程序的代码 -

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_bluetooth_serial/flutter_bluetooth_serial.dart';

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

  @override
  State<FooPage> createState() => _FooPageState();
}

class _FooPageState extends State<FooPage> {
  List<BluetoothDiscoveryResult> devices = [];

  late StreamSubscription<BluetoothDiscoveryResult>
      _discoveryStreamSubscription;

  @override
  void initState() {
    super.initState();
    _startDiscovery();
  }

  void _startDiscovery() {
    _discoveryStreamSubscription =
        FlutterBluetoothSerial.instance.startDiscovery().listen(
      (r) {
        print('device found');
        bool deviceFound = false;
        devices.forEach((element) {
          if (element.device.address == r.device.address) {
            deviceFound = true;
          }
        });
        if (!deviceFound) {
          setState(() {
            devices.add(r);
          });
        }
      },
    );

    _discoveryStreamSubscription.onDone(() {
      setState(() {
        print('stream closed');
        // _isDiscovering = false;
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    print(devices);
    return Scaffold(
      appBar: AppBar(
        title: Text("Bluetooth Devices"),
      ),
      body: devices.length == 0
          ? Center(
              child: Text('No Nearby devices can be found currently...'),
            )
          : ListView(
              children: devices
                  .map(
                    (e) => ListTile(
                      title: Text(e.device.name!),
                      subtitle: Text(e.device.type.stringValue),
                    ),
                  )
                  .toList(),
            ),
    );
  }
}

Answer 1

在开始之前

FlutterBluetoothSerial.instance.startDiscovery()

， 您需要先使用

FlutterBluetoothSerial.instance.cancelDiscovery()

取消它。 这解决了我的问题