Flutter低功耗蓝牙通信插件bluetooth_low_energy的使用

简介

bluetooth_low_energy 是一个Flutter插件，用于控制低功耗蓝牙（BLE），支持中央设备（Central）和外围设备（Peripheral）角色。以下是该插件的主要功能和使用方法。

CentralManager API 支持情况

PeripheralManager API 支持情况

开始使用

添加依赖

在 pubspec.yaml 文件中添加 bluetooth_low_energy 依赖：

dependencies:
  bluetooth_low_energy: ^<latest-version>

注意： 低功耗蓝牙不适用于模拟器，请使用具有蓝牙功能的物理设备进行开发。

平台特定配置

Android

确保你的 android/app/build.gradle 文件中的 minSdk 设置为21或更高。

iOS 和 macOS

根据苹果文档，你必须在iOS 13及以上版本包含 NSBluetoothAlwaysUsageDescription，在iOS 13之前包含 NSBluetoothPeripheralUsageDescription。

对于macOS，开发者需要配置应用沙盒以访问受限资源。

Windows

PeripheralManager#startAdvertising 不支持 name 参数。

Linux

PeripheralManager API 尚未实现，因为 bluez 不支持此功能。

示例代码

以下是一个完整的示例应用程序，展示了如何使用 bluetooth_low_energy 插件：

import 'dart:async';
import 'dart:developer';

import 'package:flutter/material.dart';
import 'package:logging/logging.dart';
import 'package:bluetooth_low_energy/bluetooth_low_energy.dart';

void main() {
  runZonedGuarded(onStartUp, onCrashed);
}

void onStartUp() async {
  Logger.root.onRecord.listen(onLogRecord);
  hierarchicalLoggingEnabled = true;

  // 初始化蓝牙管理器
  final centralManager = CentralManager();
  await centralManager.startDiscovery();

  runApp(const MyApp());
}

void onCrashed(Object error, StackTrace stackTrace) {
  Logger.root.shout('App crashed.', error, stackTrace);
}

void onLogRecord(LogRecord record) {
  log(
    record.message,
    time: record.time,
    sequenceNumber: record.sequenceNumber,
    level: record.level.value,
    name: record.loggerName,
    zone: record.zone,
    error: record.error,
    stackTrace: record.stackTrace,
  );
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'BLE Example',
      theme: ThemeData.light().copyWith(
        materialTapTargetSize: MaterialTapTargetSize.padded,
      ),
      darkTheme: ThemeData.dark().copyWith(
        materialTapTargetSize: MaterialTapTargetSize.padded,
      ),
      home: const BLEHomePage(),
    );
  }
}

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

  @override
  State<BLEHomePage> createState() => _BLEHomePageState();
}

class _BLEHomePageState extends State<BLEHomePage> {
  final CentralManager _centralManager = CentralManager();
  List<DiscoveredPeripheral> _peripherals = [];

  @override
  void initState() {
    super.initState();
    _centralManager.discovered.listen((event) {
      setState(() {
        _peripherals.add(event);
      });
    });
    _centralManager.startDiscovery();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('BLE Devices'),
      ),
      body: ListView.builder(
        itemCount: _peripherals.length,
        itemBuilder: (context, index) {
          final peripheral = _peripherals[index];
          return ListTile(
            title: Text(peripheral.name ?? 'Unknown Device'),
            subtitle: Text(peripheral.identifier),
            onTap: () {
              Navigator.push(
                context,
                MaterialPageRoute(
                  builder: (context) => DeviceDetailPage(peripheral: peripheral),
                ),
              );
            },
          );
        },
      ),
    );
  }
}

class DeviceDetailPage extends StatefulWidget {
  final DiscoveredPeripheral peripheral;

  const DeviceDetailPage({super.key, required this.peripheral});

  @override
  State<DeviceDetailPage> createState() => _DeviceDetailPageState();
}

class _DeviceDetailPageState extends State<DeviceDetailPage> {
  late StreamSubscription<ConnectionState> _connectionStateSubscription;
  bool _isConnected = false;

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

  Future<void> _connectToDevice() async {
    try {
      await widget.peripheral.connect();
      _connectionStateSubscription = widget.peripheral.connectionStateChanged.listen((state) {
        if (mounted) {
          setState(() {
            _isConnected = state == ConnectionState.connected;
          });
        }
      });
    } catch (e) {
      log('Failed to connect: $e');
    }
  }

  @override
  void dispose() {
    _connectionStateSubscription.cancel();
    widget.peripheral.disconnect();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.peripheral.name ?? 'Unknown Device'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(_isConnected ? 'Connected' : 'Disconnected'),
            ElevatedButton(
              onPressed: _isConnected ? null : () async {
                await widget.peripheral.connect();
                setState(() {
                  _isConnected = true;
                });
              },
              child: const Text('Connect'),
            ),
            ElevatedButton(
              onPressed: _isConnected ? () async {
                await widget.peripheral.disconnect();
                setState(() {
                  _isConnected = false;
                });
              } : null,
              child: const Text('Disconnect'),
            ),
          ],
        ),
      ),
    );
  }
}

这个示例展示了如何初始化蓝牙管理器、发现设备并连接到设备。你可以根据需要扩展此代码以实现更多功能，如读取和写入特征值等。