Flutter蓝牙通信插件flutter_ble_central的使用

发布于 1周前 作者 nodeper 来自 Flutter

Flutter蓝牙通信插件flutter_ble_central的使用

flutter_ble_central

一个用于在中心模式下扫描蓝牙低功耗（BLE）数据的Flutter插件。

开始使用

这个项目是一个Flutter插件包的起点，它包含针对Android和/或iOS平台的特定平台实现代码。

要开始使用Flutter，请查看我们的在线文档，其中包含教程、示例、移动开发指南以及完整的API引用。

示例代码

以下是使用flutter_ble_central插件的基本示例：

import 'dart:async';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  [@override](/user/override)
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Map<String, ScanResult> devices = {};
  bool isScanning = false;
  int packetsFound = 0;
  int? queue = 0;

  [@override](/user/override)
  void initState() {
    super.initState();

    Timer.periodic(const Duration(seconds: 1), (timer) {
      setState(() {
        debugPrint('Packets found: $packetsFound, in queue $queue');
      });
    });

    FlutterBleCentral().onScanError?.listen((event) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            '错误: ${AndroidError.values[event]}, code: $event',
          ),
        ),
      );
      debugPrint('Error: ${AndroidError.values[event]}, code: $event');
    });

    FlutterBleCentral().onScanResult.listen((event) {
      packetsFound++;
    });
  }

  Future<void> _requestPermissions() async {
    final hasPermission = await FlutterBleCentral().hasPermission();
    switch (hasPermission) {
      case BluetoothCentralState.denied:
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            backgroundColor: Colors.red,
            content: Text(
              "我们没有权限，现在请求!",
            ),
          ),
        );

        await _requestPermissions();
        break;
      default:
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            backgroundColor: Colors.green,
            content: Text(
              '状态: $hasPermission!',
            ),
          ),
        );
        break;
    }
  }

  final _messangerKey = GlobalKey<ScaffoldMessengerState>();

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      scaffoldMessengerKey: _messangerKey,
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Flutter BLE Central 示例'),
          actions: <Widget>[
            IconButton(
              onPressed: () => setState(() {
                FlutterBleCentral().stop();
              }),
              icon: const Icon(Icons.lock_reset),
            ),
            IconButton(
              onPressed: _requestPermissions,
              icon: const Icon(Icons.security),
            ),
            if (isScanning)
              IconButton(
                icon: const Icon(Icons.pause_circle_filled),
                onPressed: () => setState(() {
                  isScanning = false;
                  FlutterBleCentral().stop();
                }),
              )
            else
              IconButton(
                icon: const Icon(Icons.play_arrow),
                onPressed: () async {
                  final messenger = _messangerKey.currentState!;
                  final state = await FlutterBleCentral().start();
                  switch (state) {
                    case BluetoothCentralState.ready:
                    case BluetoothCentralState.granted:
                      setState(() {
                        isScanning = true;
                        devices.clear();
                      });
                      break;
                    case BluetoothCentralState.denied:
                      messenger.showSnackBar(
                        const SnackBar(
                          content: Text(
                            '蓝牙被拒绝，我们可以再次请求!',
                          ),
                        ),
                      );
                      break;
                    case BluetoothCentralState.permanentlyDenied:
                      messenger.showSnackBar(
                        const SnackBar(
                          content: Text(
                            '蓝牙被永久拒绝，我们不能再请求!',
                          ),
                        ),
                      );
                      break;
                    case BluetoothCentralState.restricted:
                      // TODO: 处理这种情况。
                      break;
                    case BluetoothCentralState.limited:
                      // TODO: 处理这种情况。
                      break;
                    case BluetoothCentralState.turnedOff:
                      messenger.showSnackBar(
                        const SnackBar(
                          content: Text(
                            '蓝牙已关闭。',
                          ),
                        ),
                      );
                      break;
                    case BluetoothCentralState.unsupported:
                      messenger.showSnackBar(
                        const SnackBar(
                          content: Text(
                            '设备不支持蓝牙。',
                          ),
                        ),
                      );
                      break;
                    case BluetoothCentralState.unknown:
                      messenger.showSnackBar(
                        const SnackBar(
                          content: Text(
                            '未知错误..',
                          ),
                        ),
                      );
                      break;
                  }
                },
              ),
          ],
        ),
        body: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            ElevatedButton(
              onPressed: () async {
                if (isScanning) {
                  FlutterBleCentral().stop();
                  isScanning = false;
                } else {
                  isScanning = true;
                  devices.clear();
                  FlutterBleCentral().start(
                    scanSettings: ScanSettings(
                      scanMode: ScanMode.scanModeLowLatency,
                    ),
                  );
                  await Future.delayed(
                    const Duration(
                      seconds: 30,
                    ),
                  );
                  FlutterBleCentral().stop();
                  isScanning = false;
                }
              },
              child: const Text('30秒测试'),
            ),
            ElevatedButton(
              onPressed: () => FlutterBleCentral().openBluetoothSettings(),
              child: const Text('蓝牙设置'),
            ),
            ElevatedButton(
              onPressed: () => FlutterBleCentral().openAppSettings(),
              child: const Text('应用设置'),
            ),
            Text('找到的数据包: $packetsFound, 队列中: $queue'),
            ListView.separated(
              shrinkWrap: true,
              padding: const EdgeInsets.all(8),
              itemBuilder: (BuildContext context, int index) {
                final scanResult = devices.values.elementAt(index);
                return Card(
                  child: Padding(
                    padding: const EdgeInsets.all(8.0),
                    child: Row(
                      children: <Widget>[
                        const Icon(Icons.bluetooth),
                        Expanded(
                          child: Column(
                            crossAxisAlignment: CrossAxisAlignment.start,
                            children: <Widget>[
                              Text('${scanResult.scanRecord?.deviceName}'),
                              Text('${scanResult.device?.address}'),
                              Text('RSSI: ${scanResult.rssi}'),
                            ],
                          ),
                        ),
                      ],
                    ),
                  ),
                );
              },
              separatorBuilder: (context, index) => const SizedBox(height: 5),
              itemCount: devices.length,
            ),
          ],
        ),
      ),
    );
  }
}

代码解释

  1. 导入必要的库

    import 'dart:async';

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

  2. 初始化应用

    void main() {
  runApp(const MyApp());
}

  3. 定义主应用状态

    class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  [@override](/user/override)
  State<MyApp> createState() => _MyAppState();
}

  4. 处理蓝牙扫描结果

    class _MyAppState extends State<MyApp> {
  Map<String, ScanResult> devices = {};
  bool isScanning = false;
  int packetsFound = 0;
  int? queue = 0;

  [@override](/user/override)
  void initState() {
    super.initState();

    Timer.periodic(const Duration(seconds: 1), (timer) {
      setState(() {
        debugPrint('Packets found: $packetsFound, in queue $queue');
      });
    });

    FlutterBleCentral().onScanError?.listen((event) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(
            '错误: ${AndroidError.values[event]}, code: $event',
          ),
        ),
      );
      debugPrint('Error: ${AndroidError.values[event]}, code: $event');
    });

    FlutterBleCentral().onScanResult.listen((event) {
      packetsFound++;
    });
  }

  5. 请求权限

    Future<void> _requestPermissions() async {
  final hasPermission = await FlutterBleCentral().hasPermission();
  switch (hasPermission) {
    case BluetoothCentralState.denied:
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          backgroundColor: Colors.red,
          content: Text(
            "我们没有权限，现在请求!",
          ),
        ),
      );

      await _requestPermissions();
      break;
    default:
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          backgroundColor: Colors.green,
          content: Text(
            '状态: $hasPermission!',
          ),
        ),
      );
      break;
  }
}

  6. 构建UI

    final _messangerKey = GlobalKey<ScaffoldMessengerState>();

[@override](/user/override)
Widget build(BuildContext context) {
  return MaterialApp(
    scaffoldMessengerKey: _messangerKey,
    home: Scaffold(
      appBar: AppBar(
        title: const Text('Flutter BLE Central 示例'),
        actions: <Widget>[
          IconButton(
            onPressed: () => setState(() {
              FlutterBleCentral().stop();
            }),
            icon: const Icon(Icons.lock_reset),
          ),
          IconButton(
            onPressed: _requestPermissions,
            icon: const Icon(Icons.security),
          ),
          if (isScanning)
            IconButton(
              icon: const Icon(Icons.pause_circle_filled),
              onPressed: () => setState(() {
                isScanning = false;
                FlutterBleCentral().stop();
              }),
            )
          else
            IconButton(
              icon: const Icon(Icons.play_arrow),
              onPressed: () async {
                final messenger = _messangerKey.currentState!;
                final state = await FlutterBleCentral().start();
                switch (state) {
                  case BluetoothCentralState.ready:
                  case BluetoothCentralState.granted:
                    setState(() {
                      isScanning = true;
                      devices.clear();
                    });
                    break;
                  case BluetoothCentralState.denied:
                    messenger.showSnackBar(
                      const SnackBar(
                        content: Text(
                          '蓝牙被拒绝，我们可以再次请求!',
                        ),
                      ),
                    );
                    break;
                  case BluetoothCentralState.permanentlyDenied:
                    messenger.showSnackBar(
                      const SnackBar(
                        content: Text(
                          '蓝牙被永久拒绝，我们不能再请求!',
                        ),
                      ),
                    );
                    break;
                  case BluetoothCentralState.restricted:
                    // TODO: 处理这种情况。
                    break;
                  case BluetoothCentralState.limited:
                    // TODO: 处理这种情况。
                    break;
                  case BluetoothCentralState.turnedOff:
                    messenger.showSnackBar(
                      const SnackBar(
                        content: Text(
                          '蓝牙已关闭。',
                        ),
                      ),
                    );
                    break;
                  case BluetoothCentralState.unsupported:
                    messenger.showSnackBar(
                      const SnackBar(
                        content: Text(
                          '设备不支持蓝牙。',
                        ),
                      ),
                    );
                    break;
                  case BluetoothCentralState.unknown:
                    messenger.showSnackBar(
                      const SnackBar(
                        content: Text(
                          '未知错误..',
                        ),
                      ),
                    );
                    break;
                }
              },
            ),
        ],
      ),
      body: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          ElevatedButton(
            onPressed: () async {
              if (isScanning) {
                FlutterBleCentral().stop();
                isScanning = false;
              } else {
                isScanning = true;
                devices.clear();
                FlutterBleCentral().start(
                  scanSettings: ScanSettings(
                    scanMode: ScanMode.scanModeLowLatency,
                  ),
                );
                await Future.delayed(
                  const Duration(
                    seconds: 30,
                  ),
                );
                FlutterBleCentral().stop();
                isScanning = false;
              }
            },
            child: const Text('30秒测试'),
          ),
          ElevatedButton(
            onPressed: () => FlutterBleCentral().openBluetoothSettings(),
            child: const Text('蓝牙设置'),
          ),
          ElevatedButton(
            onPressed: () => FlutterBleCentral().openAppSettings(),
            child: const Text('应用设置'),
          ),
          Text('找到的数据包: $packetsFound, 队列中: $queue'),
          ListView.separated(
            shrinkWrap: true,
            padding: const EdgeInsets.all(8),
            itemBuilder: (BuildContext context, int index) {
              final scanResult = devices.values.elementAt(index);
              return Card(
                child: Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: Row(
                    children: <Widget>[
                      const Icon(Icons.bluetooth),
                      Expanded(
                        child: Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: <Widget>[
                            Text('${scanResult.scanRecord?.deviceName}'),
                            Text('${scanResult.device?.address}'),
                            Text('RSSI: ${scanResult.rssi}'),
                          ],
                        ),
                      ),
                    ],
                  ),
                ),
              );
            },
            separatorBuilder: (context, index) => const SizedBox(height: 5),
            itemCount: devices.length,
          ),
        ],
      ),
    ),
  );
}

更多关于Flutter蓝牙通信插件flutter_ble_central的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html

1 回复

更多关于Flutter蓝牙通信插件flutter_ble_central的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html


当然，以下是一个关于如何使用 flutter_ble_central 插件进行蓝牙通信的示例代码。这个示例展示了如何扫描设备、连接到设备以及读写蓝牙特征值。

首先，确保你已经在 pubspec.yaml 文件中添加了 flutter_ble_central 依赖：

dependencies:
  flutter:
    sdk: flutter
  flutter_ble_central: ^2.0.0 # 请根据需要检查最新版本

然后，运行 flutter pub get 来获取依赖。

接下来是主要的 Dart 代码示例：

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  FlutterBleCentral _flutterBleCentral = FlutterBleCentral();
  List<DiscoveredDevice> _devices = [];
  ConnectedDevice? _connectedDevice;
  Characteristic? _characteristic;

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

  Future<void> initBle() async {
    // 初始化 Bluetooth 适配器
    bool isBluetoothAvailable = await _flutterBleCentral.isBluetoothAvailable();
    if (!isBluetoothAvailable) {
      // 处理蓝牙不可用的情况
      return;
    }

    bool isBluetoothEnabled = await _flutterBleCentral.isBluetoothEnabled();
    if (!isBluetoothEnabled) {
      // 请求用户开启蓝牙
      bool result = await _flutterBleCentral.requestBluetoothEnable();
      if (!result) {
        // 用户拒绝开启蓝牙
        return;
      }
    }

    // 开始扫描设备
    _flutterBleCentral.scanForDevices(timeout: Duration(seconds: 5)).listen(
      (List<DiscoveredDevice> result) {
        setState(() {
          _devices = result;
        });
      },
      onError: (dynamic error) {
        print('Scan error: $error');
      },
      onDone: () {
        print('Scan done.');
      },
    );
  }

  Future<void> connectToDevice(DiscoveredDevice device) async {
    _connectedDevice = await _flutterBleCentral.connectToDevice(device.id);
    if (_connectedDevice != null) {
      // 获取服务
      List<BluetoothService> services = await _connectedDevice!.discoverServices();
      services.forEach((service) {
        // 获取特征值
        service.characteristics.forEach((characteristic) {
          setState(() {
            _characteristic = characteristic;
          });
          // 可以在这里根据 UUID 筛选需要的特征值
        });
      });
    }
  }

  Future<void> readCharacteristic() async {
    if (_characteristic != null && _connectedDevice != null) {
      List<int> value = await _connectedDevice!.readCharacteristic(_characteristic!.uuid);
      print('Characteristic value: ${bytesToHex(value)}');
    }
  }

  Future<void> writeCharacteristic(List<int> value) async {
    if (_characteristic != null && _connectedDevice != null) {
      await _connectedDevice!.writeCharacteristic(_characteristic!.uuid, value);
      print('Characteristic written.');
    }
  }

  String bytesToHex(List<int> bytes) {
    return bytes.map((byte) => byte.toRadixString(16).padLeft(2, '0')).join();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter BLE Example'),
        ),
        body: Column(
          children: [
            Expanded(
              child: ListView.builder(
                itemCount: _devices.length,
                itemBuilder: (context, index) {
                  return ListTile(
                    title: Text(_devices[index].name ?? 'Unknown Device'),
                    subtitle: Text(_devices[index].id),
                    onTap: () {
                      connectToDevice(_devices[index]);
                    },
                  );
                },
              ),
            ),
            ElevatedButton(
              onPressed: _connectedDevice != null ? () => readCharacteristic() : null,
              child: Text('Read Characteristic'),
            ),
            ElevatedButton(
              onPressed: _connectedDevice != null ? () => writeCharacteristic([0x01, 0x02, 0x03]) : null,
              child: Text('Write Characteristic'),
            ),
          ],
        ),
      ),
    );
  }
}

解释

  1. 依赖初始化：在 pubspec.yaml 中添加 flutter_ble_central 依赖，并运行 flutter pub get。

  2. Bluetooth 初始化：在 initBle 方法中检查蓝牙是否可用和已启用，并在必要时请求用户开启蓝牙。

  3. 扫描设备：使用 _flutterBleCentral.scanForDevices 方法开始扫描设备，并将扫描到的设备存储在 _devices 列表中。

  4. 连接设备：在 connectToDevice 方法中，根据设备 ID 连接到设备，并发现服务及其特征值。

  5. 读写特征值：在 readCharacteristic 和 writeCharacteristic 方法中，分别读取和写入特征值。

  6. UI：在 build 方法中构建一个简单的 UI，显示扫描到的设备列表，并提供按钮来读取和写入特征值。

这个示例展示了基本的蓝牙通信流程，你可以根据具体需求进一步扩展和修改代码。

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