Flutter蓝牙通信插件flutter_blue_plus的使用

简介

FlutterBluePlus 是一个用于Flutter的Bluetooth Low Energy (BLE) 插件，它支持大多数平台上的BLE Central角色功能。本文档将详细介绍如何在Flutter项目中使用flutter_blue_plus进行蓝牙通信，并提供完整的示例代码。

简介

FlutterBluePlus 是一个用于Flutter的Bluetooth Low Energy (BLE) 插件，它支持大多数平台上的BLE Central角色功能。如果你需要BLE Peripheral角色功能，可以考虑使用其他插件如FlutterBlePeripheral或bluetooth_low_energy。

准备工作

Android配置

更改minSdkVersion：在android/app/build.gradle文件中设置minSdkVersion为21。
```
android {
  defaultConfig {
    minSdkVersion 21
  }
}
```

添加权限：在android/app/src/main/AndroidManifest.xml文件中添加必要的权限。

<uses-feature android:name="android.hardware.bluetooth_le" android:required="false" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN" android:usesPermissionFlags="neverForLocation" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH" android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" android:maxSdkVersion="30"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" android:maxSdkVersion="28" />

Proguard规则：在project/android/app/proguard-rules.pro文件中添加以下内容以避免发布模式下的错误。
```
-keep class com.lib.flutter_blue_plus.* { *; }
```

iOS配置

在ios/Runner/Info.plist文件中添加以下内容。

<key>NSBluetoothAlwaysUsageDescription</key>
<string>This app needs Bluetooth to function</string>

基本用法

错误处理

FlutterBluePlus对错误处理非常严格，所有来自原生平台的错误都会被检查并抛出异常。

// Streams returned by FlutterBluePlus never emit any errors and never close.
var subscription = FlutterBluePlus.onScanResults.listen((results) {
    if (results.isNotEmpty) {
        ScanResult r = results.last;
        print('${r.device.remoteId}: "${r.advertisementData.advName}" found!');
    }
}, onError: (e) => print(e));

设置日志级别

FlutterBluePlus.setLogLevel(LogLevel.verbose, color: true);

蓝牙开关状态

if (await FlutterBluePlus.isSupported == false) {
    print("Bluetooth not supported by this device");
    return;
}

var subscription = FlutterBluePlus.adapterState.listen((state) {
    print(state);
    if (state == BluetoothAdapterState.on) {
        // Start scanning, connecting, etc.
    } else {
        // Show an error to the user, etc.
    }
});

if (Platform.isAndroid) {
    await FlutterBluePlus.turnOn();
}
subscription.cancel();

扫描设备

var subscription = FlutterBluePlus.onScanResults.listen((results) {
    if (results.isNotEmpty) {
        ScanResult r = results.last;
        print('${r.device.remoteId}: "${r.advertisementData.advName}" found!');
    }
}, onError: (e) => print(e));

await FlutterBluePlus.startScan(
  withServices:[Guid("180D")],
  withNames:["Bluno"],
  timeout: Duration(seconds:15));

await FlutterBluePlus.isScanning.where((val) => val == false).first;

连接设备

var subscription = device.connectionState.listen((state) async {
    if (state == BluetoothConnectionState.disconnected) {
        print("${device.disconnectReason?.code} ${device.disconnectReason?.description}");
    }
});

await device.connect();

await device.disconnect();
subscription.cancel();

自动连接

await device.connect(autoConnect: true, mtu: null);

await device.connectionState.where((val) => val == BluetoothConnectionState.connected).first;

await device.disconnect();

保存设备

final String remoteId = await File('/remoteId.txt').readAsString();
var device = BluetoothDevice.fromId(remoteId);
await device.connect(autoConnect: true);

MTU

final subscription = device.mtu.listen((int mtu) {
    print("mtu $mtu");
});

if (Platform.isAndroid) {
    await device.requestMtu(512);
}

发现服务

List<BluetoothService> services = await device.discoverServices();
services.forEach((service) {
    // Do something with service
});

读取特性

var characteristics = service.characteristics;
for(BluetoothCharacteristic c in characteristics) {
    if (c.properties.read) {
        List<int> value = await c.read();
        print(value);
    }
}

写入特性

await c.write([0x12, 0x34]);

订阅特性

final subscription = characteristic.onValueReceived.listen((value) {
    // Handle value received
});

await characteristic.setNotifyValue(true);

读取和写入描述符

var descriptors = characteristic.descriptors;
for(BluetoothDescriptor d in descriptors) {
    List<int> value = await d.read();
    print(value);
}

await d.write([0x12, 0x34]);

获取已连接设备

List<BluetoothDevice> devs = FlutterBluePlus.connectedDevices;
for (var d in devs) {
    print(d);
}

获取系统设备

List<Guid> withServices = [Guid("180F")];
List<BluetoothDevice> devs = await FlutterBluePlus.systemDevices(withServices);
for (var d in devs) {
    await d.connect();
    await d.discoverServices();
}

创建绑定（仅限Android）

final bsSubscription = device.bondState.listen((value) {
    print("$value prev:{$device.prevBondState}");
});

await device.createBond();

await device.removeBond();

事件API

FlutterBluePlus.events.onConnectionStateChanged.listen((event)) {
    print('${event.device} ${event.connectionState}');
}

示例代码

以下是flutter_blue_plus的完整示例代码：

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';

void main() {
  FlutterBluePlus.setLogLevel(LogLevel.verbose, color: true);
  runApp(const FlutterBlueApp());
}

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

  @override
  State<FlutterBlueApp> createState() => _FlutterBlueAppState();
}

class _FlutterBlueAppState extends State<FlutterBlueApp> {
  BluetoothAdapterState _adapterState = BluetoothAdapterState.unknown;
  late StreamSubscription<BluetoothAdapterState> _adapterStateStateSubscription;

  @override
  void initState() {
    super.initState();
    _adapterStateStateSubscription = FlutterBluePlus.adapterState.listen((state) {
      _adapterState = state;
      if (mounted) {
        setState(() {});
      }
    });
  }

  @override
  void dispose() {
    _adapterStateStateSubscription.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    Widget screen = _adapterState == BluetoothAdapterState.on
        ? const ScanScreen()
        : BluetoothOffScreen(adapterState: _adapterState);

    return MaterialApp(
      color: Colors.lightBlue,
      home: screen,
      navigatorObservers: [BluetoothAdapterStateObserver()],
    );
  }
}

class BluetoothAdapterStateObserver extends NavigatorObserver {
  StreamSubscription<BluetoothAdapterState>? _adapterStateSubscription;

  @override
  void didPush(Route route, Route? previousRoute) {
    super.didPush(route, previousRoute);
    if (route.settings.name == '/DeviceScreen') {
      _adapterStateSubscription ??= FlutterBluePlus.adapterState.listen((state) {
        if (state != BluetoothAdapterState.on) {
          navigator?.pop();
        }
      });
    }
  }

  @override
  void didPop(Route route, Route? previousRoute) {
    super.didPop(route, previousRoute);
    _adapterStateSubscription?.cancel();
    _adapterStateSubscription = null;
  }
}

通过上述代码和说明，你应该能够顺利地在Flutter项目中使用flutter_blue_plus进行蓝牙通信。如果有任何问题或需要进一步的帮助，请参考官方文档或社区资源。

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

wuwangju 1楼•2 天前

更多关于Flutter蓝牙通信插件flutter_blue_plus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_blue_plus 插件进行蓝牙通信的示例代码。这个插件是对 flutter_blue 的增强，提供了更多的功能和更好的性能。请确保你已经在 pubspec.yaml 文件中添加了 flutter_blue_plus 依赖，并且已经运行了 flutter pub get。

1. 添加依赖

首先，在你的 pubspec.yaml 文件中添加以下依赖：

dependencies:
  flutter:
    sdk: flutter
  flutter_blue_plus: ^x.y.z  # 请替换为最新版本号

2. 导入插件并初始化

在你的 Dart 文件中导入 flutter_blue_plus 插件：

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

3. 扫描和连接设备

以下是一个简单的示例，展示如何扫描蓝牙设备并连接到其中一个设备：

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: BluetoothScreen(),
    );
  }
}

class BluetoothScreen extends StatefulWidget {
  @override
  _BluetoothScreenState createState() => _BluetoothScreenState();
}

class _BluetoothScreenState extends State<BluetoothScreen> {
  FlutterBluePlus flutterBluePlus = FlutterBluePlus.instance;
  List<BluetoothDevice> devices = [];
  BluetoothDevice? selectedDevice;

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

  Future<void> scanForDevices() async {
    bool isScanning = true;
    flutterBluePlus.startScan(allowDuplicates: false).listen((scanResult) {
      setState(() {
        devices.add(scanResult.device);
      });
    }).onDone(() {
      if (isScanning) setState(() {}); // trigger a UI update when scanning is stopped
    });

    // Stop scanning after 10 seconds
    Future.delayed(Duration(seconds: 10), () {
      isScanning = false;
      flutterBluePlus.stopScan();
    });
  }

  Future<void> connectToDevice(BluetoothDevice device) async {
    setState(() {
      selectedDevice = device;
    });

    try {
      await device.connect();
      print('Connected to ${device.name}');
      // Here you can discover services, characteristics, etc.
    } catch (e) {
      print('Failed to connect: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Bluetooth Example'),
      ),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Expanded(
            child: ListView.builder(
              itemCount: devices.length,
              itemBuilder: (context, index) {
                final device = devices[index];
                return ListTile(
                  title: Text(device.name ?? 'Unknown device'),
                  subtitle: Text(device.id.toString()),
                  trailing: Icon(Icons.arrow_forward),
                  onTap: () => connectToDevice(device),
                );
              },
            ),
          ),
          if (selectedDevice != null)
            Text('Connected to: ${selectedDevice?.name ?? 'No Device'}'),
        ],
      ),
    );
  }
}

4. 发现和交互服务与特征值

一旦连接到设备，你可以发现和交互服务与特征值。以下是一个简单的示例，展示如何读取和写入特征值：

Future<void> interactWithServices(BluetoothDevice device) async {
  // Discover services
  List<BluetoothService> services = await device.discoverServices();

  // Find a specific service (you need to know the UUID of the service you want)
  BluetoothService? service = services.firstWhere(
    (s) => s.uuid.toString().contains('your-service-uuid'),
    orElse: () => null,
  );

  if (service == null) {
    print('Service not found');
    return;
  }

  // Discover characteristics of the service
  List<BluetoothCharacteristic> characteristics = await service.characteristics();

  // Find a specific characteristic (you need to know the UUID of the characteristic)
  BluetoothCharacteristic? characteristic = characteristics.firstWhere(
    (c) => c.uuid.toString().contains('your-characteristic-uuid'),
    orElse: () => null,
  );

  if (characteristic == null) {
    print('Characteristic not found');
    return;
  }

  // Read value from characteristic
  List<int> value = await characteristic.read();
  print('Value read: ${bytesToHex(value)}');

  // Write value to characteristic
  List<int> newValue = hexToBytes('new-value-in-hex');
  await characteristic.write(newValue);
  print('Value written');
}

// Helper function to convert bytes to hex string
String bytesToHex(List<int> bytes) {
  return bytes.map((byte) => byte.toRadixString(16).padLeft(2, '0')).join();
}

// Helper function to convert hex string to bytes
List<int> hexToBytes(String hexString) {
  return hexString.replaceAll(" ", "")
      .split("")
      .map((hex) => int.parse(hex + hex, radix: 16))
      .toList();
}

5. 使用交互函数

你可以在 connectToDevice 函数中调用 interactWithServices 函数：

Future<void> connectToDevice(BluetoothDevice device) async {
  setState(() {
    selectedDevice = device;
  });

  try {
    await device.connect();
    print('Connected to ${device.name}');
    await interactWithServices(device);
  } catch (e) {
    print('Failed to connect: $e');
  }
}

这个示例代码展示了如何使用 flutter_blue_plus 插件扫描蓝牙设备、连接到设备，并与设备上的服务和特征值进行交互。请注意，你需要替换 'your-service-uuid' 和 'your-characteristic-uuid' 为实际设备的 UUID。

Flutter蓝牙通信插件flutter_blue_plus的使用

Flutter蓝牙通信插件flutter_blue_plus的使用

简介

目录

简介

准备工作

Android配置

iOS配置

基本用法

错误处理

设置日志级别

蓝牙开关状态

扫描设备

连接设备

自动连接

保存设备

MTU

发现服务

读取特性

写入特性

订阅特性

读取和写入描述符

获取已连接设备

获取系统设备

创建绑定（仅限Android）

事件API

示例代码

1. 添加依赖

2. 导入插件并初始化

3. 扫描和连接设备

4. 发现和交互服务与特征值

5. 使用交互函数