Flutter蓝牙通信插件flutter_blue_plugin的使用

简介

flutter_blue_plugin 是一个用于Flutter的蓝牙插件，支持iOS和Android平台。它允许开发者扫描、连接到附近的蓝牙设备，并与这些设备进行交互。

Alpha版本注意

此库在生产应用中积极开发，API可能会随着版本更新而变化，请确保准备好应对可能的不兼容更改。此外，该插件必须在真实设备上测试。

跨平台蓝牙LE

通过FlutterBlue实例，您可以扫描并连接附近的设备（BluetoothDevice）。一旦连接到设备，可以通过发现服务（BluetoothService）、特性（BluetoothCharacteristic）和描述符（BluetoothDescriptor）来直接与之交互。

使用指南

获取实例

FlutterBlue flutterBlue = FlutterBlue.instance;

扫描设备

// 开始扫描
flutterBlue.startScan(timeout: Duration(seconds: 4));

// 监听扫描结果
var subscription = flutterBlue.scanResults.listen((results) {
    // 处理扫描结果
    for (ScanResult r in results) {
        print('${r.device.name} found! rssi: ${r.rssi}');
    }
});

// 停止扫描
flutterBlue.stopScan();

连接到设备

// 连接到设备
await device.connect();

// 断开连接
device.disconnect();

发现服务

List<BluetoothService> services = await device.discoverServices();
services.forEach((service) {
    // 处理服务
});

读写特性

// 读取所有特性
var characteristics = service.characteristics;
for(BluetoothCharacteristic c in characteristics) {
    List<int> value = await c.read();
    print(value);
}

// 写入特性
await c.write([0x12, 0x34]);

设置通知并监听变化

await characteristic.setNotifyValue(true);
characteristic.value.listen((value) {
    // 处理新值
});

示例代码

下面是一个完整的示例demo，展示了如何使用flutter_blue_plugin进行蓝牙设备的扫描、连接和服务发现：

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Blue Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: FindDevicesScreen(),
    );
  }
}

class FindDevicesScreen extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Find Devices'),
      ),
      body: RefreshIndicator(
        onRefresh: () => _startScan(),
        child: SingleChildScrollView(
          child: Column(
            children: <Widget>[
              StreamBuilder<List<BluetoothDevice>>(
                stream: Stream.periodic(Duration(seconds: 2))
                    .asyncMap((_) => FlutterBlue.instance.connectedDevices),
                initialData: [],
                builder: (c, snapshot) => Column(
                  children: snapshot.data!
                      .map((d) => ListTile(
                            title: Text(d.name),
                            subtitle: Text(d.id.toString()),
                          ))
                      .toList(),
                ),
              ),
              StreamBuilder<List<ScanResult>>(
                stream: FlutterBlue.instance.scanResults,
                initialData: [],
                builder: (c, snapshot) => Column(
                  children: snapshot.data!
                      .map(
                        (r) => ScanResultTile(
                          result: r,
                          onTap: () => Navigator.of(context)
                              .push(MaterialPageRoute(builder: (context) {
                            r.device.connect();
                            return DeviceScreen(device: r.device);
                          })),
                        ),
                      )
                      .toList(),
                ),
              ),
            ],
          ),
        ),
      ),
      floatingActionButton: StreamBuilder<bool>(
        stream: FlutterBlue.instance.isScanning,
        initialData: false,
        builder: (c, snapshot) {
          if (snapshot.data!) {
            return FloatingActionButton(
              child: Icon(Icons.stop),
              onPressed: () => FlutterBlue.instance.stopScan(),
              backgroundColor: Colors.red,
            );
          } else {
            return FloatingActionButton(
              child: Icon(Icons.search),
              onPressed: () async {
                await FlutterBlue.instance.startScan(timeout: Duration(seconds: 4));
              },
            );
          }
        },
      ),
    );
  }

  Future<void> _startScan() async {
    await FlutterBlue.instance.startScan(timeout: Duration(seconds: 4)).drain();
  }
}

class DeviceScreen extends StatelessWidget {
  const DeviceScreen({Key? key, required this.device}) : super(key: key);

  final BluetoothDevice device;

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(device.name),
        actions: <Widget>[
          StreamBuilder<BluetoothDeviceState>(
            stream: device.state,
            initialData: BluetoothDeviceState.connecting,
            builder: (c, snapshot) {
              VoidCallback? onPressed;
              String text;
              switch (snapshot.data) {
                case BluetoothDeviceState.connected:
                  onPressed = () => device.disconnect();
                  text = 'DISCONNECT';
                  break;
                case BluetoothDeviceState.disconnected:
                  onPressed = () => device.connect();
                  text = 'CONNECT';
                  break;
                default:
                  onPressed = null;
                  text = snapshot.data.toString().substring(21).toUpperCase();
                  break;
              }
              return ElevatedButton(
                  onPressed: onPressed,
                  child: Text(text));
            },
          )
        ],
      ),
      body: SingleChildScrollView(
        child: Column(
          children: <Widget>[
            StreamBuilder<BluetoothDeviceState>(
              stream: device.state,
              initialData: BluetoothDeviceState.connecting,
              builder: (c, snapshot) => ListTile(
                leading: (snapshot.data == BluetoothDeviceState.connected)
                    ? Icon(Icons.bluetooth_connected)
                    : Icon(Icons.bluetooth_disabled),
                title: Text('Device is ${snapshot.data.toString().split('.')[1]}.'),
                subtitle: Text('${device.id}'),
              ),
            ),
            StreamBuilder<List<BluetoothService>>(
              stream: device.services,
              initialData: [],
              builder: (c, snapshot) {
                if (snapshot.data == null) return Text('Empty');
                return Column(
                  children: snapshot.data!.map((service) {
                    return ListTile(
                      title: Text(service.uuid.toString()),
                    );
                  }).toList(),
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}