Flutter 蓝牙插件 bluetooth_low_energy 使用说明

bluetooth_low_energy 蓝牙插件使用说明

文档介绍了在Flutter使用bluetooth_low_energy插件监听蓝牙状态，扫描蓝牙设备，连接蓝牙设备，订阅蓝牙消息等功能。

1. 引入插件

dependencies:
	bluetooth_low_energy: ^6.0.2

2.初始化中心设备

import 'package:bluetooth_low_energy/bluetooth_low_energy.dart';

// 中心设备实例
final CentralManager centralManager = CentralManager();
// 符合特点的蓝牙设备
String deviceNameReg = ""; 
// 自定义蓝牙设备列表
List<CustomBlutooth> devices = [];

/// 设备扫描
discovered = centralManager.discovered.listen((DiscoveredEventArgs event){
      final Advertisement advertisement = event.advertisement;
      String name = advertisement.name ?? "";
      // 使用name查找符合条件的设备
      if(name.isNotEmpty && name.toUpperCase().startsWith(deviceNameReg)){
        // 添加进 devices
      }
});

/// 监听设备蓝牙状态
stateChanged = centralManager.stateChanged.listen((BluetoothLowEnergyStateChangedEventArgs event){
      if(BluetoothLowEnergyState.poweredOn == event.state){
        // 蓝牙状态正常，开始扫描
      }else{
        // 清空 devices
      }
});

/// 连接状态回调
connectionStateChanged = centralManager.connectionStateChanged.listen((PeripheralConnectionStateChangedEventArgs event){
      CustomBlutooth? select = devices.firstWhereOrNull((device)=>device.peripheral == event.peripheral);
      if(select != null){
        if(event.state == ConnectionState.connected){
          // 连接成功、更改连接状态、订阅通知
        }else{
          // 标记设备连接状态
        }
      }
});

/// 订阅消息回调
characteristicNotified = centralManager.characteristicNotified.listen((GATTCharacteristicNotifiedEventArgs event){
  final Uint8List text = event.value;
  CustomBlutooth? select = devices.firstWhereOrNull((device)=>device.peripheral == event.peripheral);
  if(select != null){
    // 转码接收信息
    int? value = int.tryParse(
        String.fromCharCodes(text.toList()).replaceAll("\r\n", "")
    );
    // 添加蓝牙数据
    if(value is int){
      select.setValue(value);
    }
  }
});

3.启动程序

bool state = await centralManager.authorize();
if(state){
  if(centralManager.state != BluetoothLowEnergyState.poweredOn){
    // 蓝牙未打开
  }else{
	// 蓝牙正常 开始扫描
    centralManager.startDiscovery();
  }
}else{
  // 没有蓝牙权限
}

4.连接蓝牙

// 一般定义在 CustomBlutooth 中，内部维护连接状态等蓝牙数据

// 查看是否在已连接
List<Peripheral> list = await centralManager.retrieveConnectedPeripherals();
if(list.firstWhereOrNull((d)=>d == peripheral) != null){
   // 已在连接中
}else{
   	// 连接断开 -再次连接
    // Timer - 定义超时处理
    try{
      	await centralManager.connect(peripheral);
    } on PlatformException catch(error){
		// 连接出错
    }
}

5.订阅蓝牙消息

// 蓝牙设备连接成功后，订阅消息

// 订阅特征 -这里连接满足deviceNameReg特征的设备
const Map BLE_CONFIG = {
  serviceId: "XXXX",
  characteristicId: "XXXX"
};

List<GATTService> services = await centralManager.discoverGATT(peripheral);
GATTService? service;
GATTCharacteristic? characteristic;
for (var element in services) {
  if(element.uuid == UUID.fromString(BLE_CONFIG["serviceId"])){
    service = element;
    characteristic = element
        .characteristics
        .toList()
        .firstWhereOrNull((tag)=>tag.uuid == UUID.fromString(BLE_CONFIG["characteristicId"]));
  }
}
if(service != null && characteristic != null){
  // 订阅成功后就能接收到消息了
  centralManager.setCharacteristicNotifyState(peripheral, characteristic, state: true);
}