【Flutter】ビーコン信号の受信を行う方法ご紹介。

dependencies:
  flutter_beacon: ^0.3.0

import 'dart:io';
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter/services.dart';
import 'package:flutter_beacon/flutter_beacon.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
final StreamController<BluetoothState> streamController = StreamController();
StreamSubscription<BluetoothState> _streamBluetooth;
StreamSubscription<RangingResult> _streamRanging;
final _regionBeacons = <Region, List<Beacon>>{};
final _beacons = <Beacon>[];
bool authorizationStatusOk = false;
bool locationServiceEnabled = false;
bool bluetoothEnabled = false;
@override
void initState() {
WidgetsBinding.instance.addObserver(this);
super.initState();
listeningState();
}
listeningState() async {
print('Listening to bluetooth state');
_streamBluetooth = flutterBeacon
.bluetoothStateChanged()
.listen((BluetoothState state) async {
print('BluetoothState = $state');
streamController.add(state);
switch (state) {
case BluetoothState.stateOn:
initScanBeacon();
break;
case BluetoothState.stateOff:
await pauseScanBeacon();
await checkAllRequirements();
break;
}
});
}
checkAllRequirements() async {
final bluetoothState = await flutterBeacon.bluetoothState;
final bluetoothEnabled = bluetoothState == BluetoothState.stateOn;
final authorizationStatus = await flutterBeacon.authorizationStatus;
final authorizationStatusOk =
authorizationStatus == AuthorizationStatus.allowed ||
authorizationStatus == AuthorizationStatus.always;
final locationServiceEnabled =
await flutterBeacon.checkLocationServicesIfEnabled;
setState(() {
this.authorizationStatusOk = authorizationStatusOk;
this.locationServiceEnabled = locationServiceEnabled;
this.bluetoothEnabled = bluetoothEnabled;
});
}
initScanBeacon() async {
await flutterBeacon.initializeScanning;
await checkAllRequirements();
if (!authorizationStatusOk ||
!locationServiceEnabled ||
!bluetoothEnabled) {
print('RETURNED, authorizationStatusOk=$authorizationStatusOk, '
'locationServiceEnabled=$locationServiceEnabled, '
'bluetoothEnabled=$bluetoothEnabled');
return;
}
final regions = <Region>[
Region(
identifier: 'Cubeacon',
proximityUUID: '[使用するビーコンのUUID]',
),
];
if (_streamRanging != null) {
if (_streamRanging.isPaused) {
_streamRanging.resume();
return;
}
}
_streamRanging =
flutterBeacon.ranging(regions).listen((RangingResult result) {
print(result);
if (result != null && mounted) {
setState(() {
_regionBeacons[result.region] = result.beacons;
_beacons.clear();
_regionBeacons.values.forEach((list) {
_beacons.addAll(list);
});
_beacons.sort(_compareParameters);
});
}
});
}
pauseScanBeacon() async {
_streamRanging?.pause();
if (_beacons.isNotEmpty) {
setState(() {
_beacons.clear();
});
}
}
int _compareParameters(Beacon a, Beacon b) {
int compare = a.proximityUUID.compareTo(b.proximityUUID);
if (compare == 0) {
compare = a.major.compareTo(b.major);
}
if (compare == 0) {
compare = a.minor.compareTo(b.minor);
}
return compare;
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) async {
print('AppLifecycleState = $state');
if (state == AppLifecycleState.resumed) {
if (_streamBluetooth != null && _streamBluetooth.isPaused) {
_streamBluetooth.resume();
}
await checkAllRequirements();
if (authorizationStatusOk && locationServiceEnabled && bluetoothEnabled) {
await initScanBeacon();
} else {
await pauseScanBeacon();
await checkAllRequirements();
}
} else if (state == AppLifecycleState.paused) {
_streamBluetooth?.pause();
}
}
@override
void dispose() {
WidgetsBinding.instance.removeObserver(this);
streamController?.close();
_streamRanging?.cancel();
_streamBluetooth?.cancel();
flutterBeacon.close;
super.dispose();
}
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
brightness: Brightness.light,
primaryColor: Colors.white,
),
darkTheme: ThemeData(
brightness: Brightness.dark,
),
home: Scaffold(
appBar: AppBar(
title: const Text('Flutter Beacon'),
centerTitle: false,
actions: <Widget>[
if (!authorizationStatusOk)
IconButton(
icon: Icon(Icons.portable_wifi_off),
color: Colors.red,
onPressed: () async {
await flutterBeacon.requestAuthorization;
}),
if (!locationServiceEnabled)
IconButton(
icon: Icon(Icons.location_off),
color: Colors.red,
onPressed: () async {
if (Platform.isAndroid) {
await flutterBeacon.openLocationSettings;
} else if (Platform.isIOS) {
}
}),
StreamBuilder<BluetoothState>(
builder: (context, snapshot) {
if (snapshot.hasData) {
final state = snapshot.data;
if (state == BluetoothState.stateOn) {
return IconButton(
icon: Icon(Icons.bluetooth_connected),
onPressed: () {},
color: Colors.lightBlueAccent,
);
}
if (state == BluetoothState.stateOff) {
return IconButton(
icon: Icon(Icons.bluetooth),
onPressed: () async {
if (Platform.isAndroid) {
try {
await flutterBeacon.openBluetoothSettings;
} on PlatformException catch (e) {
print(e);
}
} else if (Platform.isIOS) {
}
},
color: Colors.red,
);
}
return IconButton(
icon: Icon(Icons.bluetooth_disabled),
onPressed: () {},
color: Colors.grey,
);
}
return SizedBox.shrink();
},
stream: streamController.stream,
initialData: BluetoothState.stateUnknown,
),
],
),
body: _beacons == null || _beacons.isEmpty
? Center(child: CircularProgressIndicator())
: ListView(
children: ListTile.divideTiles(
context: context,
tiles: _beacons.map((beacon) {
return ListTile(
title: Text(beacon.proximityUUID),
subtitle: new Row(
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Flexible(
child: Text(
'Major: ${beacon.major}\nMinor: ${beacon.minor}',
style: TextStyle(fontSize: 13.0)),
flex: 1,
fit: FlexFit.tight),
Flexible(
child: Text(
'Accuracy: ${beacon.accuracy}m\nRSSI: ${beacon.rssi}',
style: TextStyle(fontSize: 13.0)),
flex: 2,
fit: FlexFit.tight)
],
),
);
})).toList(),
),
),
);
}
}