ble get_it textfile (html stripped <> chars>
// example of ble using get_it plugin

////////////main.dart///////////////////
import 'package:ble_demo/app_model.dart';
import 'package:flutter/material.dart';
import 'package:get_it/get_it.dart';
import './ble.dart';

GetIt getIt = GetIt.instance;

void main() {
  getIt.registerSingleton(AppModelImplementation(),
    signalsReady: true);
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage());}}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();}
class _MyHomePageState extends State {

  BLE ble = BLE();

  @override  
  void initState() {
    getIt.isReady()
      .then((_) => getIt().addListener(update));
    super.initState();
    ble.init();}

  @override  
  void dispose(){
    getIt().removeListener(update);
    super.dispose();}

  update() => setState(() => {});

  @override  
  Widget build(BuildContext ctx) {
    var data = getIt().data;
    return Scaffold( 
      appBar: AppBar(title: Text("ble with get it plugin")), 
      body: Text("received: $data",   // show anything coming in from notify characteristic
        style: TextStyle(color: Colors.black)),);}}  
      
///////////ble.dart////////////////////////////////////////
import 'package:flutter_blue/flutter_blue.dart';
import './main.dart';
import 'dart:async';
import './app_model.dart';

class BLE {

  BLE();

  static BluetoothCharacteristic txChar;
  static BluetoothCharacteristic notifyChar;
  static String receivedText;

  static final String baseUuid = "-b5a3-f393-e0a9-e50e24dcca9e";
  final String serviceUuid = "6e400001" + baseUuid;
  final String txCharUuid = "6e400002" + baseUuid;
  final String notifyCharUuid = "6e400003" + baseUuid;  
  final String deviceName = "Adafruit Bluefruit LE";

  FlutterBlue flutterBlue = FlutterBlue.instance;
  StreamSubscription scanSubScription;

  BluetoothDevice targetDevice;

    init(){
    scanSubScription = flutterBlue.scan().listen((scanResult) {
      if (scanResult.device.name == deviceName) {
        stopScan();
        targetDevice = scanResult.device;
        connectToDevice();
      }
    }, onDone: () => stopScan());}

  stopScan() {
    scanSubScription?.cancel();
    scanSubScription = null;}

  connectToDevice() async {
    if (targetDevice == null) return;
    await targetDevice.connect();
    print("device connectd");
    discoverServices();}

  disconnectFromDevice() {
    if (targetDevice == null) return;
    targetDevice.disconnect();}

  discoverServices() async {
    print("discoverservices func");
    if (targetDevice == null) return;
    List services = await targetDevice.discoverServices();
    services.forEach((service) {
      if (service.uuid.toString() == serviceUuid) {
        service.characteristics.forEach((characteristic) {

          if (characteristic.uuid.toString() == notifyCharUuid) {
            notifyChar = characteristic;
            characteristic.setNotifyValue(true);
            characteristic.value.listen((v){
              if (v.isNotEmpty) {
                getIt().setData(String.fromCharCodes(v));}});}

          if (characteristic.uuid.toString() == txCharUuid) {
            print("found txchar");
            txChar = characteristic;}});}});}}

///////////app_model.dart
// example straight from get_it repository
import 'package:flutter/material.dart';
import 'main.dart';

abstract class AppModel extends ChangeNotifier {
  void setData(String s);
  String get data;
}

class AppModelImplementation extends AppModel {
  String _data = "";

  AppModelImplementation() {
    /// lets pretend we have to do some async initilization
    Future.delayed(Duration(seconds: 1)).then((_) => getIt.signalReady(this));}

  @override
  String get data => _data;

  @override
  void setData(String s) {
    _data = s;
    notifyListeners();}}