Flutter 前后台切换监听

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

import 'package:background_fetch/background_fetch.dart';

void main() {
  // Enable integration testing with the Flutter Driver extension.
  // See https://flutter.io/testing/ for more info.
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State
    with WidgetsBindingObserver{
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    print("--" + state.toString());
    switch (state) {
      case AppLifecycleState.inactive: // 处于这种状态的应用程序应该假设它们可能在任何时候暂停。
        break;
      case AppLifecycleState.resumed:// 应用程序可见，前台
        break;
      case AppLifecycleState.paused: // 应用程序不可见，后台
        break;
      case AppLifecycleState.suspending: // 申请将暂时暂停
        break;
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
            title: const Text('前后台测试')
        ),
        body: Container(
          color: Colors.black,
          child: Text('前后台测试'),
        ),
      ),
    );
  }
}