将异步数据(GPS协调)从FutureBuilder传递到提供程序/设置异步构造函数

class GPSData {
  final double latitude;
  final double longitude;

  GPSData({required this.latitude, required this.longitude});
}

import 'package:flutter/foundation.dart';

class GPSProvider extends ChangeNotifier {
  Future<GPSData> getGPSData() async {
    // 模拟异步获取GPS数据的过程
    await Future.delayed(Duration(seconds: 2));

    // 假设获取到了GPS数据
    GPSData gpsData = GPSData(latitude: 123.456, longitude: 789.012);

    // 通知监听者数据已更新
    notifyListeners();

    return gpsData;
  }
}

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class MyPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<GPSData>(
      future: Provider.of<GPSProvider>(context, listen: false).getGPSData(),
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return CircularProgressIndicator();
        } else if (snapshot.hasError) {
          return Text('Error: ${snapshot.error}');
        } else {
          // 获取到了异步数据
          GPSData gpsData = snapshot.data!;

          // 将异步数据传递给提供程序
          Provider.of<GPSProvider>(context, listen: false).setGPSData(gpsData);

          return Text('Latitude: ${gpsData.latitude}, Longitude: ${gpsData.longitude}');
        }
      },
    );
  }
}

class GPSProvider extends ChangeNotifier {
  GPSData? _gpsData;

  Future<GPSData> getGPSData() async {
    // ...
  }

  void setGPSData(GPSData gpsData) {
    _gpsData = gpsData;
    notifyListeners();
  }

  GPSData? get gpsData => _gpsData;
}

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class AnotherPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    GPSData? gpsData = Provider.of<GPSProvider>(context).gpsData;

    if (gpsData != null) {
      return Text('Latitude: ${gpsData.latitude}, Longitude: ${gpsData.longitude}');
    } else {
      return CircularProgressIndicator();
    }
  }
}