Question

我正在尝试让我的 Flutter 应用程序显示我的当前位置。虽然调试控制台中显示的代码没有错误，但模拟器只是继续加载而不显示任何结果。我怀疑有某种形式的异步暂停正在发生，但不知道如何解决。

这是我用来获取当前位置的文件 (geolocator_services.dart)：

import 'package:geolocator/geolocator.dart';

class GeolocatorService {
  Future<Position> getCurrentLocation() async {
    return await Geolocator.getCurrentPosition(
      desiredAccuracy: LocationAccuracy.high
    );
  }
}

这是我用来存储我的位置数据的文件 (application_bloc.dart)

import 'package:flutter/material.dart';
import 'package:hawkepedia/services/geolocator_Services.dart';

import 'package:geolocator/geolocator.dart';

class ApplicationBloc with ChangeNotifier {
  final geoLocatorService = GeolocatorService();

  //Variables
  Position? currentLocation;

  //fire function when the app starts
  ApplicationBloc(){
    setCurrentLocation();
  }

  //gets current location
  setCurrentLocation() async {
    currentLocation = await geoLocatorService.getCurrentLocation();
    notifyListeners();
  }
}

这是我用来在我的应用 (maps_mainpage.dart) 中显示地理位置数据的文件。

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:hawkepedia/blocs/application_bloc.dart';
import 'package:provider/provider.dart';
class MainMaps extends StatefulWidget {
  const MainMaps({ Key? key }) : super(key: key);

  @override
  _MainMapsState createState() => _MainMapsState();
}

class _MainMapsState extends State<MainMaps> {
  @override
  Widget build(BuildContext context) {
    final applicationBloc = Provider.of<ApplicationBloc>(context);
    return Scaffold(
      //if this is the first time loading the app
      body: (applicationBloc.currentLocation == null)
        ? Center(child: CircularProgressIndicator(),)
        : ListView(
          children: [
            TextField(
              decoration: InputDecoration(hintText: 'Search Location'),
            ),
              Container(
                height: 300.0,
                child: GoogleMap(
                  mapType: MapType.normal,
                  myLocationButtonEnabled: true,
                  initialCameraPosition:
                    CameraPosition(target: LatLng(applicationBloc.currentLocation!.latitude, 
                    applicationBloc.currentLocation!.longitude),
                    zoom: 14),
                ),
              )
          ],
        ),
    );
  }
}

Answer 1

将您的 Scaffold 包装到 Consumer 小部件中，确保您还使用相关提供程序小部件包装了 MaterialApp 以便使用它。

     late final applicationBloc;  
     @override
      void initState() {
        super.initState();
         applicationBloc=  Provider.of<ApplicationBloc>(context);   
       applicationBloc.setCurrentLocation();
      }

那么，

 Consumer(builder:(context,child) {
  return Scaffold(
      //if this is the first time loading the app
      body: (applicationBloc.currentLocation == null)
        ? Center(child: CircularProgressIndicator(),)
        : ListView(
          children: [
            TextField(
              decoration: InputDecoration(hintText: 'Search Location'),
            ),
              Container(
                height: 300.0,
                child: GoogleMap(
                  mapType: MapType.normal,
                  myLocationButtonEnabled: true,
                  initialCameraPosition:
                    CameraPosition(target: LatLng(applicationBloc.currentLocation!.latitude, 
                    applicationBloc.currentLocation!.longitude),
                    zoom: 14),
                ),
              )
          ],
        ),
    );
  }
});

Answer 2

在调用 Geolocator.getCurrentPosition() 之前，我们需要检查位置服务是否已启用以及我们是否有位置权限。

bool enabled = await Geolocator.isLocationServiceEnabled();
if (!enabled) {
  //do something
  return;
}

LocationPermission permission = await Geolocator.checkPermission();

if (permission == LocationPermission.denied) {
  //do something
  return;
}

if (permission == LocationPermission.deniedForever) {
  // Permissions are denied forever, handle appropriately.      
  AppSettings.openLocationSettings();
  return;
}

try {
  _position = await Geolocator.getCurrentPosition();      
} catch (e) {
  
}

Answer 3

试试这个然后告诉我 maps_mainpage.dart

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:hawkepedia/blocs/application_bloc.dart';
import 'package:provider/provider.dart';
import 'package:untitled/export.dart';

class MainMaps extends StatefulWidget {
  const MainMaps({Key? key}) : super(key: key);

  @override
  _MainMapsState createState() => _MainMapsState();
}

class _MainMapsState extends State<MainMaps> {
  late final applicationBloc;
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    applicationBloc = Provider.of<ApplicationBloc>(context);
  }

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
      create: (_) => ApplicationBloc(),
      child: Consumer<ApplicationBloc>(builder: (context, value, child) {
        return Scaffold(
          //if this is the first time loading the app
          body: (value.currentLocation == null)
              ? Center(
                  child: CircularProgressIndicator(),
                )
              : ListView(
                  children: [
                    TextField(
                      decoration: InputDecoration(hintText: 'Search Location'),
                    ),
                    Container(
                      height: 300.0,
                      child: GoogleMap(
                        mapType: MapType.normal,
                        myLocationButtonEnabled: true,
                        initialCameraPosition: CameraPosition(
                            target: LatLng(
                                applicationBloc.currentLocation!.latitude,
                                applicationBloc.currentLocation!.longitude),
                            zoom: 14),
                      ),
                    )
                  ],
                ),
        );
      }),
    );
  }
}

Flutter 异步暂停

3 个答案: