Flutterを使用して現在のGPS位置を取得する方法

このチュートリアルでは、Flutter アプリで現在の GPS 地理位置情報 (経度と緯度) を取得する方法を学びます。また、GPS 位置情報を聞く方法も示しました。経度と緯度が自動的に変化します。

まず、 pubspect.yaml ファイルに次の行を追加して、プロジェクトにgeolocator Flutter パッケージを追加する必要があります。

dependencies:
  flutter:
    sdk: flutter
  geolocator: ^8.0.0

android/app/src/main/AndroidManifest.xml にあるAndroidManifest.xmlファイルにこの権限を追加します。

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

輸入：

import 'package:geolocator/geolocator.dart';

GPS が有効になっているかどうかを確認する方法:

bool servicestatus = await Geolocator.isLocationServiceEnabled();

if(servicestatus){
   print("GPS service is enabled");
}else{
   print("GPS service is disabled.");
}

非同期メソッドを使用して、GPS サービスが有効か無効かを確認できます。 Geolocator.isLocationServiceEnabled();

位置情報の許可を確認または位置情報の許可をリクエストする方法:

LocationPermission permission = await Geolocator.checkPermission();

if (permission == LocationPermission.denied) {
    permission = await Geolocator.requestPermission();
    if (permission == LocationPermission.denied) {
        print('Location permissions are denied');
    }else if(permission == LocationPermission.deniedForever){
        print("'Location permissions are permanently denied");
    }else{
        print("GPS Location service is granted");
    }
}else{
    print("GPS Location permission granted.");
}

権限を確認するか Geolocator.checkPermission()、権限が付与されていない場合は権限を要求でき ますGeolocator.requestPermission()。

Position position = await Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
print(position.longitude); //Output: 80.24599079
print(position.latitude); //Output: 29.6593457

String long = position.longitude.toString();
String lat = position.latitude.toString();

を使用して、経度や緯度などの現在の GPS 位置を取得できます Geolocator.getCurrentPosition()。

GPS 位置情報を聞く方法: 経度と緯度の変化ストリーム:

import 'dart:async';

LocationSettings locationSettings = LocationSettings(
      accuracy: LocationAccuracy.high, //accuracy of the location data
      distanceFilter: 100, //minimum distance (measured in meters) a 
                            //device must move horizontally before an update event is generated;
);

StreamSubscription<Position> positionStream = Geolocator.getPositionStream(
      locationSettings: locationSettings).listen((Position position) {
      print(position.longitude); //Output: 80.24599079
      print(position.latitude); //Output: 29.6593457

      String long = position.longitude.toString();
      String lat = position.latitude.toString();
});

ここで、Geolocator は位置の変更に関するデータを自動的に送信します。 

Flutter/Dart アプリの完全なコード例:

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
     return MaterialApp(
         home: Home()
      );
  }
}

class Home extends  StatefulWidget {
  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {

  bool servicestatus = false;
  bool haspermission = false;
  late LocationPermission permission;
  late Position position;
       String long = "", lat = "";
  late StreamSubscription<Position> positionStream;

   @override
  void initState() {
    checkGps();
    super.initState();
  }

  checkGps() async {
      servicestatus = await Geolocator.isLocationServiceEnabled();
      if(servicestatus){
            permission = await Geolocator.checkPermission();
          
            if (permission == LocationPermission.denied) {
                permission = await Geolocator.requestPermission();
                if (permission == LocationPermission.denied) {
                    print('Location permissions are denied');
                }else if(permission == LocationPermission.deniedForever){
                    print("'Location permissions are permanently denied");
                }else{
                   haspermission = true;
                }
            }else{
               haspermission = true;
            }

            if(haspermission){
                setState(() {
                  //refresh the UI
                });

                getLocation();
            }
      }else{
        print("GPS Service is not enabled, turn on GPS location");
      }

      setState(() {
         //refresh the UI
      });
  }

  getLocation() async {
      position = await Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
      print(position.longitude); //Output: 80.24599079
      print(position.latitude); //Output: 29.6593457

      long = position.longitude.toString();
      lat = position.latitude.toString();

      setState(() {
         //refresh UI
      });

      LocationSettings locationSettings = LocationSettings(
            accuracy: LocationAccuracy.high, //accuracy of the location data
            distanceFilter: 100, //minimum distance (measured in meters) a 
                                 //device must move horizontally before an update event is generated;
      );

      StreamSubscription<Position> positionStream = Geolocator.getPositionStream(
            locationSettings: locationSettings).listen((Position position) {
            print(position.longitude); //Output: 80.24599079
            print(position.latitude); //Output: 29.6593457

            long = position.longitude.toString();
            lat = position.latitude.toString();

            setState(() {
              //refresh UI on update
            });
      });
  }

  @override
  Widget build(BuildContext context) {
   
    return Scaffold(
         appBar: AppBar(
            title: Text("Get GPS Location"),
            backgroundColor: Colors.redAccent
         ),
          body: Container(
            alignment: Alignment.center,
            padding: EdgeInsets.all(50),
             child: Column(
                children: [ 

                     Text(servicestatus? "GPS is Enabled": "GPS is disabled."),
                     Text(haspermission? "GPS is Enabled": "GPS is disabled."),
                     
                     Text("Longitude: $long", style:TextStyle(fontSize: 20)),
                     Text("Latitude: $lat", style: TextStyle(fontSize: 20),)

                ]
              )
          )
    );
  } 
}

このようにして、Flutter アプリで現在の GPS 位置を取得したり、GPS 位置の変化を継続的にリッスンしたりできます。