Flutter后台定位插件background_location的使用

background_location 是一个用于在后台获取位置更新的Flutter插件，支持Android和iOS（要求iOS 10.0+）。它在iOS上使用CoreLocation，在Android上使用FusedLocationProvider。

Getting Started

1. 添加依赖到 pubspec.yaml

dependencies:
  background_location: ^0.13.0

2. 安装包

从命令行安装：

$ flutter packages get

或者使用编辑器自带的支持flutter packages get功能。

如何使用

导入包

import 'package:background_location/background_location.dart';

请求权限

你可以使用 permission_handler 来请求用户权限。

设置通知标题、消息和图标 (仅限Android)

BackgroundLocation.setAndroidNotification(
  title: "Notification title",
  message: "Notification message",
  icon: "@mipmap/ic_launcher",
);

设置定位间隔 (仅限Android)

BackgroundLocation.setAndroidConfiguration(1000);

启动定位服务

BackgroundLocation.stopLocationService(); // 确保之前启动的服务已停止
BackgroundLocation.startLocationService();

使用 distanceFilter

BackgroundLocation.startLocationService(distanceFilter: 10);

强制使用 LocationManager

BackgroundLocation.startLocationService(forceAndroidLocationManager: true);

获取位置更新

BackgroundLocation.getLocationUpdates((location) {
  print(location);
});

位置数据类属性：

double latitude;
double longitude;
double altitude;
double bearing;
double accuracy;
double speed;
double time;
bool isMock;

停止监听位置变化

BackgroundLocation.stopLocationService();

确保在 Android 和 iOS 应用中声明所有必要的权限。

info.plist (iOS)

<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string>This app needs access to location.</string>
<key>NSLocationAlwaysUsageDescription</key>
<string>This app needs access to location.</string>
<key>NSLocationWhenInUseUsageDescription</key>
<string>This app needs access to location.</string>
<key>UIBackgroundModes</key>
<array>
    <string>fetch</string>
    <string>location</string>
</array>

AndroidManifest.xml (Android)

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

示例代码

以下是一个完整的示例应用程序：

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

void main() => runApp(MyApp());

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

class _MyAppState extends State<MyApp> {
  String latitude = 'waiting...';
  String longitude = 'waiting...';
  String altitude = 'waiting...';
  String accuracy = 'waiting...';
  String bearing = 'waiting...';
  String speed = 'waiting...';
  String time = 'waiting...';
  bool? serviceRunning = null;

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Background Location Service'),
        ),
        body: Center(
          child: ListView(
            children: <Widget>[
              locationData('Latitude: ' + latitude),
              locationData('Longitude: ' + longitude),
              locationData('Altitude: ' + altitude),
              locationData('Accuracy: ' + accuracy),
              locationData('Bearing: ' + bearing),
              locationData('Speed: ' + speed),
              locationData('Time: ' + time),
              locationData('IsServiceRunning: ' + serviceRunning.toString()),
              ElevatedButton(
                  onPressed: () async {
                    await BackgroundLocation.setAndroidNotification(
                      title: 'Background service is running',
                      message: 'Background location in progress',
                      icon: '@mipmap/ic_launcher',
                    );
                    await BackgroundLocation.startLocationService(
                        distanceFilter: 20);
                    BackgroundLocation.getLocationUpdates((location) {
                      setState(() {
                        latitude = location.latitude.toString();
                        longitude = location.longitude.toString();
                        accuracy = location.accuracy.toString();
                        altitude = location.altitude.toString();
                        bearing = location.bearing.toString();
                        speed = location.speed.toString();
                        time = DateTime.fromMillisecondsSinceEpoch(
                                location.time!.toInt())
                            .toString();
                      });
                      print('''\n
                        Latitude:  $latitude
                        Longitude: $longitude
                        Altitude: $altitude
                        Accuracy: $accuracy
                        Bearing:  $bearing
                        Speed: $speed
                        Time: $time
                        IsServiceRunning: $serviceRunning
                      ''');
                    });
                  },
                  child: Text('Start Location Service')),
              ElevatedButton(
                  onPressed: () {
                    BackgroundLocation.stopLocationService();
                  },
                  child: Text('Stop Location Service')),
              ElevatedButton(
                  onPressed: () {
                    BackgroundLocation.isServiceRunning().then((value) {
                      setState(() {
                        serviceRunning = value;
                      });
                      print("Is Running: $value");
                    });
                  },
                  child: Text('Check service')),
              ElevatedButton(
                  onPressed: () {
                    getCurrentLocation();
                  },
                  child: Text('Get Current Location')),
            ],
          ),
        ),
      ),
    );
  }

  Widget locationData(String data) {
    return Text(
      data,
      style: TextStyle(
        fontWeight: FontWeight.bold,
        fontSize: 18,
      ),
      textAlign: TextAlign.center,
    );
  }

  void getCurrentLocation() {
    BackgroundLocation().getCurrentLocation().then((location) {
      print('This is current Location ' + location.toMap().toString());
    });
  }

  @override
  void dispose() {
    BackgroundLocation.stopLocationService();
    super.dispose();
  }
}

这个示例展示了如何使用 background_location 插件来获取后台位置更新，并在界面上显示这些位置信息。