Flutter地理位置获取插件location的使用

简介

location插件用于在Flutter应用中获取设备的地理位置信息。它支持Android和iOS平台，并提供了当位置变化时的回调功能。此外，该插件还支持后台模式下的位置获取。

开始使用

添加依赖

首先，在pubspec.yaml文件中添加location依赖：

dependencies:
  location: ^5.0.0

平台配置

Android

为了在Android上使用后台模式的位置服务，需要在AndroidManifest.xml中添加以下权限：

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

同时提醒用户在设置中将位置权限设置为“始终允许”。

iOS

在Info.plist中添加必要的权限描述：

<key>NSLocationWhenInUseUsageDescription</key>
<string>We need your location to provide better service.</string>
<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string>We need your location even when you're not using the app.</string>

如果需要接收后台位置更新，还需添加：

<key>UIBackgroundModes</key>
<array>
  <string>location</string>
</array>

Web 和 macOS

• Web: 插件开箱即用，无需额外配置。
• macOS: 需要在Xcode中启用沙盒并选择“Location”选项，同时在Info.plist中添加相应的权限描述。

使用方法

导入包：

import 'package:location/location.dart';

获取单次位置

Location location = Location();

bool _serviceEnabled;
PermissionStatus _permissionGranted;
LocationData _locationData;

_serviceEnabled = await location.serviceEnabled();
if (!_serviceEnabled) {
  _serviceEnabled = await location.requestService();
  if (!_serviceEnabled) {
    return;
  }
}

_permissionGranted = await location.hasPermission();
if (_permissionGranted == PermissionStatus.denied) {
  _permissionGranted = await location.requestPermission();
  if (_permissionGranted != PermissionStatus.granted) {
    return;
  }
}

_locationData = await location.getLocation();
print('纬度: ${_locationData.latitude}, 经度: ${_locationData.longitude}');

监听位置变化

location.onLocationChanged.listen((LocationData currentLocation) {
  print('当前位置更新 - 纬度: ${currentLocation.latitude}, 经度: ${currentLocation.longitude}');
});

启用后台模式

await location.enableBackgroundMode(enable: true);

示例代码

下面是一个完整的示例应用程序，展示了如何集成和使用location插件：

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Location Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Location Example'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  final Location location = Location();
  bool _serviceEnabled = false;
  PermissionStatus? _permissionGranted;
  LocationData? _locationData;

  Future<void> _getLocation() async {
    _serviceEnabled = await location.serviceEnabled();
    if (!_serviceEnabled) {
      _serviceEnabled = await location.requestService();
      if (!_serviceEnabled) {
        return;
      }
    }

    _permissionGranted = await location.hasPermission();
    if (_permissionGranted == PermissionStatus.denied) {
      _permissionGranted = await location.requestPermission();
      if (_permissionGranted != PermissionStatus.granted) {
        return;
      }
    }

    _locationData = await location.getLocation();
    setState(() {});
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('位置信息：'),
            Text(
              _locationData == null
                  ? '正在获取...'
                  : '纬度: ${_locationData!.latitude}, 经度: ${_locationData!.longitude}',
              style: TextStyle(fontSize: 24),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: _getLocation,
              child: Text('刷新位置'),
            ),
          ],
        ),
      ),
    );
  }
}

以上代码创建了一个简单的Flutter应用，展示了如何请求位置权限、检查服务状态以及获取当前位置。通过点击按钮可以刷新位置信息。