Flutter地理位置服务插件geos的使用

geos 是一个用于处理地理信息的Flutter插件，它提供了一些有用的类来处理国家和地区的信息。下面我们将详细介绍如何使用这个插件，并提供一个完整的示例demo。

特性

• Country 枚举：可以轻松创建一个国家对象并访问其相关信息。
• Place 类：可以创建一个地点对象，包含地址、经纬度、名称、是否为收藏地点以及标签等信息。

示例代码

以下是一个简单的示例，展示了如何使用 geos 插件中的 Country 和 Place 类：

import 'dart:collection';
import 'package:geos/geos.dart';

void main() {
  // 使用 Country 枚举
  const Country italy = Country.italy;
  print('Country Alpha2 Code: ${italy.alpha2Code}'); // 输出: IT
  print('Country Alpha3 Code: ${italy.alpha3Code}'); // 输出: ITA
  print('Country English Name: ${italy.englishName}'); // 输出: Italy
  print('Country Flag Emoji: ${italy.flagEmoji}'); // 输出: 🇮🇹
  print('Country Numeric Code: ${italy.numericCode}'); // 输出: 380

  // 创建 Place 对象
  final Place myPlace = Place(
    address: 'This is the address 1',
    latitude: 10.1234567,
    longitude: 15.1234567,
    name: 'The name of this place 1',
    tags: SplayTreeSet.from([
      'tag1',
      'tag2',
      'tag3',
    ]),
  );

  final Place myFavoritePlace = Place(
    address: 'This is the address 2',
    isFavorite: true,
    latitude: 0.1,
    longitude: 0.5,
    name: 'The name of this place 2',
    tags: SplayTreeSet.from([
      'tag1',
      'tag2',
      'tag3',
    ]),
  );

  // 计算两个地点之间的距离
  final double distance = myPlace.distanceWGS84(myFavoritePlace);
  print('Distance between places: $distance km');
}

完整的示例Demo

为了更好地理解如何在Flutter应用中使用 geos 插件，这里提供一个更完整的示例，包括如何在Flutter UI中展示这些信息。

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

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Geos Plugin Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  [@override](/user/override)
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late String countryInfo;
  late String placeInfo;
  late String distanceInfo;

  [@override](/user/override)
  void initState() {
    super.initState();
    loadCountryAndPlaceInfo();
  }

  void loadCountryAndPlaceInfo() {
    const Country italy = Country.italy;
    final Place myPlace = Place(
      address: 'This is the address 1',
      latitude: 10.1234567,
      longitude: 15.1234567,
      name: 'The name of this place 1',
      tags: SplayTreeSet.from(['tag1', 'tag2', 'tag3']),
    );

    final Place myFavoritePlace = Place(
      address: 'This is the address 2',
      isFavorite: true,
      latitude: 0.1,
      longitude: 0.5,
      name: 'The name of this place 2',
      tags: SplayTreeSet.from(['tag1', 'tag2', 'tag3']),
    );

    setState(() {
      countryInfo = '''
Country Info:
Alpha2 Code: ${italy.alpha2Code}
Alpha3 Code: ${italy.alpha3Code}
English Name: ${italy.englishName}
Flag Emoji: ${italy.flagEmoji}
Numeric Code: ${italy.numericCode}
''';

      placeInfo = '''
Place Info:
Address: ${myPlace.address}
Latitude: ${myPlace.latitude}
Longitude: ${myPlace.longitude}
Name: ${myPlace.name}
Tags: ${myPlace.tags.join(', ')}
''';

      final double distance = myPlace.distanceWGS84(myFavoritePlace);
      distanceInfo = 'Distance between places: $distance km';
    });
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Geos Plugin Demo'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(countryInfo),
            SizedBox(height: 20),
            Text(placeInfo),
            SizedBox(height: 20),
            Text(distanceInfo),
          ],
        ),
      ),
    );
  }
}