当然，下面是一个关于如何使用Flutter地理编码插件google_geocoding_api的示例代码。这个示例展示了如何进行正向地理编码（根据地址获取经纬度）和反向地理编码（根据经纬度获取地址）。

首先，确保你已经在pubspec.yaml文件中添加了google_geocoding_api依赖：

dependencies:
  flutter:
    sdk: flutter
  google_geocoding_api: ^^最新版本号  # 请替换为最新的版本号

然后，运行flutter pub get来安装依赖。

接下来，创建一个Flutter应用，并在其中使用google_geocoding_api插件。以下是一个简单的示例：

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Google Geocoding API Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: GeocodingDemo(),
    );
  }
}

class GeocodingDemo extends StatefulWidget {
  @override
  _GeocodingDemoState createState() => _GeocodingDemoState();
}

class _GeocodingDemoState extends State<GeocodingDemo> {
  String _address = '';
  String _latitude = '';
  String _longitude = '';
  String _result = '';

  final Geocoding _geocoding = Geocoding(apiKey: 'YOUR_GOOGLE_MAPS_API_KEY'); // 请替换为你的Google Maps API Key

  void _performForwardGeocoding() async {
    try {
      List<Placemark> placemarks = await _geocoding.placemarkFromAddress(_address);

      Placemark place = placemarks.isNotEmpty ? placemarks[0] : null;
      if (place != null) {
        setState(() {
          _latitude = place.position.latitude.toString();
          _longitude = place.position.longitude.toString();
          _result = 'Address: ${place.locality}, ${place.postalCode}, ${place.country}';
        });
      }
    } catch (e) {
      setState(() {
        _result = 'Error: $e';
      });
    }
  }

  void _performReverseGeocoding() async {
    try {
      List<Placemark> placemarks = await _geocoding.placemarkFromCoordinates(
        double.parse(_latitude),
        double.parse(_longitude),
      );

      Placemark place = placemarks.isNotEmpty ? placemarks[0] : null;
      if (place != null) {
        setState(() {
          _address = '${place.thoroughfare}, ${place.subThoroughfare}, ${place.locality}, ${place.postalCode}, ${place.country}';
          _result = 'Coordinates: $_latitude, $_longitude\nAddress: $_address';
        });
      }
    } catch (e) {
      setState(() {
        _result = 'Error: $e';
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Google Geocoding API Demo'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            TextField(
              decoration: InputDecoration(labelText: 'Address'),
              onChanged: (value) {
                setState(() {
                  _address = value;
                });
              },
            ),
            SizedBox(height: 16),
            ElevatedButton(
              onPressed: _address.isNotEmpty ? _performForwardGeocoding : null,
              child: Text('Forward Geocoding'),
            ),
            SizedBox(height: 16),
            TextField(
              decoration: InputDecoration(labelText: 'Latitude'),
              keyboardType: TextInputType.number,
              onChanged: (value) {
                setState(() {
                  _latitude = value;
                });
              },
            ),
            SizedBox(height: 8),
            TextField(
              decoration: InputDecoration(labelText: 'Longitude'),
              keyboardType: TextInputType.number,
              onChanged: (value) {
                setState(() {
                  _longitude = value;
                });
              },
            ),
            SizedBox(height: 16),
            ElevatedButton(
              onPressed: (_latitude.isNotEmpty && _longitude.isNotEmpty)
                  ? _performReverseGeocoding
                  : null,
              child: Text('Reverse Geocoding'),
            ),
            SizedBox(height: 24),
            Text(_result, style: TextStyle(fontSize: 16)),
          ],
        ),
      ),
    );
  }
}

在这个示例中，我们创建了一个简单的Flutter应用，用户可以在界面上输入地址或经纬度坐标，然后分别触发正向地理编码和反向地理编码操作。结果会显示在界面的文本区域中。

请注意，你需要将'YOUR_GOOGLE_MAPS_API_KEY'替换为你自己的Google Maps API Key。你可以在Google Cloud Platform上创建一个项目并启用Geocoding API来获取这个Key。

希望这个示例对你有帮助！