如何在Flutter Firebase中使用空间进行搜索

dependencies:
  flutter:
    sdk: flutter
  firebase_core: ^1.0.0
  cloud_firestore: ^2.2.0
  geoflutterfire: ^2.0.2

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

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

import 'package:cloud_firestore/cloud_firestore.dart';

final FirebaseFirestore firestore = FirebaseFirestore.instance;

// 添加地理位置字段，并为该字段添加地理空间索引
firestore.collection('locations').add({
  'name': 'Location 1',
  'location': GeoPoint(latitude, longitude),
});

// 更新文档时，可以使用`set`方法
firestore.collection('locations').doc('locationId').set({
  'name': 'Location 2',
  'location': GeoPoint(latitude, longitude),
});

import 'package:geoflutterfire/geoflutterfire.dart';

final GeoFlutterFire geoFlutterFire = GeoFlutterFire();

// 创建GeoFirePoint对象
GeoFirePoint center = geoFlutterFire.point(latitude: centerLat, longitude: centerLng);

// 定义搜索半径（单位：米）
double radius = 1000;

// 执行搜索
Stream<List<DocumentSnapshot>> stream = geoFlutterFire
    .collection(collectionRef: firestore.collection('locations'))
    .within(center: center, radius: radius, field: 'location');

// 使用StreamBuilder监听搜索结果
StreamBuilder<List<DocumentSnapshot>>(
  stream: stream,
  builder: (context, snapshot) {
    if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}');
    }

    if (snapshot.connectionState == ConnectionState.waiting) {
      return CircularProgressIndicator();
    }

    // 处理搜索结果
    List<DocumentSnapshot> documents = snapshot.data!;
    return ListView.builder(
      itemCount: documents.length,
      itemBuilder: (context, index) {
        DocumentSnapshot document = documents[index];
        Map<String, dynamic> data = document.data() as Map<String, dynamic>;
        return ListTile(
          title: Text(data['name']),
          subtitle: Text(data['location'].latitude.toString() + ', ' + data['location'].longitude.toString()),
        );
      },
    );
  },
);