Flutter GPS历史记录插件gps_history的使用

GPS History for Dart

模块旨在表示以 >= 1 秒频率记录的GPS点的历史。特性包括：

• 三种类型的GPS点：一种仅包含最基本信息的简洁类型，一种包含更多元数据（如方向、速度等）的类型，这种类型对生成GPX文件非常有用。此外，还有一种表示在某地点停留时间较长的点，这可以用于减少数据库中的重复条目。

• 不同的内存存储系统来存储GPS点：要么简单地基于列表，要么采用高效的二进制表示，每个点大约占用 14 到 22 字节（代价是精度略有损失，但该损失在GPS传感器的精度范围之内）。

• 对Google位置历史JSON导出的极低内存且快速解析器。作为参考，使用Dart JSON库直接解析一个约500MB的历史文件大约需要2GB的内存，在Intel Core i7-8565U处理器上每秒可产生约140k个点，而自定义解析器几乎不增加额外内存开销，并且输出速度比前者快2.5到3.5倍。在移动设备上解析Google位置历史时无需担心内存不足的问题。

• 模块化和可扩展架构：添加自己的点定义、容器或持久性机制。

• 包含大量单元测试、示例、基准测试和文档。

• 时间和距离处理的实用函数。

• 支持空安全。

• 第三方库依赖仅限于浅层功能，并且这些库都是主流且得到良好支持的。

示例

读取Google JSON文件

import 'dart:io';
import 'package:gps_history/gps_history.dart';
import 'package:gps_history/gps_history_convert.dart';

void main() async {
  final filename = 'data/g_history_sample.json';

  final file = File(filename);
  final gpsStays = GpcCompactGpsStay();

  final fileStream = file.openRead();

  final points = fileStream.transform(GoogleJsonHistoryDecoder(
      minSecondsBetweenDatapoints: 1, accuracyThreshold: 500));

  final stays = points.transform(
      PointsToStaysDecoder(maxTimeGapSeconds: 10, maxDistanceGapMeters: 10));

  await for (final s in stays) {
    gpsStays.add(s);
  }

  print('Read ${gpsStays.length} points');

  // 计算点的记录频率
  final intervals = <int>[];
  final durations = <int>[];
  final distances = <double>[];
  GpsStay? prevPoint;

  for (final s in gpsStays) {
    durations.add(s.endTime.difference(s.startTime).inSeconds);
    if (prevPoint != null) {
      final diff = s.time.difference(prevPoint.endTime).inSeconds;
      intervals.add(diff);

      final dist = distance(prevPoint, s);
      distances.add(dist);
    }
    prevPoint = s;
  }

  intervals.sort();
  durations.sort();
  distances.sort();

  if (intervals.isNotEmpty) {
    print('Intervals:');
    print('  min    = ${intervals[0]} s');
    print('  median = ${intervals[intervals.length ~/ 2]} s');
    print('  max    = ${intervals[intervals.length - 1]} s');
  }
  if (durations.isNotEmpty) {
    print('Durations:');
    print('  min    = ${durations[0]} s');
    print('  median = ${durations[durations.length ~/ 2]} s');
    print('  max    = ${durations[durations.length - 1]} s');
  }
  if (distances.isNotEmpty) {
    print('Distances:');
    print('  min    = ${distances[0].toStringAsFixed(2)} m');
    print('  median = ${distances[distances.length ~/ 2].toStringAsFixed(2)} m');
    print('  max    = ${distances[distances.length - 1].toStringAsFixed(2)} m');
  }
}

保存/重新加载数据

import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:gps_history/gps_history.dart';
import 'package:gps_history/gps_history_convert.dart';

void main() async {
  final databasePath = await getApplicationDocumentsDirectory();
  final db = await openDatabase(databasePath.path + '/gps_history.db', version: 1, onCreate: (db, version) async {
    await db.execute('CREATE TABLE gps_stay (id INTEGER PRIMARY KEY, latitude REAL, longitude REAL, startTime TEXT, endTime TEXT)');
  });

  final gpsStays = GpcCompactGpsStay();

  // 假设你已经从某个地方获取到了gpsStays对象
  await db.transaction((txn) async {
    final batch = txn.batch();
    for (var stay in gpsStays) {
      batch.insert('gps_stay', {
        'latitude': stay.latitude,
        'longitude': stay.longitude,
        'startTime': stay.startTime.toIso8601String(),
        'endTime': stay.endTime.toIso8601String()
      });
    }
    await batch.commit(noResult: true);
  });

  print('Data saved successfully.');

  // 重新加载数据
  final loadedStays = GpcCompactGpsStay();
  final loadedStaysList = await db.query('gps_stay');
  for (var stay in loadedStaysList) {
    final gpsStay = GpsStay(
      latitude: stay['latitude'],
      longitude: stay['longitude'],
      startTime: DateTime.parse(stay['startTime']),
      endTime: DateTime.parse(stay['endTime'])
    );
    loadedStays.add(gpsStay);
  }

  print('Data reloaded successfully.');
}

将Google JSON文件转换为SQLite数据库

import 'dart:io';
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';
import 'package:gps_history/gps_history.dart';
import 'package:gps_history/gps_history_convert.dart';

void main() async {
  final databasePath = await getApplicationDocumentsDirectory();
  final db = await openDatabase(databasePath.path + '/gps_history.db', version: 1, onCreate: (db, version) async {
    await db.execute('CREATE TABLE gps_stay (id INTEGER PRIMARY KEY, latitude REAL, longitude REAL, startTime TEXT, endTime TEXT)');
  });

  final filename = 'data/g_history_sample.json';

  final file = File(filename);
  final gpsStays = GpcCompactGpsStay();

  final fileStream = file.openRead();

  final points = fileStream.transform(GoogleJsonHistoryDecoder(
      minSecondsBetweenDatapoints: 1, accuracyThreshold: 500));

  final stays = points.transform(
      PointsToStaysDecoder(maxTimeGapSeconds: 10, maxDistanceGapMeters: 10));

  await for (final s in stays) {
    gpsStays.add(s);
  }

  print('Read ${gpsStays.length} points');

  await db.transaction((txn) async {
    final batch = txn.batch();
    for (var stay in gpsStays) {
      batch.insert('gps_stay', {
        'latitude': stay.latitude,
        'longitude': stay.longitude,
        'startTime': stay.startTime.toIso8601String(),
        'endTime': stay.endTime.toIso8601String()
      });
    }
    await batch.commit(noResult: true);
  });

  print('Data saved successfully.');
}