Uploader.dart

Purpose

Uploader.dart manages periodic uploads of sensor data files (.gz) to a remote server. It supports configurable upload URLs, runs background uploads on a timer, and manages device storage access across platforms.

Key Imports

import 'dart:async';
import 'dart:io';
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:path/path.dart';
import 'package:flutter/services.dart' show rootBundle;
import 'package:path_provider/path_provider.dart';
import 'package:http_parser/http_parser.dart';
import 'package:shared_preferences/shared_preferences.dart';

Used for:

  • Asynchronous execution and timers

  • File I/O

  • HTTP file uploads

  • Local file system path access

  • Configuration and preferences

Configuration

static Future<void> loadConfig() async {
  final config = await rootBundle.loadString('assets/config.txt');
  serverUrl = config.trim();
}

  • Loads the server URL from a local asset file (assets/config.txt).

  • Allows dynamic changes to upload endpoints without recompiling the app.

Upload Scheduler

static void startMonitoringAndUploading() {
  Timer.periodic(uploadInterval, (Timer t) => startUploading());
}

  • Starts periodic upload every 60 seconds (uploadInterval).

  • Calls startUploading() automatically on schedule.

File Upload Function

static Future<void> startUploading() async

  • Gets the external storage directory (platform-aware).

  • Filters .gz files.

  • Uploads each using uploadFile() method.

Example upload logic:

var request = http.MultipartRequest('POST', Uri.parse(serverUrl));
request.files.add(await http.MultipartFile.fromPath('file', file.path));
await request.send();

Upload State

static DateTime? lastUploadTimestamp;

  • Records the last successful upload time.

  • Could be used for failure tracking or UI status indicators.

Preferences

Preferences could be used for:

  • Upload logs

  • Retry counts

  • User ID or app version tracking

Integration

Used in:

  • BackgroundHandling.dart: Invokes Uploader.startUploading() periodically.

  • StatusChecker.dart: Can verify file counts or trigger uploads if needed.

Platform Considerations

  • Uses getExternalStorageDirectory() for Android.

  • Handles differences for iOS using platform checks.