background_downloader 1.0.2

A background file downloader for iOS and Android. Define where to get your file from, where to store it, and how you want to monitor the download, and the background loader will ensure this is done in [...]

example/lib/main.dart

import 'dart:async';

import 'package:background_downloader/background_downloader.dart';
import 'package:flutter/material.dart';
import 'package:logging/logging.dart';
import 'package:provider/provider.dart';

import 'widgets.dart';

void main() {
  Logger.root.onRecord.listen((LogRecord rec) {
    print('${rec.loggerName}>${rec.level.name}: ${rec.time}: ${rec.message}');
  });

  runApp(const MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({super.key});

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  final buttonTexts = ['Download', 'Cancel', 'Reset'];

  ButtonState buttonState = ButtonState.download;
  bool downloadWithError = false;
  DownloadTaskStatus downloadTaskStatus = DownloadTaskStatus.undefined;
  BackgroundDownloadTask? backgroundDownloadTask;
  StreamController<DownloadProgressIndicatorUpdate> updateStream =
      StreamController();

  @override
  void initState() {
    super.initState();
    FileDownloader.initialize(
        downloadStatusCallback: myDownloadStatusCallback,
        downloadProgressCallback: myDownloadProgressCallback);
  }

  /// Process the status updates coming from the downloader
  ///
  /// Stores the task status
  void myDownloadStatusCallback(
      BackgroundDownloadTask task, DownloadTaskStatus status) {
    if (task == backgroundDownloadTask) {
      buttonState = status == DownloadTaskStatus.running
          ? ButtonState.cancel
          : ButtonState.reset;
      setState(() {
        downloadTaskStatus = status;
      });
    }
  }

  /// Process the progress updates coming from the downloader
  ///
  /// Adds an update object to the stream that the main UI listens to
  void myDownloadProgressCallback(
      BackgroundDownloadTask task, double progress) {
    updateStream.add(DownloadProgressIndicatorUpdate(task.filename, progress));
  }

  @override
  Widget build(BuildContext context) {
    return StreamProvider<DownloadProgressIndicatorUpdate>.value(
        value: updateStream.stream,
        initialData: DownloadProgressIndicatorUpdate('', 1),
        child: MaterialApp(
          home: Scaffold(
              appBar: AppBar(
                title: const Text('background_downloader example app'),
              ),
              body: Center(
                  child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Padding(
                      padding: const EdgeInsets.all(16),
                      child: Row(
                        children: [
                          Expanded(
                              child: Text('Force error',
                                  style:
                                      Theme.of(context).textTheme.headline6)),
                          Switch(
                              value: downloadWithError,
                              onChanged: (value) {
                                setState(() {
                                  downloadWithError = value;
                                });
                              })
                        ],
                      ),
                    ),
                    Center(
                        child: ElevatedButton(
                      onPressed: processButtonPress,
                      child: Text(
                        buttonTexts[buttonState.index],
                        style: Theme.of(context)
                            .textTheme
                            .headline4
                            ?.copyWith(color: Colors.white),
                      ),
                    )),
                    Padding(
                      padding: const EdgeInsets.all(16.0),
                      child: Row(
                        children: [
                          const Expanded(child: Text('File download status:')),
                          Text('$downloadTaskStatus')
                        ],
                      ),
                    )
                  ],
                ),
              )),
              bottomSheet: const DownloadProgressIndicator()),
        ));
  }

  Future<void> processButtonPress() async {
    switch (buttonState) {
      case ButtonState.download:
        // start download
        backgroundDownloadTask = BackgroundDownloadTask(
            url: downloadWithError
                ? 'https://sitethatdoesnotexist.com'
                : 'https://github.com/yourkin/fileupload-fastapi/raw/a85a697cab2f887780b3278059a0dd52847d80f3/tests/data/test-5mb.bin',
            filename: 'zipfile.zip',
            directory: 'my/directory',
            baseDirectory: BaseDirectory.applicationDocuments,
            progressUpdates:
                DownloadTaskProgressUpdates.statusChangeAndProgressUpdates);
        await FileDownloader.enqueue(backgroundDownloadTask!);
        break;
      case ButtonState.cancel:
        // cancel download
        if (backgroundDownloadTask != null) {
          await FileDownloader.cancelTasksWithIds(
              [backgroundDownloadTask!.taskId]);
        }
        break;
      case ButtonState.reset:
        downloadTaskStatus = DownloadTaskStatus.undefined;
        buttonState = ButtonState.download;
        break;
    }
    if (mounted) {
      setState(() {});
    }
  }
}

enum ButtonState { download, cancel, reset }