Flutter：在热重载之前无法加载资产和 path_provider

Question

I'm downloading an picture from the internet and saving it in the platform's directory.
I get the platform's directory from path_provider and (await getApplicationDocumentsDirectory()).path .
On iOS it works very well but on android I always get Unable to load asset: <path_to_my_directory> .

EDIT: I get this error on first start, after a hot restart, it works very well...

Here's a code sample to test:

import 'package:dio/dio.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  bool dataLoaded = false;
  String pathToSave;

  @override
  void initState() {
    downloadImage();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: dataLoaded ? getImageBody() : CircularProgressIndicator()
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }

  getImageBody() {
    return Image.asset(pathToSave);
  }

  void downloadImage() async {
    String url = 'https://github.githubassets.com/images/modules/open_graph/github-mark.png';
    pathToSave = '${(await getApplicationDocumentsDirectory()).path}/github-mark.png';
    await Dio().download(url, pathToSave);
    print(pathToSave);
    setState(() {
      dataLoaded = true;
    });
  }
}

dependencies:

path_provider: ^1.6.11
dio: ^3.0.9

Answer 1

For all, who run in similar issues:

• Image.asset(path) loads an asset, thats in the path BEFORE app start.
• Image.file(path) loads an asset/file and only needs an reference to an file eg File(path). That means, that assets can be dynamically added or static added before app start.