flutter从url下载图像

import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

class ImageDownloader extends StatefulWidget {
  final String imageUrl;

  ImageDownloader({required this.imageUrl});

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

class _ImageDownloaderState extends State<ImageDownloader> {
  late Future<File> _imageFile;

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

  Future<File> _downloadImage() async {
    try {
      final response = await http.get(Uri.parse(widget.imageUrl));
      if (response.statusCode == 200) {
        final bytes = await response.bodyBytes;
        final file = File('${(await getApplicationDocumentsDirectory()).path}/image.jpg');
        await file.writeAsBytes(bytes);
        setState(() {
          _imageFile = file;
        });
      }
    } catch (e) {
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Image Downloader'),
      ),
      body: Center(
        child: _imageFile == null
            ? CircularProgressIndicator()
            : Image.file(_imageFile!),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: ImageDownloader(imageUrl: 'https://example.com/image.jpg'),
  ));
}