flutter:用http库下载文件

一，安装第三方库

地址:

https://pub.dev/packages/http

编辑pubspec.yaml：

dependencies:
  flutter:
    sdk: flutter
  path_provider: ^2.1.5
  http: ^1.3.0

然后点击 pub get

二，代码:

import 'package:flutter/material.dart';
import 'package:http/http.dart' show get;
import 'package:path_provider/path_provider.dart';
import 'dart:io';

class DownloadPage extends StatefulWidget {
  final Map arguments;

  // 为title设置一个默认参数，这样的跳转该界面时可以不传值。
  DownloadPage({super.key, required this.arguments});
  @override
  State<DownloadPage> createState() => _DownloadPageState();
}

class _DownloadPageState extends State<DownloadPage> {


  _downloadFile(String url) async {
    //comment out the next two lines to prevent the device from getting
    // the image from the web in order to prove that the picture is
    // coming from the device instead of the web.
    //var url = "https://www.tottus.cl/static/img/productos/20104355_2.jpg"; // <-- 1

    var response = await get(Uri.parse(url)); // <--2
    var documentDirectory = await getApplicationDocumentsDirectory();
    var firstPath = documentDirectory.path + "/images";
    var filePathAndName = documentDirectory.path + '/images/pic.jpg';
    //comment out the next three lines to prevent the image from being saved
    //to the device to show that it's coming from the internet
    await Directory(firstPath).create(recursive: true); // <-- 1
    File file2 = new File(filePathAndName);             // <-- 2
    file2.writeAsBytesSync(response.bodyBytes);         // <-- 3
    return filePathAndName;
  }

  void _setImageData(filePathAndName) {
    setState(() {
      imageData = filePathAndName;
      dataLoaded = true;
    });
  }

  String imageData = '';
  bool dataLoaded = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.primaryContainer,
        title: Text(widget.arguments["title"]),
      ),

      body: Center(
        child:Column(
            children: [
            ElevatedButton(
            onPressed: () async {

      var url="https://wx3.sinaimg.cn/mw2000/7546503fly1hzsxkui8hoj21400u0n2h.jpg";
      _downloadFile(url).then((value) {
        print("下载图片完整路径:");
        print(value);
        _setImageData(value);
      });



      },
            child:  Row(
                mainAxisSize: MainAxisSize.min, // 根据内容调整大小
                children: <Widget>[
                  Icon(Icons.add), // 图标在左侧
                  SizedBox(width: 10), // 可选：添加一些间隔
                  Text("选择文件"), // 文本在右侧
                ],
              ),
            ),
              Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Image.file(File(imageData), width: 600.0, height: 290.0)
                ],
              ),
            ],
          ),

        ),
      );
  }
}

 

三，测试效果: