如何使用 Flutter 下载文件并将其存储在 Downloads 文件夹中 [英] How to download a file and store it in Downloads folder using Flutter

问题描述

我正在使用 Flutter 1.10.3 构建应用程序，但无法将图像下载到设备的下载文件夹.

I'm building an App using Flutter 1.10.3 and I'm having difficulties downloading images to the Downloads folder of the device.

是否可以在不使用任何第三部分库的情况下这样做?

Is there an option to do so without using any 3rd-part libraries?

推荐答案

添加一些必需的依赖项，我只有一个 android 的测试演示.在 IOS 设备中实现时，请查看 file_utils 和 path_provider.

Add few required dependencies, I have a test demo with android only. please review file_utils and path_provider while you implement in IOS device.

  dio: ^3.0.0

  path_provider: ^1.3.0

  simple_permissions: ^0.1.9

  file_utils: ^0.1.3

注意: simple_permissions 断开连接请使用这个依赖permission_handler

Note: simple_permissions is disconnected please use this dependency permission_handler

您需要为 android manifest 文件添加权限.

You are required to add permissions on the android manifest file.

  <uses-permission android:name="android.permission.INTERNET"/>
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

示例代码:

  import 'dart:io';
  import 'package:flutter/material.dart';
  import 'package:dio/dio.dart';
  import 'package:path_provider/path_provider.dart';
  import 'dart:async';
  import 'package:simple_permissions/simple_permissions.dart';
  import 'package:file_utils/file_utils.dart';
  import 'dart:math';

  void main() => runApp(Downloader());

  class Downloader extends StatelessWidget {
    @override
    Widget build(BuildContext context) => MaterialApp(
          title: "File Downloader",
          debugShowCheckedModeBanner: false,
          home: FileDownloader(),
          theme: ThemeData(primarySwatch: Colors.blue),
        );
  }

  class FileDownloader extends StatefulWidget {
    @override
    _FileDownloaderState createState() => _FileDownloaderState();
  }

  class _FileDownloaderState extends State<FileDownloader> {

    final imgUrl = "https://images6.alphacoders.com/683/thumb-1920-683023.jpg";
    bool downloading = false;
    var progress = "";
    var path = "No Data";
    var platformVersion = "Unknown";
    Permission permission1 = Permission.WriteExternalStorage;
    var _onPressed;
    static final Random random = Random();
    Directory externalDir;

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


    Future<void> downloadFile() async {
      Dio dio = Dio();
      bool checkPermission1 =
          await SimplePermissions.checkPermission(permission1);
      // print(checkPermission1);
      if (checkPermission1 == false) {
        await SimplePermissions.requestPermission(permission1);
        checkPermission1 = await SimplePermissions.checkPermission(permission1);
      }
      if (checkPermission1 == true) {
        String dirloc = "";
        if (Platform.isAndroid) {
          dirloc = "/sdcard/download/";
        } else {
          dirloc = (await getApplicationDocumentsDirectory()).path;
        }

        var randid = random.nextInt(10000);

        try {
          FileUtils.mkdir([dirloc]);
          await dio.download(imgUrl, dirloc + randid.toString() + ".jpg",
              onReceiveProgress: (receivedBytes, totalBytes) {
            setState(() {
              downloading = true;
              progress =
                  ((receivedBytes / totalBytes) * 100).toStringAsFixed(0) + "%";
            });
          });
        } catch (e) {
          print(e);
        }

        setState(() {
          downloading = false;
          progress = "Download Completed.";
          path = dirloc + randid.toString() + ".jpg";
        });
      } else {
        setState(() {
          progress = "Permission Denied!";
          _onPressed = () {
            downloadFile();
          };
        });
      }
    }

    @override
    Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          title: Text('File Downloader'),
        ),
        body: Center(
            child: downloading
                ? Container(
                    height: 120.0,
                    width: 200.0,
                    child: Card(
                      color: Colors.black,
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          CircularProgressIndicator(),
                          SizedBox(
                            height: 10.0,
                          ),
                          Text(
                            'Downloading File: $progress',
                            style: TextStyle(color: Colors.white),
                          ),
                        ],
                      ),
                    ),
                  )
                : Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Text(path),
                      MaterialButton(
                        child: Text('Request Permission Again.'),
                        onPressed: _onPressed,
                        disabledColor: Colors.blueGrey,
                        color: Colors.pink,
                        textColor: Colors.white,
                        height: 40.0,
                        minWidth: 100.0,
                      ),
                    ],
                  )));
  }

这篇关于如何使用 Flutter 下载文件并将其存储在 Downloads 文件夹中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！