flutter - 如何在 Flutter 中获取下载路径？

Question

我正在使用以下代码获取下载文件夹的路径:

final output = await getExternalStorageDirectory();
RegExp pathToDownloads = new RegExp(r'.+0\/');
final outputPath = '${pathToDownloads.stringMatch(output.path).toString()}Downloads';

上面的代码生成这个字符串: /storage/emulated/0/Downloads
但是控制台说“没有这样的文件或目录”。我创建了这个路径字符串，因为堆栈溢出的一些答案提到上面是下载文件夹的位置，但它不是。那么在android上下载文件夹的路径是什么以及如何访问它？

Answer 1

您可以在下面复制粘贴运行完整代码
以下示例代码将文本文件写入 Downloads 文件夹

第 1 步:您可以将 WRITE_EXTERNAL_STORAGE 添加到 AndroidManifest.xml

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

第 2 步:使用包 ext_storage https://pub.dev/packages/ext_storage 和 https://pub.dev/packages/permission_handler 4.4.0 请求权限

dependencies:
  flutter:
    sdk: flutter
  ext_storage: any
  permission_handler: 4.4.0 

第 4 步:请求许可

 void requestPermission() {
    PermissionHandler().requestPermissions([PermissionGroup.storage]);
  }

第 5 步:使用 Downloads 获取 ExtStorage.getExternalStoragePublicDirectory 文件夹

String path = await ExtStorage.getExternalStoragePublicDirectory(
        ExtStorage.DIRECTORY_DOWNLOADS);

工作演示



完整代码

import 'package:flutter/material.dart';
import 'package:ext_storage/ext_storage.dart';
import 'dart:io';
import 'package:permission_handler/permission_handler.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> {
  int _counter = 0;

  void _incrementCounter() async {
    String path = await ExtStorage.getExternalStoragePublicDirectory(
        ExtStorage.DIRECTORY_DOWNLOADS);
    print(path);
    File file = await File('$path/counter.txt');
    file.writeAsString('this is test');

    setState(() {
      _counter++;
    });
  }

  void requestPermission() {
    PermissionHandler().requestPermissions([PermissionGroup.storage]);
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}