路径选择器-在文件系统中选择目标路径/位置

Question

我需要在Flutter中导出.txt文件。有没有一种对话框可以让用户选择保存文件的路径/位置？ image_picker之类的东西，仅用于路径。

Answer 1

您可以在下面复制粘贴运行完整代码
您可以同时使用https://pub.dev/packages/folder_picker和
https://pub.dev/packages/path_provider_ex
不要忘记添加权限

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

工作演示

完整代码

import 'dart:io';
import 'package:path_provider/path_provider.dart';
import 'package:permission/permission.dart';
import 'package:folder_picker/folder_picker.dart';
import 'package:flutter/material.dart';
import 'package:path_provider_ex/path_provider_ex.dart';
import 'dart:async';
import 'package:flutter/services.dart';

class _FolderPickerDemoState extends State<FolderPickerDemo> {
  Directory externalDirectory;
  Directory pickedDirectory;
  List<StorageInfo> _storageInfo = [];

  Future<void> getPermissions() async {
    final permissions =
    await Permission.getPermissionsStatus([PermissionName.Storage]);
    var request = true;
    switch (permissions[0].permissionStatus) {
      case PermissionStatus.allow:
        request = false;
        break;
      case PermissionStatus.always:
        request = false;
        break;
      default:
    }
    if (request) {
      await Permission.requestPermissions([PermissionName.Storage]);
    }
  }

  Future<void> getStorage() async {
    final directory = await getExternalStorageDirectory();
    print(" ${directory.path}");
    setState(() => externalDirectory = directory);
  }

  Future<void> init() async {
    await getPermissions();
    await getStorage();
  }

  Future<void> initPlatformState() async {
    List<StorageInfo> storageInfo;
    // Platform messages may fail, so we use a try/catch PlatformException.
    try {
      storageInfo = await PathProviderEx.getStorageInfo();
    } on PlatformException {}

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      _storageInfo = storageInfo;
    });
  }

  @override
  void initState() {
    super.initState();
    init();
    initPlatformState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Center(
            child: (_storageInfo.length > 0)
                ? Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  RaisedButton(
                    child:
                    const Text("Pick a folder", textScaleFactor: 1.3),
                    onPressed: () => Navigator.of(context)
                        .push<FolderPickerPage>(MaterialPageRoute(
                        builder: (BuildContext context) {
                          return FolderPickerPage(
                              rootDirectory: Directory(_storageInfo[0].rootDir),
                              action: (BuildContext context,
                                  Directory folder) async {
                                print("Picked directory $folder");
                                setState(() => pickedDirectory = folder);
                                Navigator.of(context).pop();
                              });
                        })),
                  ),
                  (pickedDirectory != null)
                      ? Padding(
                    padding: const EdgeInsets.only(top: 30.0),
                    child: Text("${pickedDirectory.path}"),
                  )
                      : const Text('')
                ])
                : const CircularProgressIndicator()));
  }
}

class FolderPickerDemo extends StatefulWidget {
  @override
  _FolderPickerDemoState createState() => _FolderPickerDemoState();
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Folder picker Demo',
      home: FolderPickerDemo(),
      theme: ThemeData.dark(),
    );
  }
}

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