Flutter 外部ファイルを使いたい - ぶやかー

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外部のファイルを読み込みたい

file_pickerを使うhttps://pub.dev/packages/file_picker

install

pubspec.yamlに追記

dependencies:
  file_picker: ^4.5.1
  flutter:
    sdk: flutter

pub getする

flutter pub get

main.dartなど、file_pikcerを使うファイルでimportする

import 'package:flutter/material.dart';
import 'package:file_picker/file_picker.dart';

...

使い方

ファイルパスやメタ情報の取得

ファイルパスやメタ情報のみ必要な場合

import 'package:flutter/material.dart';
import 'package:file_picker/file_picker.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData.dark(),
      home: const MyHomePage(title: 'Flutter Rank Beginner'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Column(
        children: [
          Text('top'),
          Row(
            children: [
              Flexible(
                child: TextField(),
              ),
              ElevatedButton(
                child: Text('Button'),
                onPressed: () async {
                  FilePickerResult? result =
                      await FilePicker.platform.pickFiles();

                  if (result != null) {
                    PlatformFile file = result.files.single;
                    print(file.path);
                  } else {
                    print('User Canceled');
                  }
                },
              ),
            ],
          ),
          Text('bottom'),
        ],
      ),
    );
  }
}

選択したテキストファイルの読み込み

ioを使う。

import 'package:flutter/material.dart';
import 'package:file_picker/file_picker.dart';
import 'dart:io';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData.dark(),
      home: const MyHomePage(title: 'Flutter Rank Beginner'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Column(
        children: [
          Text('top'),
          Row(
            children: [
              Flexible(
                child: TextField(),
              ),
              ElevatedButton(
                child: Text('Button'),
                onPressed: () async {
                  FilePickerResult? result =
                      await FilePicker.platform.pickFiles();

                  if (result != null) {
                    File file = File(result.files.first.path!);

                    String filePath = file.path;
                    print(filePath);

                    // ファイル全体を文字列として読み込む
                    String fileData = await file.readAsString();
                    print(fileData);

                    // ファイルを1ずつリストとして読み込む
                    List fileDatas = await file.readAsLines();
                    fileDatas.forEach((element) {
                      print(element.toString());
                    });
                  } else {
                    print('User Canceled');
                  }
                },
              ),
            ],
          ),
          Text('bottom'),
        ],
      ),
    );
  }
}

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