如何從“file_picker”flutter web 中獲取文件 stream 的值？

Question

我需要從圖庫中選擇一張圖片，還有一個用於拖動圖片的字段。 對於拖放字段，我使用了 flutter_dropzone 。 並使用getFileStream(event)數據將數據上傳到file_picker: ^5.2.4用於從圖庫中選擇圖像。那么如何從這個 package 獲取文件流數據。我得到了字節，但這不起作用我需要文件流值

使用 file_picker 的代碼

void chooseImage() async {
    pickedFile = await FilePicker.platform.pickFiles(
        type: FileType.custom,
      withReadStream: true,
      allowedExtensions: [
        'jpg','jpeg','png'
      ]
    );
    if (pickedFile != null) {
      try {
        base64   = pickedFile!.files.first.bytes;
        base64String.value=base64.toString();
        String mime = pickedFile!.files.first.extension.toString();
        getS3url("image/$mime" ,base64String.value,from: "cameraIcon");
//withReadStream
      //getFileStream(event);
      } catch (err) {
        print(err);
      }
    } else {

    }
  }

Answer 1

復制自https://github.com/miguelpruivo/flutter_file_picker/wiki/FAQ

import 'package:file_picker/file_picker.dart';
import 'package:http/http.dart' as http;
import 'package:http_parser/http_parser.dart';
import 'package:mime/mime.dart';

void main() async {
  final result = await FilePicker.platform.pickFiles(
    type: FileType.custom,
    allowedExtensions: [
      'jpg',
      'png',
      'mp4',
      'webm',
    ],
    withData: false,
    withReadStream: true,
  );

  if (result == null || result.files.isEmpty) {
    throw Exception('No files picked or file picker was canceled');
  }

  final file = result.files.first;
  final filePath = file.path;
  final mimeType = filePath != null ? lookupMimeType(filePath) : null;
  final contentType = mimeType != null ? MediaType.parse(mimeType) : null;

  final fileReadStream = file.readStream;
  if (fileReadStream == null) {
    throw Exception('Cannot read file from null stream');
  }
  final stream = http.ByteStream(fileReadStream);

  final uri = Uri.https('siasky.net', '/skynet/skyfile');
  final request = http.MultipartRequest('POST', uri);
  final multipartFile = http.MultipartFile(
    'file',
    stream,
    file.size,
    filename: file.name,
    contentType: contentType,
  );
  request.files.add(multipartFile);

  final httpClient = http.Client();
  final response = await httpClient.send(request);

  if (response.statusCode != 200) {
    throw Exception('HTTP ${response.statusCode}');
  }

  final body = await response.stream.transform(utf8.decoder).join();

  print(body);
}