如何通过Dart/Flutter中的“application/octet-stream”将png文件发送到Microsoft Custom Vision？

import 'package:http/http.dart' as http;

Future<void> sendPngToCustomVision(String filePath, String apiKey) async {
  // 读取PNG文件的内容
  List<int> pngBytes = await File(filePath).readAsBytes();

  // 构建HTTP请求
  var request = http.MultipartRequest(
    'POST',
    Uri.parse('https://customvision.ai/api/<YOUR_PROJECT_ID>/image'),
  );

  // 设置请求头，包括API密钥和内容类型
  request.headers['Prediction-Key'] = apiKey;
  request.headers['Content-Type'] = 'application/octet-stream';

  // 添加PNG文件的内容到请求体中
  request.files.add(
    http.MultipartFile.fromBytes(
      'image',
      pngBytes,
      filename: 'image.png',
    ),
  );

  // 发送请求并获取响应
  var response = await request.send();

  // 处理响应
  if (response.statusCode == 200) {
    // 请求成功
    print('PNG文件发送成功！');
  } else {
    // 请求失败
    print('PNG文件发送失败：${response.statusCode}');
  }
}

String pngFilePath = '/path/to/image.png';
String customVisionApiKey = '<YOUR_CUSTOM_VISION_API_KEY>';

sendPngToCustomVision(pngFilePath, customVisionApiKey);