在dart中发出http请求，其中dart:io

import 'dart:io';

void main() async {
  var httpClient = HttpClient();
  var request = await httpClient.getUrl(Uri.parse('https://example.com'));
  var response = await request.close();

  var responseBody = await response.transform(utf8.decoder).join();
  print(responseBody);

  httpClient.close();
}

import 'dart:io';

void main() async {
  var httpClient = HttpClient();
  var request = await httpClient.postUrl(Uri.parse('https://example.com'));
  request.headers.contentType = ContentType.json;
  request.write('{"name": "John", "age": 30}');

  var response = await request.close();

  var responseBody = await response.transform(utf8.decoder).join();
  print(responseBody);

  httpClient.close();
}