mqtt.dart

import 'dart:io';

import 'package:mqtt_client/mqtt_client.dart';
import 'package:mqtt_client/mqtt_server_client.dart';

Future<void> main(List<String> arguments) async {
  final client = MqttServerClient('mosquitto.local', '');
  client.setProtocolV311();
  client.keepAlivePeriod = 30;
  await client.connect();
  
  // subscribe to all topics
  client.subscribe('#', MqttQos.atMostOnce);

  await for (final batch in client.updates!) {
    for (final message in batch) {
      final p = message.payload;
      if (p is! MqttPublishMessage) continue;
      final pt = MqttPublishPayload.bytesToStringAsString(p.payload.message);
      print('<${message.topic}>: $pt');
    }
  }
}

pubspec.yaml

name: pid
description: MQTT example
version: 1.0.0

environment:
  sdk: '>=2.18.4 <3.0.0'

dependencies:
  mqtt_client: ^9.7.2