Flutter MQTT连接并使用

再开过程中我们经常使用到MQTT 进行 订阅，来进行 消息的发送、接受等操作。

下面就是我对Flutter MQTT 的简单实用并，这里为方便大家使用 ,我封装了一个MQTT管理类，代码如下，功能介绍也写在 代码注释中。

注意：Flutter 开发环境为 2.8.0,如果版本 存在差别，要略微 修改。

插件：

mqtt_client: ^9.6.8

import 'dart:async';
import 'package:amazingbox/util/LoggerUtil.dart';//日志打印类，可忽略
import 'package:mqtt_client/mqtt_client.dart'; // Mqtt插件
import 'package:mqtt_client/mqtt_server_client.dart'; // Mqtt插件
import 'package:typed_data/typed_buffers.dart';

typedef ConnectedCallback = void Function();

class MqttUtil {
  MqttQos qos = MqttQos.atLeastOnce;
  late MqttServerClient mqttClient;
  static MqttUtil? _instance;

  static MqttUtil? getInstance() {
    _instance ??= MqttUtil();
    return _instance;
  }

  /*
  * 链接服务器
  * */
  Future connect(String server, int port,
      String clientIdentifier, String username, String password,
      {bool isSsl = false}) {
    mqttClient = MqttServerClient.withPort(server, clientIdentifier, port);
    mqttClient.onConnected = onConnected;
    mqttClient.onSubscribed = _onSubscribed;
    mqttClient.onSubscribeFail = _onSubscribeFail;
    mqttClient.onUnsubscribed = _onUnSubscribed;
    mqttClient.pongCallback = pong; //收到 PING 响应回调
    mqttClient.setProtocolV311();
    mqttClient.logging(on: false);
    if (isSsl) {
      mqttClient.secure = true;
      mqttClient.onBadCertificate = (dynamic a) => true;
    }
    _log("_正在连接中...");
    return mqttClient.connect(username, password);
  }

  /*
  * 发送数据
  * */
  int publishMessage(String pTopic, String msg) {
    _log("_发送数据-topic:$pTopic,playLoad:$msg");
    Uint8Buffer uint8buffer = Uint8Buffer();
    var codeUnits = msg.codeUnits;
    uint8buffer.addAll(codeUnits);
    return mqttClient.publishMessage(pTopic, qos, uint8buffer, retain: false);
  }

  /*
  *发送数据
  * */
  int publishRawMessage(String pTopic, List list) {
    _log("_发送数据-topic:$pTopic,playLoad:$list");
    Uint8Buffer uint8buffer = Uint8Buffer();
    //    var codeUnits = msg.codeUnits;
    uint8buffer.addAll(list);
    return mqttClient.publishMessage(pTopic, qos, uint8buffer, retain: false);
  }

  // TODO: 订阅主题
  Subscription? subscribeMessage(String subtopic) {
    return mqttClient.subscribe(subtopic, qos);
  }

  // TODO: 取消订阅
  void unsubscribeMessage(String? unSubtopic) {
    mqttClient.unsubscribe(unSubtopic!);
  }

  // TODO: MQTT状态获取
  MqttClientConnectionStatus? getMqttStatus() {
    return mqttClient.connectionStatus;
  }

  // TODO: 监听MQTT接到的消息
  Stream>>? updates() {
    _log("_监听成功!");
    return mqttClient.updates;
  }

  // TODO: 链接成功
  onConnected() {
    //    mqttClient.onConnected = callback;
    _log("链接成功");
  }

  // TODO: 断开链接
  disconnect() {
    mqttClient.disconnect();
    _log("断开链接");
  }

  // TODO: 连接断开回调
  onDisConnected(ConnectedCallback callback) {
    mqttClient.onDisconnected = callback;
  }

  // TODO: _订阅主题成功
  _onSubscribed(String topic) {
    _log("_订阅主题成功---topic:$topic");
  }

  // TODO: _取消订阅主题成功
  _onUnSubscribed(String? topic) {
    _log("_取消订阅主题成功---topic:$topic");
  }

  // TODO: 订阅失败
  _onSubscribeFail(String topic) {
    _log("_onSubscribeFail");
  }

  // TODO: 收到 PING 响应
  void pong() {
    print('收到 PING 响应');
  }

  _log(String msg) {
    LogD("MQTT-->$msg");
  }
}

以上就是MQTT工具类的封装，每个方法都有对应的注释，具体都什么作用就不做过多介绍，下面着重介绍一下使用。代码如下：

连接

//连接
MqttUtil.getInstance()?.connect("链接地址", "端口号", "设备唯一标识", "账号", "密码");

订阅

MqttUtil.getInstance()?.subscribeMessage("订阅topic");

消息监听

    MqttUtil.getInstance()?.updates()!.listen((List> mqttMessageList) {
      print('----------------------mqqt 消息监听------------------------');
      print(mqttMessageList);
      // final MqttPublishMessage message = mqttMessageList[0].payload;
      // final payload = MqttPublishPayload.bytesToStringAsString(message.payload.message);
      // print('消息:$payload,主题: <${mqttMessageList[0].topic}>');
    });

取消连接

    MqttUtil.getInstance()?.disconnect();

取消订阅

MqttUtil.getInstance()?.unsubscribeMessage("取消订阅的Topic");

发动消息

    MqttUtil.getInstance()?.publishMessage("要发送的topic", "消息内容");

// 发送的消息内容为列表
MqttUtil.getInstance()?.publishRawMessage("发送的topic", []);

获取MQTT状态

MqttUtil.getInstance()?.getMqttStatus();

到此就完成了MQTT封装和使用，希望对大家有所帮助