开发喵星球

MQTT是一种轻量级的消息传输协议（Message Queuing Telemetry Transport），旨在实现设备之间的低带宽和高延迟的通信。它是基于发布/订阅模式（Publish/Subscribe）的消息协议，最初由IBM开发，现在成为了一种开放的标准，被广泛应用于物联网（IoT）领域。

MQTT的特点包括：

1. 轻量级：MQTT协议设计简单，消息头部轻量，适用于受限环境的设备，如传感器、嵌入式设备等。
2. 简单易用：MQTT采用发布/订阅模式，消息的发送者（发布者）和接收者（订阅者）之间解耦，通信过程简单易理解。
3. 低带宽、高延迟：MQTT协议设计考虑了网络带宽受限和延迟较高的情况，能够在不理想的网络环境下保持稳定的消息传输。
4. 可靠性：MQTT支持消息的持久化和确认机制，确保消息的可靠传输，同时提供了QoS（Quality of Service）等级，可以根据实际需求进行灵活配置。
5. 灵活性：MQTT支持多种消息格式和负载类型，可以传输文本、二进制数据等多种类型的消息，同时支持SSL/TLS加密，保障通信安全。
6. 适用于多种场景：由于其轻量级和灵活性，MQTT被广泛应用于物联网、传感器网络、远程监控、消息通知等场景，成为连接设备的重要通信协议之一。

若依前后端分离版集成MQTT步骤如下：
1、下载MQTT X测试工具，进行安装

官网地址：https://www.emqx.com/zh/try?product=emqx-ecp

2、 打开MQTT X，新建连接，输入名称，点击连接

3、在ruoyi-common模块下的pom.xml加入依赖

<!--mqtt依赖-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-integration</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-stream</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-mqtt</artifactId>
</dependency>

4、在application.yml添加相关配置，加在Spring配置下

# mqtt
  mqtt:
    username: admin # 用户名
    password: admin # 密码
    hostUrl: tcp://broker.emqx.io:1883 # tcp://ip:端口
    clientId: clientId # 客户端id
    defaultTopic: topic,topic1 # 订阅主题
    timeout: 100 # 超时时间 （单位：秒）
    keepalive: 60 # 心跳 （单位：秒）
    enabled: true # 是否使用mqtt功能

5、在ruoyi-common\src\main\java\com\ruoyi\common\utils目录下新建mqtt文件夹，添加以下三个文件

MqttConfig.java

package com.ruoyi.common.utils.mqtt;

import com.ruoyi.common.utils.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties("spring.mqtt")
public class MqttConfig {
    @Autowired
    private MqttPushClient mqttPushClient;

    /**
     * 用户名
     */
    private String username;
    /**
     * 密码
     */
    private String password;
    /**
     * 连接地址
     */
    private String hostUrl;
    /**
     * 客户Id
     */
    private String clientId;
    /**
     * 默认连接话题
     */
    private String defaultTopic;
    /**
     * 超时时间
     */
    private int timeout;
    /**
     * 保持连接数
     */
    private int keepalive;
    /**
     * mqtt功能使能
     */
    private boolean enabled;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getHostUrl() {
        return hostUrl;
    }

    public void setHostUrl(String hostUrl) {
        this.hostUrl = hostUrl;
    }

    public String getClientId() {
        return clientId;
    }

    public void setClientId(String clientId) {
        this.clientId = clientId;
    }

    public String getDefaultTopic() {
        return defaultTopic;
    }

    public void setDefaultTopic(String defaultTopic) {
        this.defaultTopic = defaultTopic;
    }

    public int getTimeout() {
        return timeout;
    }

    public void setTimeout(int timeout) {
        this.timeout = timeout;
    }

    public int getKeepalive() {
        return keepalive;
    }

    public void setKeepalive(int keepalive) {
        this.keepalive = keepalive;
    }

    public boolean isEnabled() {
        return enabled;
    }

    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }

    @Bean
    public MqttPushClient getMqttPushClient() {
        if(enabled == true){
            String mqtt_topic[] = StringUtils.split(defaultTopic, ",");
            mqttPushClient.connect(hostUrl, clientId, username, password, timeout, keepalive);//连接
            for(int i=0; i<mqtt_topic.length; i++){
                mqttPushClient.subscribe(mqtt_topic[i], 0);//订阅主题
            }
        }
        return mqttPushClient;
    }
}

MqttPushClient.java

package com.ruoyi.common.utils.mqtt;

import com.ruoyi.common.core.domain.AjaxResult;
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import static com.ruoyi.common.core.domain.AjaxResult.error;
import static com.ruoyi.common.core.domain.AjaxResult.success;

@Component
public class MqttPushClient {
    private static final Logger logger = LoggerFactory.getLogger(MqttPushClient.class);

    @Autowired
    private PushCallback pushCallback;

    private static MqttClient client;

    private static MqttClient getClient() {
        return client;
    }

    private static void setClient(MqttClient client) {
        MqttPushClient.client = client;
    }

    /**
     * 客户端连接
     *
     * @param host      ip+端口
     * @param clientID  客户端Id
     * @param username  用户名
     * @param password  密码
     * @param timeout   超时时间
     * @param keepalive 保留数
     */
    public void connect(String host, String clientID, String username, String password, int timeout, int keepalive) {
        MqttClient client;
        try {
            client = new MqttClient(host, clientID, new MemoryPersistence());
            MqttConnectOptions options = new MqttConnectOptions();
            options.setCleanSession(true);
            options.setUserName(username);
            options.setPassword(password.toCharArray());
            options.setConnectionTimeout(timeout);
            options.setKeepAliveInterval(keepalive);
            MqttPushClient.setClient(client);
            try {
                client.setCallback(pushCallback);
                client.connect(options);
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 发布
     *
     * @param qos         连接方式
     * @param retained    是否保留
     * @param topic       主题
     * @param pushMessage 消息体
     */
    public AjaxResult publish(int qos, boolean retained, String topic, String pushMessage) {
        MqttMessage message = new MqttMessage();
        message.setQos(qos);
        message.setRetained(retained);
        message.setPayload(pushMessage.getBytes());
        MqttTopic mTopic = MqttPushClient.getClient().getTopic(topic);
        if (null == mTopic) {
            logger.error("topic not exist");
        }
        MqttDeliveryToken token;
        try {
            token = mTopic.publish(message);
            token.waitForCompletion();
            return success();
        } catch (MqttPersistenceException e) {
            e.printStackTrace();
            return error();
        } catch (MqttException e) {
            e.printStackTrace();
            return error();
        }
    }

    /**
     * 订阅某个主题
     *
     * @param topic 主题
     * @param qos   连接方式
     */
    public void subscribe(String topic, int qos) {
        logger.info("开始订阅主题" + topic);
        try {
            MqttPushClient.getClient().subscribe(topic, qos);
        } catch (MqttException e) {
            e.printStackTrace();
        }
    }

}

PushCallback.java

package com.ruoyi.common.utils.mqtt;

import com.alibaba.fastjson2.JSONObject;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class PushCallback implements MqttCallback {
    private static final Logger logger = LoggerFactory.getLogger(MqttPushClient.class);

    @Autowired
    private MqttConfig mqttConfig;

    private static MqttClient client;

    private static String _topic;
    private static String _qos;
    private static String _msg;

    @Override
    public void connectionLost(Throwable throwable) {
        // 连接丢失后，一般在这里面进行重连
        logger.info("连接断开，可以做重连");
        if (client == null || !client.isConnected()) {
            mqttConfig.getMqttPushClient();
        }
    }

    @Override
    public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
        // subscribe后得到的消息会执行到这里面
        logger.info("接收消息主题 : " + topic);
        logger.info("接收消息Qos : " + mqttMessage.getQos());
        logger.info("接收消息内容 : " + new String(mqttMessage.getPayload()));

        _topic = topic;
        _qos = mqttMessage.getQos()+"";
        _msg = new String(mqttMessage.getPayload());
    }

    @Override
    public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
        logger.info("deliveryComplete---------" + iMqttDeliveryToken.isComplete());
    }

    //别的Controller层会调用这个方法来  获取  接收到的硬件数据
    public String receive() {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("topic", _topic);
        jsonObject.put("qos", _qos);
        jsonObject.put("msg", _msg);
        return jsonObject.toString();
    }

}

注：项目报红的地方可以按Alt+Enter键导依赖

6、运行若依项目，后端可以接收MQTTX发来的数据。