1）RabbitMQ启用MQTT插件

root@mq:/# rabbitmq-plugins enable rabbitmq_mqtt
Enabling plugins on node rabbit@mq:
rabbitmq_mqtt
The following plugins have been configured:rabbitmq_managementrabbitmq_management_agentrabbitmq_mqttrabbitmq_web_dispatch
Applying plugin configuration to rabbit@mq...
The following plugins have been enabled:rabbitmq_mqttstarted 1 plugins.
root@mq:/# rabbitmq-plugins enable rabbitmq_web_mqtt
Enabling plugins on node rabbit@mq:
rabbitmq_web_mqtt
The following plugins have been configured:rabbitmq_managementrabbitmq_management_agentrabbitmq_mqttrabbitmq_web_dispatchrabbitmq_web_mqtt
Applying plugin configuration to rabbit@mq...
The following plugins have been enabled:rabbitmq_web_mqttstarted 1 plugins.
root@mq:/# 

2）RabbitMQ管理控制台查看
如果插件启动成功，rabbitmq会打开1883和15675端口：

3）用MQTTX工具测试

4）用eclipse paho客户端测试
添加依赖

 <dependency><groupId>org.eclipse.paho</groupId><artifactId>org.eclipse.paho.client.mqttv3</artifactId><version>1.2.5</version>
</dependency>

收发消息测试

@RestController
public class DemoController {@GetMapping("/publish")public String publish() throws MqttException {MqttClientPersistence persistence = new MemoryPersistence();;//内存持久化MqttClient client = new MqttClient("tcp://192.168.137.138:1883", "abc", persistence);//连接选项中定义用户名密码和其它配置MqttConnectOptions options = new MqttConnectOptions();options.setCleanSession(true);//参数为true表示清除缓存，也就是非持久化订阅者，这个时候只要参数设为true，一定是非持久化订阅者。而参数设为false时，表示服务器保留客户端的连接记录options.setAutomaticReconnect(true);//是否自动重连options.setConnectionTimeout(30);//连接超时时间  秒options.setKeepAliveInterval(10);//连接保持检查周期  秒options.setMqttVersion(MqttConnectOptions.MQTT_VERSION_3_1_1); //版本options.setUserName("xjs1919");options.setPassword("123321".toCharArray());// client.setManualAcks(true);client.connect(options);//连接//订阅topicclient.subscribe("demoTopic", 2);// 设置回调，将来收到消息的时候会被回调client.setCallback(new MqttCallbackExtended() {@Overridepublic void connectComplete(boolean reconnect, String serverURI) {System.out.println("连接完成");}@Overridepublic void connectionLost(Throwable cause) {System.out.println("连接丢失");}@Overridepublic void messageArrived(String topic, MqttMessage message) throws Exception {System.out.println("收到消息，topic："+topic + ", msg:" + new String(message.getPayload()));//client.messageArrivedComplete(message.getId(),message.getQos());}@Overridepublic void deliveryComplete(IMqttDeliveryToken token) {// Qos0: 当消息发送出去就回调// Qos1: 当发送者收到了puback的时候的回调// Qos2: 当发送者收到了pubcomp的时候的回调System.out.println("消息发送完成");}});client.publish("demoTopic", "hello,这是一个测试消息!".getBytes(), 2, false);return "ok";}}

参考文章：
https://www.cnblogs.com/motion/p/14974024.html
https://blog.csdn.net/u013615903/article/details/131395264