springboot怎么整合mqtt，需要详细步骤

在Spring Boot中使用MQTT，需要进行以下步骤：

步骤1：添加依赖

添加paho-mqtt-client依赖，可以在Maven或Gradle中添加：

Maven：

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

Gradle：

dependencies {
    implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.5'
}

步骤2：设置MQTT连接参数

在`application.properties`文件中设置MQTT连接参数，例如：

mqtt.broker.url=tcp://localhost:1883
mqtt.client.username=user
mqtt.client.password=pass
mqtt.topic=topic/test

步骤3：创建MQTT客户端

在Spring Boot应用程序中创建MQTT客户端，例如：

@Configuration
public class MqttClientConfig {
    @Autowired
    private MqttProperties mqttProperties;

    @Bean
    public MqttClient mqttClient() throws MqttException {
        MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
        mqttConnectOptions.setUserName(mqttProperties.getClient().getUsername());
        mqttConnectOptions.setPassword(mqttProperties.getClient().getPassword().toCharArray());
        mqttConnectOptions.setConnectionTimeout(mqttProperties.getTimeout());
        mqttConnectOptions.setKeepAliveInterval(mqttProperties.getKeepAlive());

        MqttClient mqttClient = new MqttClient(mqttProperties.getBroker().getUrl(), MqttClient.generateClientId());
        mqttClient.connect(mqttConnectOptions);

        return mqttClient;
    }
}

步骤4：发布消息

在需要发布MQTT消息的地方使用MQTT客户端，例如：

@Service
public class SomeService {
    @Autowired
    private MqttClient mqttClient;
    @Autowired
    private MqttProperties mqttProperties;

    public void publishMessage(String message) throws MqttException {
        MqttMessage mqttMessage = new MqttMessage(message.getBytes());
        mqttMessage.setQos(mqttProperties.getQos());
        mqttClient.publish(mqttProperties.getTopic(), mqttMessage);
    }
}

步骤5：订阅消息

创建消息监听器，例如：

@Component
public class MqttMessageListener implements MqttCallback {
    @Override
    public void connectionLost(Throwable cause) { }

    @Override
    public void messageArrived(String topic, MqttMessage message) throws Exception {
        System.out.println("Message received: " + new String(message.getPayload()));
    }

    @Override
    public void deliveryComplete(IMqttDeliveryToken token) { }
}

在MQTT客户端中添加消息监听器，例如：

@Configuration
public class MqttClientConfig {
    // ...

    @Autowired
    private MqttMessageListener mqttMessageListener;

    @Bean
    public MqttClient mqttClient() throws MqttException {
        // ...

        mqttClient.setCallback(mqttMessageListener);

        return mqttClient;
    }
}

订阅指定主题，例如：

@Service
public class SomeService {
    @Autowired
    private MqttClient mqttClient;
    @Autowired
    private MqttProperties mqttProperties;
    @Autowired
    private MqttMessageListener mqttMessageListener;

    public void subscribeToTopic() throws MqttException {
        mqttClient.subscribe(mqttProperties.getTopic(), mqttProperties.getQos(), mqttMessageListener);
    }
}

这些就是在Spring Boot中整合MQTT的基本步骤。