MQTT mit Java

mqtt.java

package mmbbs;

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.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;

public class MQTT {
    public static void main(String[] args) {
        MqttClient client;
        try {
            client = new MqttClient("tcp://service.joerg-tuttas.de", "clientId");
            client.connect();
            System.out.println("Connected");
            client.setCallback(new MqttCallback() {

				public void connectionLost(Throwable cause) {
                    System.out.println("Connection Lost");
					
				}

				public void messageArrived(String topic, MqttMessage message) throws Exception {
					System.out.println("Message arived topic:"+topic+" message:"+message.toString());
				}

				public void deliveryComplete(IMqttDeliveryToken token) {
					System.out.println("deliveryCompleted");
				}
               

            });
            client.subscribe("esp32/temp");
            while(true) {

            }
        } catch (MqttException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

Zu installieren via Maven im pom.xml

    <dependency>
        <groupId>org.eclipse.paho</groupId>
        <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
        <version>1.0.2</version>
    </dependency>