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MQTT Asynchronous Subscriber Client Sample based on
package mqtt.demo;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttAsyncClient;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
public class MqttSubscribeSample implements MqttCallback {
public static void main(String[] args) {
String topic = "MQTT Examples";
int qos = 2;
String broker = "tcp://localhost:1883";
String clientId = "JavaAsyncSample";
MemoryPersistence persistence = new MemoryPersistence();
try {
MqttAsyncClient sampleClient = new MqttAsyncClient(broker, clientId, persistence);
MqttConnectOptions connOpts = new MqttConnectOptions();
sampleClient.setCallback(new MqttSubscribeSample());
System.out.println("Connecting to broker: " + broker);
sampleClient.subscribe(topic, qos);
} catch (Exception me) {
if (me instanceof MqttException) {
System.out.println("reason " + ((MqttException) me).getReasonCode());
System.out.println("msg " + me.getMessage());
System.out.println("loc " + me.getLocalizedMessage());
System.out.println("cause " + me.getCause());
System.out.println("excep " + me);
public void connectionLost(Throwable arg0) {
System.err.println("connection lost");
public void deliveryComplete(IMqttDeliveryToken arg0) {
System.err.println("delivery complete");
public void messageArrived(String topic, MqttMessage message) throws Exception {
System.out.println("topic: " + topic);
System.out.println("message: " + new String(message.getPayload()));
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