package MQTT; import org.eclipse.paho.client.mqttv3.*; public class PubExampleCallback { public static void main(String[] args) { MqttClient client; String broker = "tcp://localhost:1883"; String clientId = MqttClient.generateClientId(); String topic = "home/sensors/temp"; int qos = 2; try { client = new MqttClient(broker, clientId); MqttConnectOptions connOpts = new MqttConnectOptions(); connOpts.setCleanSession(true); // Connect the client System.out.println(clientId + " Connecting Broker " + broker); client.connect(connOpts); System.out.println(clientId + " Connected - Thread PID: " + Thread.currentThread().getId()); // Callback client.setCallback(new MqttCallback() { public void messageArrived(String topic, MqttMessage message) { // Not used Here } public void connectionLost(Throwable cause) { System.out.println(clientId + " Connectionlost! cause:" + cause.getMessage()); } public void deliveryComplete(IMqttDeliveryToken token) { // Until the delivery is completed, messages with QoS 1 or 2 are retained from the client // Delivery for a message is completed when all acknowledgments have been received // When the callback returns from deliveryComplete to the main thread, the client removes the retained messages with QoS 1 or 2. if (token.isComplete()) { System.out.println(clientId + " Message delivered - Thread PID: " + Thread.currentThread().getId()); } } }); String payload = String.valueOf(0 + (Math.random() * 10)); // create a random number between 0 and 10 MqttMessage message = new MqttMessage(payload.getBytes()); // Set the QoS on the Message message.setQos(qos); System.out.println(clientId + " Publishing message: " + payload + " ..."); client.publish(topic, message); System.out.println(clientId + " Message published - Thread PID: " + Thread.currentThread().getId()); if (client.isConnected()) client.disconnect(); System.out.println("Publisher " + clientId + " disconnected - Thread PID: " + Thread.currentThread().getId()); } catch (MqttException me ) { System.out.println("reason " + 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); me.printStackTrace(); } } }