package com.example.test;

import example libraries

public class subscriber implements MqttCallback {

/** The broker url. */
private static final String brokerUrl = "tcp://example.com:1883";

/** The client id. */
private static final String clientId = "example.id";

private static final String USERNAME = "example";

private static final String PASSWORD = "example";

/** The topic. */
private static final String topic = "example/topic";


public static void main(String[] args) {

new subscriber().subscribe(topic);
}


public void subscribe(String topic) {

MemoryPersistence persistence = new MemoryPersistence();

try {

    MqttClient sampleClient = new MqttClient(brokerUrl, clientId,
 persistence);
    MqttConnectOptions connOpts = setUpConnectionOptions(USERNAME,
 PASSWORD);
    connOpts.setCleanSession(true);

    System.out.println("checking");

    System.out.println("Mqtt Connecting to broker: " + brokerUrl);
    sampleClient.connect(connOpts);
    System.out.println("Mqtt Connected");

    sampleClient.setCallback(this);
    sampleClient.subscribe(topic);

    System.out.println("Subscribed");
    System.out.println("Listening");


} catch (MqttException me) {

    System.out.println("Mqtt reason " + me.getReasonCode());
    System.out.println("Mqtt msg " + me.getMessage());
    System.out.println("Mqtt loc " + me.getLocalizedMessage());
    System.out.println("Mqtt cause " + me.getCause());
    System.out.println("Mqtt excep " + me);
    }
  }


private static MqttConnectOptions setUpConnectionOptions(String username,
 String password) {
MqttConnectOptions connOpts = new MqttConnectOptions();
connOpts.setCleanSession(true);
connOpts.setUserName(username);
connOpts.setPassword(password.toCharArray());
connOpts.setConnectionTimeout(10);
return connOpts;
}
public void connectionLost(Throwable arg0) {

}


public void deliveryComplete(IMqttDeliveryToken arg0) {

 }

public void messageArrived(String topic, MqttMessage message) throws Exception {

  System.out.println("Mqtt topic : " + topic);
  System.out.println("Mqtt msg : " + message.toString());
  String body = new String(message.getPayload());
  System.out.println("Mqtt msg : " + body);
  JSONObject objt1 = new JSONObject(message.getPayload());
  System.out.println(objt1);
}