1
votes

I'm doing a project for my final University work. I want do a android app that comunicates with my raspberry pi using MQTT protocol. To do it I'm using a mosquitto broker, but when I publish message in a broker using the Java MQTT client using Eclipse Paho, my app publish the same message 5 times, and I don't know if the fault is of my class that publish message, or of my class on_create() of android.

My code is the following:

public class MainActivity extends AppCompatActivity implements    View.OnClickListener {
EditText distanceCondition;
EditText timeCondition;
EditText countCondition;

String distance;
String time;
String count;
String topic;

int notificationID = 1;
int functionality;
int ok = 1;

public void mqttconnect(final String topic, final String message){

    final MqttAndroidClient mqttAndroidClient = new MqttAndroidClient(this.getApplicationContext(), "tcp://192.168.1.36", "androidSampleClient");
    mqttAndroidClient.setCallback(new MqttCallback() {                                      //iot.eclipse.org:1883
        @Override
        public void connectionLost(Throwable cause) {
            System.out.println("Connection was lost!");

        }

        @Override
        public void messageArrived(String topic, MqttMessage message) throws Exception {
            System.out.println("Message Arrived!: " + topic + ": " + new String(message.getPayload()));
            //displayNotification("DETECT MOVEMENT! visit LCESS app now.");
            JSONObject inf = new JSONObject(Arrays.toString(message.getPayload()));
            try {
                if (inf.optString("Functionality").equals(6)) {
                    if (inf.optString("ok").equals(1)) {
                        displayNotification("DETECT MOVEMENT! visit LCESS app now.");
                    }
                }
                if (inf.optString("Functionality").equals(7)) {
                    if (inf.optString("ok").equals(1)) {
                        displayNotification("DETECT MOVEMENT IN" + inf.optString("Distance") + " CM! visit LCESS app now.");
                    }
                }
                if (inf.optString("Functionality").equals(8)) {
                    if (inf.optString("ok").equals(1)) {
                        displayNotification("DETECT MOVEMENT IN" + inf.optString("Time") + " HOURS! visit LCESS app now.");
                    }
                }
                if (inf.optString("Functionality").equals(9)) {
                    if (inf.optString("ok").equals(1)) {
                        displayNotification("DETECT MOVEMENT IN" + inf.optString("Distance") + " CM and in " + inf.optString("Time") + " HOURS! visit LCESS app now.");
                    }
                }
                if (inf.optString("Functionality").equals(10)) {
                    if (inf.optString("ok").equals(1)) {
                        displayNotification("DETECT " + inf.optString("Count") + " OBJECTS/PERSONS! visit LCESS app now.");
                    }
                }
            }
            catch (Exception functionality){

            }

        }

        @Override
        public void deliveryComplete(IMqttDeliveryToken token) {
            System.out.println("Delivery Complete!");
        }
    });

    try {
        mqttAndroidClient.connect(null, new IMqttActionListener() {
            @Override
            public void onSuccess(IMqttToken asyncActionToken) {
                System.out.println("Connection Success!");
                try {
                    System.out.println("Subscribing to: "+ topic);
                    mqttAndroidClient.subscribe(topic, 0);
                    System.out.println("Subscribed to: "+ topic);
                    System.out.println("Publishing message..");
                    mqttAndroidClient.publish(topic, new MqttMessage(message.getBytes()));
                } catch (MqttException ex) {
                }
            }

            @Override
            public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
                System.out.println("Connection Failure!");
            }
        });
    } catch (MqttException ex) {

    }


}

public JSONObject sendJSONmessage() {
    topic = "Mesurement";
    distance = distanceCondition.getText().toString();
    time = timeCondition.getText().toString();
    count = countCondition.getText().toString();

    JSONObject post_dict = new JSONObject();
    try {
        post_dict.put("Topic", topic);
        post_dict.put("ok" ,ok);
        post_dict.put("Functionality", functionality);
        post_dict.put("Distance", distance);
        post_dict.put("Time", time);
        post_dict.put("Count", count);

    } catch (JSONException e) {
        e.printStackTrace();
    }
    if (post_dict.length() > 0) {
        System.out.println(post_dict);
    }
    return post_dict;
}

protected void displayNotification(CharSequence contentText){
    Intent i = new Intent(this, NotificationActivity.class);
    i.putExtra("notificationID", notificationID);

    PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, i, 0);
    NotificationManager nm = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
    CharSequence ticker ="Notification in LCESS";
    CharSequence contentTitle = "LCESS";

    Notification noti = new NotificationCompat.Builder(this)
            .setContentIntent(pendingIntent)
            .setTicker(ticker)
            .setContentTitle(contentTitle)
            .setContentText(contentText)
            .setSmallIcon(R.drawable.lcess)
            .addAction(R.drawable.lcess, ticker, pendingIntent)
            .setVibrate(new long[] {100, 250, 100, 500})
            .build();
    nm.notify(notificationID, noti);
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    distanceCondition = (EditText) findViewById(R.id.edit_detectDistanceCondition);
    timeCondition = (EditText) findViewById(R.id.edit_detectTimeCondition);
    countCondition = (EditText) findViewById(R.id.edit_countDetects);

    Button button_detectDistance = (Button) findViewById(R.id.button_detectDistance);
    Button button_detectDistanceCondition = (Button) findViewById(R.id.button_detectDistanceCondition);
    Button button_detectTimeCondition = (Button) findViewById(R.id.button_detectTimeCondition);
    Button button_detectIfAllCondition = (Button) findViewById(R.id.button_detectIfAllCondition);
    Button button_count = (Button) findViewById(R.id.button_count);
    assert button_detectDistance != null;
    /*button_detectDistance.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            functionality = 1;
            mqttconnect("Device1/Detect", sendJSONmessage().toString());
        }
    });*/
    button_detectDistance.setOnClickListener(this);
    assert button_detectDistanceCondition != null;
    button_detectDistanceCondition.setOnClickListener(this);
    assert button_detectTimeCondition != null;
    button_detectTimeCondition.setOnClickListener(this);
    assert button_detectIfAllCondition != null;
    button_detectIfAllCondition.setOnClickListener(this);
    assert button_count != null;
    button_count.setOnClickListener(this);
}

public void onClick(View v){
    if (R.id.button_detectDistance==v.getId()){
        functionality = 1;
        mqttconnect("Mesurement", sendJSONmessage().toString());
    }
    else if (R.id.button_detectDistanceCondition==v.getId()){
        functionality = 2;
        mqttconnect(sendJSONmessage().optString(topic), sendJSONmessage().toString());
    }
    else if (R.id.button_detectTimeCondition==v.getId()){
        functionality = 3;
        mqttconnect(sendJSONmessage().optString(topic), sendJSONmessage().toString());
    }
    else if (R.id.button_detectIfAllCondition==v.getId()){
        functionality = 4;
        mqttconnect("Device1/Detect1", sendJSONmessage().toString());
    }
    else if (R.id.button_count==v.getId()){
        functionality = 5;
        mqttconnect("Device1/Detect1", sendJSONmessage().toString());
    }
}

}

First, I created the Mqtt class to publish and subscribe to the topic, After, the class to publish the message that I need in JSON format.

The next class I use it to display a notification. And finally, onCreate() and onClick classes where I declared my buttons, edittext... And where I put the conditions to publish a message. More concretly, when push a button, I publish a message in a topic with JSON format.

The App run well. But the question is: How I can publish ONLY one message in a broker?

In the following picture you can see how publish 5 message when I press the button. In red you can see the message published 5 or 6 times

2

2 Answers

0
votes

I resolved the problem. In this case how I build a function to connect with the broker, each time that I click some buttom I publish and subscribe again to the topic. and only I have to subscribe one time. The solution is connect to the broken and subscribe to the topic, only one time, thus we implement the same code but in onCreate() method.

0
votes
String msg = "{\"uuid\":\"12345678\"}";
MqttMessage m = new MqttMessage();
m.setPayload(msg.getBytes());
m.setQos(2);
m.setRetained(false);
mqttAndroidClient.publish(topic, m);