Qfyilyi

I am struggling to send/receive the MQTT messages as JSON.

This is my code:

public class MainActivity extends AppCompatActivity {

    Gson gson = new Gson();



    public static final String BROKER_URL = "tcp://iot.eclipse.org:1883";





    String userid = "12345";  //

    //We have to generate a unique Client id.

    String clientId = userid + "-sub";



    // Default sensor to listen for -

    // Change to another if you are broadcasting a different sensor name

    String sensorname = "brightness";

    String sensorTemp = "temperature";



    String topicname = userid + "/" + sensorname;

    String topicname2 = userid + "/" + sensorTemp;

    public final String TOPIC_BRIGHTNESS = userid + "/brightness";

    public final String TOPIC_TEMPERATURE = userid + "/temperature";

    public final String TOPIC_DOORLOCK = userid + "/doorlock";

    private MqttClient mqttClient;

    Button publishTemperatureBtn;

    Switch publishDoorState;

    SeekBar tempSeekBar;

    TextView tempLabel;



    SensorData oneSensor = new SensorData("unknown", "unknown");

    String oneSensorJson = new String();



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        publishTemperatureBtn = (Button) findViewById(R.id.publishTemperatureBtnID);

        tempSeekBar = (SeekBar) findViewById(R.id.temperatureSeekBar);

        publishDoorState = (Switch) findViewById(R.id.doorSwitch);

        tempLabel = (TextView) findViewById(R.id.temperatureLabel);



        publishTemperatureBtn.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {

                // Code here executes on main thread after user presses button

                System.out.println("PUBLISHING");

                runOnUiThread(new Runnable() {

                    public void run() {

                        publishTemperature();

                    }

                });

            }

        });



        publishDoorState.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

            @Override

            public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {

                if (isChecked == true) {

                    runOnUiThread(new Runnable() {

                        @Override

                        public void run() {

                            publishDoorStateMethod_ON();

                        }

                    });

                } else if (isChecked == false) {

                    runOnUiThread(new Runnable() {

                        @Override

                        public void run() {

                            publishDoorStateMethod_OFF();

                        }

                    });

                }

            }

        });





        tempSeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

            @Override

            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {

                tempLabel.setText(i + "°C");

            }



            @Override

            public void onStartTrackingTouch(SeekBar seekBar) {



            }



            @Override

            public void onStopTrackingTouch(SeekBar seekBar) {

                runOnUiThread(new Runnable() {

                    @Override

                    public void run() {

                        publishTemperature();

                    }

                });

            }

        });





        // start new

        // Create MQTT client and start subscribing to message queue

        try {

            // change from original. Messages in "null" are not stored

            mqttClient = new MqttClient(BROKER_URL, clientId, null);

            mqttClient.setCallback(new MqttCallbackExtended() {

                @Override

                public void connectionLost(Throwable cause) {

                    //This is called when the connection is lost. We could reconnect here.

                }



                @Override

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

                    System.out.println("DEBUG: Message arrived. Topic: " + topic + "  Message: " + message.toString());

                    // get message data



                    final String messageStr = message.toString();



                    runOnUiThread(new Runnable() {

                        public void run() {

                            System.out.println("Updating UI");

                            // Update UI elements



                            if ((topic).equals(topicname)) {

                                System.err.println("Sensor gone!");

                                TextView sensorValueTV = (TextView) findViewById(R.id.sensorValueTV);

                                sensorValueTV.setText(messageStr);

                            } else if ((topic).equals(topicname2)) {

                                System.err.println("Sensor gone!");

                                TextView sensorTempValue = (TextView) findViewById(R.id.sensorTempValue);

                                sensorTempValue.setText(messageStr);

                            }





                        }

                    });



                }



                @Override

                public void deliveryComplete(IMqttDeliveryToken token) {

                    //no-op

                }



                @Override

                public void connectComplete(boolean b, String s) {

                    //no-op

                }

            });

        } catch (MqttException e) {

            e.printStackTrace();

            System.exit(1);

        }



        // temp use of ThreadPolicy until use AsyncTask

        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

        StrictMode.setThreadPolicy(policy);



        startSubscribing();





    }





    public void startSubscribing() {

        try {

            mqttClient.connect();



            //Subscribe to all subtopics of home

            final String topic = topicname;

            mqttClient.subscribe(topic);

            final String topic2 = topicname2;

            mqttClient.subscribe(topic2);



            System.out.println("Subscriber is now listening to " + topic);



        } catch (MqttException e) {

            e.printStackTrace();

            System.exit(1);

        }

    }



    public void publishTemperature() {

        try {

            final MqttTopic temperatureTopic = mqttClient.getTopic(TOPIC_TEMPERATURE);

            final int temperatureNumber = 30;

            EditText temperatureETValue = (EditText) findViewById(R.id.temperatureETValue);

            final String temperature = tempLabel.getText().toString();





            temperatureTopic.publish(new MqttMessage(temperature.getBytes()));



            System.out.println("Now publishing " + temperatureTopic);



        } catch (MqttException e) {

            e.printStackTrace();

            System.exit(1);

        }

    }



    public void publishDoorStateMethod_ON() {

        try {

            final MqttTopic doorButtonTopic = mqttClient.getTopic(TOPIC_DOORLOCK);

            String doorState;

            Button doorStateButton = (Button) findViewById(R.id.doorSwitch);

            doorState = "ON";

            doorButtonTopic.publish(new MqttMessage(doorState.getBytes()));



            System.out.println("Now publishing " + doorButtonTopic);

        } catch (MqttException e) {

            e.printStackTrace();

            System.exit(1);

        }

    }



    public void publishDoorStateMethod_OFF() {

        try {

            final MqttTopic doorButtonTopic = mqttClient.getTopic(TOPIC_DOORLOCK);

            String doorState;

            Button doorStateButton = (Button) findViewById(R.id.doorSwitch);

            doorState = "OFF";

            doorButtonTopic.publish(new MqttMessage(doorState.getBytes()));



            System.out.println("Now publishing " + doorButtonTopic);





        } catch (MqttException e) {

            e.printStackTrace();

            System.exit(1);

        }

    }

}

This is what I have been tasked to do:

1. Amend the Android code to send/receive the MQTT messages as json strings representing sensor objects. You will need to include the same SensorData object that you used in the Eclipse labs, and include the Gson class in your Android project. Use sample code from the Eclipse client/server labs to remind you how to create json objects from the SensorData object, and how to extract the object data when a json object arrives.

I already have my SensorData object. The examples in Elicpse that I have are no help whatsoever. Could someone please point me in the right direction.