jackson - Convert String from mqtt to Object with Spring Integration

Question

I want to convert received message from mqtt-servet to an java object. I couldn't find a hint how it is possible with spring-integration tools. Here is the code

@Bean
  public MqttPahoClientFactory mqttClientFactory() {
    DefaultMqttPahoClientFactory factory = new DefaultMqttPahoClientFactory();
    MqttConnectOptions options = new MqttConnectOptions();
    
    options.setServerURIs(new String[] 
    { 
      "ssl://"+this.hostname+":"+this.port, 
    }
    );
    options.setUserName(this.username);
    options.setPassword(this.password.toCharArray());
    factory.setConnectionOptions(options);
    return factory;
  }
@Bean
  public MessageProducer inboundSendorData() {
    String clientId = "Java_" + UUID.randomUUID().toString();
    MqttPahoMessageDrivenChannelAdapter adapter = new MqttPahoMessageDrivenChannelAdapter(
      clientId,
      this.mqttClientFactory(),
      "sensordata"
    );
    //DefaultPahoMessageConverter converter = new DefaultPahoMessageConverter();
    //adapter.setConverter(converter);
    adapter.setCompletionTimeout(5000);
    adapter.setConverter(new DefaultPahoMessageConverter());
    adapter.setQos(1);
    adapter.setOutputChannel(mqttInputChannelSensorData());

    return adapter;
  }

  @Bean
  public MessageChannel mqttInputChannelSensorData() {
      return new DirectChannel();
  }

  @Bean
  @ServiceActivator(inputChannel = "mqttInputChannelSensorData")
  public MessageHandler handlerSensorData() {
    return new MqttSubSensorHandler();
  }

Here is the code for the Handler

public class MqttSubSensorHandler implements MessageHandler {
  @Autowired
  private SensorRepository sensorRepository;

  @Autowired
  public MqttSubSensorHandler(SensorRepository sensorRepository) {
    this.sensorRepository = sensorRepository;
  }

  public MqttSubSensorHandler() {
  }

  public void handleResponse(Message<?> message) {

  }

  @Override
  public void handleMessage(Message<?> message) throws MessagingException {
    System.out.println(message.getPayload());
    
  }
} 

I assume it is possible, because it is possible with Spring JMS. And the approach for setting up the JMS connection is pretty similar.

question from:https://stackoverflow.com/questions/65941510/convert-string-from-mqtt-to-object-with-spring-integration

Answer 1

The DefaultPahoMessageConverter can be supplied with any BytesMessageMapper, where one of them is ConvertingBytesMessageMapper. Which, in turn, you can supply with any MessageConverter impl, e.g. MappingJackson2MessageConverter.