Se connecter au serveur MQTT

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Exemple de code

Java

Pour en savoir plus, consultez la documentation de référence de l'API Cloud IoT Core Java.

Pour vous authentifier auprès de Cloud IoT Core, configurez les Identifiants par défaut de l'application. Pour en savoir plus, consultez Configurer l'authentification pour un environnement de développement local.

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// Build the connection string for Google's Cloud IoT Core MQTT server. Only SSL
// connections are accepted. For server authentication, the JVM's root certificates
// are used.
final String mqttServerAddress =
    String.format("ssl://%s:%s", mqttBridgeHostname, mqttBridgePort);

// Create our MQTT client. The mqttClientId is a unique string that identifies this device. For
// Google Cloud IoT Core, it must be in the format below.
final String mqttClientId =
    String.format(
        "projects/%s/locations/%s/registries/%s/devices/%s",
        projectId, cloudRegion, registryId, gatewayId);

MqttConnectOptions connectOptions = new MqttConnectOptions();
// Note that the Google Cloud IoT Core only supports MQTT 3.1.1, and Paho requires that we
// explictly set this. If you don't set MQTT version, the server will immediately close its
// connection to your device.
connectOptions.setMqttVersion(MqttConnectOptions.MQTT_VERSION_3_1_1);

Properties sslProps = new Properties();
sslProps.setProperty("com.ibm.ssl.protocol", "TLSv1.2");
connectOptions.setSSLProperties(sslProps);

// With Google Cloud IoT Core, the username field is ignored, however it must be set for the
// Paho client library to send the password field. The password field is used to transmit a JWT
// to authorize the device.
connectOptions.setUserName("unused");

if ("RS256".equals(algorithm)) {
  connectOptions.setPassword(createJwtRsa(projectId, privateKeyFile).toCharArray());
} else if ("ES256".equals(algorithm)) {
  connectOptions.setPassword(createJwtEs(projectId, privateKeyFile).toCharArray());
} else {
  throw new IllegalArgumentException(
      "Invalid algorithm " + algorithm + ". Should be one of 'RS256' or 'ES256'.");
}

System.out.println(String.format("%s", mqttClientId));

// Create a client, and connect to the Google MQTT bridge.
try (MqttClient client =
    new MqttClient(mqttServerAddress, mqttClientId, new MemoryPersistence())) {
  // Both connect and publish operations may fail. If they do, allow retries but with an
  // exponential backoff time period.
  long initialConnectIntervalMillis = 500L;
  long maxConnectIntervalMillis = 6000L;
  long maxConnectRetryTimeElapsedMillis = 900000L;
  float intervalMultiplier = 1.5f;

  long retryIntervalMs = initialConnectIntervalMillis;
  long totalRetryTimeMs = 0;

  while (totalRetryTimeMs < maxConnectRetryTimeElapsedMillis && !client.isConnected()) {
    try {
      client.connect(connectOptions);
    } catch (MqttException e) {
      int reason = e.getReasonCode();

      // If the connection is lost or if the server cannot be connected, allow retries, but with
      // exponential backoff.
      System.out.println("An error occurred: " + e.getMessage());
      if (reason == MqttException.REASON_CODE_CONNECTION_LOST
          || reason == MqttException.REASON_CODE_SERVER_CONNECT_ERROR) {
        System.out.println("Retrying in " + retryIntervalMs / 1000.0 + " seconds.");
        Thread.sleep(retryIntervalMs);
        totalRetryTimeMs += retryIntervalMs;
        retryIntervalMs *= intervalMultiplier;
        if (retryIntervalMs > maxConnectIntervalMillis) {
          retryIntervalMs = maxConnectIntervalMillis;
        }
      } else {
        throw e;
      }
    }
  }

  attachCallback(client, gatewayId);

  // The topic gateways receive error updates on. QoS must be 0.
  String errorTopic = String.format("/devices/%s/errors", gatewayId);
  System.out.println(String.format("Listening on %s", errorTopic));

  client.subscribe(errorTopic, 0);

  return client;

Étapes suivantes

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