Deserializing different JSON payload from same Kafka topic with Spring Kafka

Question

I\'m trying to deserialize different JSON payloads from the same Kafka topic. The other questions asked here, guided me to a first attempt, but I was not able to get it runn

Answer 1

You can't do that; you have 2 different listener containers with listeners that expect different objects.

For multiple listener methods that receive different types, you need to use @KafkaListener at the class level and @KafkaHandler at the method level.

See @KafkaListener on a Class.

When using @KafkaListener at the class-level, you specify @KafkaHandler at the method level. When messages are delivered, the converted message payload type is used to determine which method to call.

@KafkaListener(id = "multi", topics = "myTopic")
static class MultiListenerBean {

    @KafkaHandler
    public void listen(String foo) {
        ...
    }

    @KafkaHandler
    public void listen(Integer bar) {
        ...
    }

    @KafkaHandler(isDefault = true`)
    public void listenDefault(Object object) {
        ...
    }

}

The default method is optional and is used for unknown payload types.

But this only works with a smart deserializer (that knows how to convert to different payloads).

Or, you can add a RecordFilterStrategy to the listener container factory to skip the other records in each listener.