如何调用Properties 方法并将其设置到主类中？

Question

There's no error already, but when I run the program it fails to recognize the serializer which is inside the other class. Here's how it looks like.

public class Producer{

    private static final Logger logger = LogManager.getLogger(Producer.class);
    public static void main(String[] args) {
        logger.info("Creating Kafka Producer...");

        KafkaProducer<Integer, String> producer = new KafkaProducer<>(PropConfigs.prodProps());
        // The code above should run and call the PropConfigs (properties of kafka)

        logger.info("Start sending messages...");

        for (int i = 1; i <= AppConfigs.numEvents; i++) {
            producer.send(new ProducerRecord<>(AppConfigs.topicName, i, "Message " + i + " Test"), new Callback() {
                @Override
                public void onCompletion(RecordMetadata recordMetadata, Exception e) {
                    if(e == null){
                        logger.info("\nReceived metadata" + " Topic:" + recordMetadata.topic() + " Partition: " + recordMetadata.partition() + " Offset: " + recordMetadata.offset() + " Time: " + recordMetadata.timestamp() + "\n");
                    } else {
                        logger.error("Error", e);
                        e.printStackTrace();
                    }
                }
            });
        }

        logger.info("Finished - Closing Kafka Producer.");
        producer.flush();
        producer.close();

    }
}

Here's the PropConfigs class, where in I put the properties to be called from the main class Producer.

public class PropConfigs {


    public static Properties prodProps(){
        Properties props = new Properties();
        props.setProperty(ProducerConfig.CLIENT_ID_CONFIG, AppConfigs.applicationID);
        props.setProperty(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, AppConfigs.bootstrapServers);
        props.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, IntegerSerializer.class.getName());
        props.setProperty(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        props.setProperty(ProducerConfig.ACKS_CONFIG, "all");
        props.setProperty(ProducerConfig.RETRIES_CONFIG, "3");
        props.setProperty(ProducerConfig.MAX_IN_FLIGHT_REQUESTS_PER_CONNECTION, "5");

        return new Properties(props);
    }

}

Whenever I run it, like I said it fails to recognize the properties that I set.

Answer 1

You mean it fails to recognize the prodProps method ? (You have no custom serializer here). Note: You can have this return props

You've not shown your import statements, but make sure the classes are in the same package (and not the default package, or no package)

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If you really want to externalize the properties, Spring-Boot / Spring-Kafka are commonly used to do so