package com.example.kafka;

import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.Properties;

public class KafkaProducerWithKey {
    public static void main(String[] args) {
        System.out.println("My first Kafka Producer");

        String bootstrapServers = "kafka1:9092";
        String myKey = "anyString";
        String myMessage = "anyMessage";

        // create Producer properties
        Properties properties = new Properties();
        properties.setProperty(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        properties.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        properties.setProperty(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());

        // create the producer
        KafkaProducer<String, String> producer = new KafkaProducer<String, String>(properties);

        // create a producer record
        for (int i=0; i<10; i++ ) {
            ProducerRecord<String, String> record =
                    new ProducerRecord<String, String>("my-topic1", myKey, "Java message "+i);

            // send data - asynchronous
            producer.send(record, new Callback() {
                public void onCompletion(RecordMetadata recordMetadata, Exception e) {
                    if (e == null) {
                        System.out.println("Partition: " + recordMetadata.partition() + "    " +
                                           "Offset: " + recordMetadata.offset());

                    } else {
                        System.out.println("Error: " + e);
                    }
                }
            });
        }

        // Flush data - data is sent
        producer.flush();

        // Flush and Close the producer
        producer.close();

        System.out.println("The producer has been closed.");
    }
}