Apache Kafka Java code for Producer and Consumer

Create project and convert to maven project.
Add below dependancy entry in pom.xml.

<dependencies>
  <dependency>
      <groupId>org.apache.kafka</groupId>
      <artifactId>kafka-clients</artifactId>
      <version>2.5.0</version>
   </dependency> 
 </dependencies>

To create the topic here is the commnd.
kafka-topics --create --topic ani-topic --partitions 1 --replication-factor 1 --zookeeper localhost:2181

Make sure u created topic before proceeding-ani-topic.

Make sure zookeeper and kafka servers are running.
Producer Code

import java.util.Properties;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringSerializer;

public class SimpleSender {

	public static void main(String[] args) {
		Properties props=new Properties();
		props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
		props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
		props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
		
		KafkaProducer producer=new KafkaProducer<>(props);
		
		String topic="ani-topic";
		for(int i=1;i<=10;i++) {
			ProducerRecord record=new ProducerRecord(topic,
					"test-key", "This is a test message "+i);
			producer.send(record);
		}
			
		System.out.println("messages sent");
		producer.close();
	}
}

Consumer Code

import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Properties;

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.kafka.common.serialization.StringSerializer;

public class SimpleRreceiver {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Properties props=new Properties();
		props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
		props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
		props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
		props.put(ConsumerConfig.GROUP_ID_CONFIG, "group-6");
		props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
		
		KafkaConsumer consumer=new KafkaConsumer<>(props);
		
		String topic="ani-topic";

		List topics=Collections.singletonList(topic);
		consumer.subscribe(topics);
		System.out.println("waiting for messages ");
		while(true) {
			ConsumerRecords records=consumer.poll(Duration.ofSeconds(30));
			records.forEach(record->System.out.println("key:"+record.key()+"\tvalue: "+record.value()
			+"\tpartition: "+record.partition()));
		}
		
	}

}

Run Consumer, can see waiting message.



Start Producer, messages will be sent consumer.



Message delivered to partition 0.