How do you configure and use the Confluent Kafka Java client library?

The Confluent Kafka Java client library is a popular library for building Kafka applications in Java. It provides a set of high-level APIs that make it easy to produce and consume messages from Kafka topics, as well as manage Kafka clusters and topics. Here’s how you can configure and use the Confluent Kafka Java client library:

1. Add the dependency: To use the Confluent Kafka Java client library, you need to add the dependency to your project’s build file (such as pom.xml or build.gradle). The latest version of the library can be found on the Confluent website.

2. Create a producer: To create a Kafka producer using the Confluent Kafka Java client library, you can use the “KafkaProducer” class. You need to provide a set of properties that configure the producer, such as the bootstrap servers, key and value serializers, and any additional configuration options.

3. Create a consumer: To create a Kafka consumer using the Confluent Kafka Java client library, you can use the “KafkaConsumer” class. You need to provide a set of properties that configure the consumer, such as the bootstrap servers, group ID, key and value deserializers, and any additional configuration options.

4. Use the producer and consumer APIs: Once you have created a producer or consumer, you can use the high-level APIs provided by the Confluent Kafka Java client library to produce or consume messages from Kafka topics. These APIs provide a simple and intuitive interface for interacting with Kafka.

Here’s an example of how to configure and use the Confluent Kafka Java client library to create a Kafka producer and consumer:

Properties producerProps = new Properties();
producerProps.put("bootstrap.servers", "localhost:9092");
producerProps.put("key.serializer", StringSerializer.class.getName());
producerProps.put("value.serializer", StringSerializer.class.getName());

KafkaProducer producer = new KafkaProducer<>(producerProps);

ProducerRecord record = new ProducerRecord<>("my_topic", "my_key", "my_value");
producer.send(record);

producer.close();

Properties consumerProps = new Properties();
consumerProps.put("bootstrap.servers", "localhost:9092");
consumerProps.put("group.id", "my_group");
consumerProps.put("key.deserializer", StringDeserializer.class.getName());
consumerProps.put("value.deserializer", StringDeserializer.class.getName());

KafkaConsumer consumer = new KafkaConsumer<>(consumerProps);
consumer.subscribe(Collections.singletonList("my_topic"));

while (true) {
    ConsumerRecords records = consumer.poll(Duration.ofMillis(100));
    for (ConsumerRecord record : records) {
        System.out.println(record.key() + ": " + record.value());
    }
}

consumer.close();

In this example, we have defined the properties for the Kafka producer and consumer and created instances of the “KafkaProducer” and “KafkaConsumer” classes. We have used the producer to send a message to the “my_topic” topic and the consumer to read messages from the same topic.

By configuring and using the Confluent Kafka Java client library, you can build Kafka applications in Java with ease and take advantage of the many features and capabilities provided by the library.