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BAEL-6416 | Article code (#14065)

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Avin Buricha 2023-05-31 08:53:46 +05:30 committed by GitHub
parent 9834fe1d21
commit 23917a110b
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81
apache-kafka-2/src/main/java/com/baeldung/kafka/consumer/ConsumeFromBeginning.java Normal file
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package com.baeldung.kafka.consumer;
import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;
import java.util.UUID;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
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.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.kafka.common.serialization.StringSerializer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class ConsumeFromBeginning {
private static Logger logger = LoggerFactory.getLogger(ConsumeFromBeginning.class);
private static String TOPIC = "baeldung";
private static int messagesInTopic = 10;
private static KafkaProducer<String, String> producer;
private static KafkaConsumer<String, String> consumer;
public static void main(String[] args) {
setup();
publishMessages();
consumeFromBeginning();
}
private static void consumeFromBeginning() {
consumer.subscribe(Arrays.asList(TOPIC));
ConsumerRecords<String, String> records = consumer.poll(Duration.ofSeconds(10));
for (ConsumerRecord<String, String> record : records) {
logger.info(record.value());
}
consumer.seekToBeginning(consumer.assignment());
records = consumer.poll(Duration.ofSeconds(10));
for (ConsumerRecord<String, String> record : records) {
logger.info(record.value());
}
}
private static void publishMessages() {
for (int i = 1; i <= messagesInTopic; i++) {
ProducerRecord<String, String> record = new ProducerRecord<>(TOPIC, String.valueOf(i));
producer.send(record);
}
}
private static void setup() {
Properties producerProperties = new Properties();
producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
Properties consumerProperties = new Properties();
consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, UUID.randomUUID()
.toString());
producer = new KafkaProducer<>(producerProperties);
consumer = new KafkaConsumer<>(consumerProperties);
}
}

109
apache-kafka-2/src/test/java/com/baeldung/kafka/consumer/ConsumeFromBeginningLiveTest.java Normal file
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package com.baeldung.kafka.consumer;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;
import java.util.UUID;
import java.util.concurrent.ExecutionException;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
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.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.kafka.common.serialization.StringSerializer;
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.testcontainers.containers.KafkaContainer;
import org.testcontainers.junit.jupiter.Container;
import org.testcontainers.junit.jupiter.Testcontainers;
import org.testcontainers.utility.DockerImageName;
// This live test needs a Docker Daemon running so that a kafka container can be created
@Testcontainers
public class ConsumeFromBeginningLiveTest {
private static Logger logger = LoggerFactory.getLogger(ConsumeFromBeginningLiveTest.class);
private static String TOPIC = "baeldung";
private static int messagesInTopic = 10;
private static KafkaProducer<String, String> producer;
private static KafkaConsumer<String, String> consumer;
@Container
private static final KafkaContainer KAFKA_CONTAINER = new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:latest"));
@BeforeAll
static void setup() {
KAFKA_CONTAINER.addExposedPort(9092);
Properties producerProperties = new Properties();
producerProperties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
producerProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
producerProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
Properties consumerProperties = new Properties();
consumerProperties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, KAFKA_CONTAINER.getBootstrapServers());
consumerProperties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumerProperties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
consumerProperties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
consumerProperties.put(ConsumerConfig.GROUP_ID_CONFIG, UUID.randomUUID()
.toString());
producer = new KafkaProducer<>(producerProperties);
consumer = new KafkaConsumer<>(consumerProperties);
}
private static void publishMessages() throws ExecutionException, InterruptedException {
for (int i = 1; i <= messagesInTopic; i++) {
ProducerRecord<String, String> record = new ProducerRecord<>(TOPIC, String.valueOf(i));
producer.send(record)
.get();
}
}
@AfterAll
static void destroy() {
KAFKA_CONTAINER.stop();
}
@Test
void givenMessages_whenConsumedFromBeginning_thenCheckIfConsumedFromBeginning() throws ExecutionException, InterruptedException {
publishMessages();
consumer.subscribe(Arrays.asList(TOPIC));
ConsumerRecords<String, String> records = consumer.poll(Duration.ofSeconds(10));
int messageCount = 0;
for (ConsumerRecord<String, String> record : records) {
logger.info(record.value());
messageCount++;
}
assertEquals(messagesInTopic, messageCount);
consumer.seekToBeginning(consumer.assignment());
records = consumer.poll(Duration.ofSeconds(10));
messageCount = 0;
for (ConsumerRecord<String, String> record : records) {
logger.info(record.value());
messageCount++;
}
assertEquals(messagesInTopic, messageCount);
}
}