1 package de.juplo.kafka;
3 import lombok.extern.slf4j.Slf4j;
4 import org.apache.kafka.clients.consumer.ConsumerRecord;
5 import org.apache.kafka.clients.consumer.ConsumerRecords;
6 import org.apache.kafka.clients.consumer.KafkaConsumer;
7 import org.apache.kafka.common.errors.WakeupException;
8 import org.apache.kafka.common.serialization.StringDeserializer;
10 import java.time.Duration;
11 import java.util.Arrays;
12 import java.util.Properties;
16 public class SimpleConsumer
18 private final String id;
19 private final String topic;
20 private final KafkaConsumer<String, String> consumer;
22 private volatile boolean running = false;
23 private long consumed = 0;
25 public SimpleConsumer(String broker, String topic, String groupId, String clientId)
27 Properties props = new Properties();
28 props.put("bootstrap.servers", broker);
29 props.put("group.id", groupId); // ID für die Offset-Commits
30 props.put("client.id", clientId); // Nur zur Wiedererkennung
31 props.put("auto.offset.reset", "earliest"); // Von Beginn an lesen
32 props.put("partition.assignment.strategy", "org.apache.kafka.clients.consumer.CooperativeStickyAssignor");
33 props.put("key.deserializer", StringDeserializer.class.getName());
34 props.put("value.deserializer", StringDeserializer.class.getName());
36 consumer = new KafkaConsumer<>(props);
47 log.info("{} - Subscribing to topic {}", id, topic);
48 consumer.subscribe(Arrays.asList(topic));
53 ConsumerRecords<String, String> records =
54 consumer.poll(Duration.ofSeconds(1));
56 log.info("{} - Received {} messages", id, records.count());
57 for (ConsumerRecord<String, String> record : records)
61 "{} - {}: {}/{} - {}={}",
72 catch(WakeupException e)
74 log.info("{} - Consumer was signaled to finish its work", id);
78 log.error("{} - Unexpected error: {}, unsubscribing!", id, e.toString());
79 consumer.unsubscribe();
84 log.info("{} - Closing the KafkaConsumer", id);
86 log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
91 public static void main(String[] args) throws Exception
93 String broker = ":9092";
94 String topic = "test";
95 String groupId = "my-group";
96 String clientId = "DEV";
111 SimpleConsumer instance = new SimpleConsumer(broker, topic, groupId, clientId);
113 Runtime.getRuntime().addShutdownHook(new Thread(() ->
115 instance.consumer.wakeup();
117 while (instance.running)
119 log.info("Waiting for main-thread...");
124 catch (InterruptedException e) {}
126 log.info("Shutdown completed.");
130 "Running SimpleConsumer: broker={}, topic={}, group-id={}, client-id={}",