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;
13 import java.util.concurrent.locks.Condition;
14 import java.util.concurrent.locks.Lock;
15 import java.util.concurrent.locks.ReentrantLock;
19 public class SimpleConsumer
21 private long consumed = 0;
22 private KafkaConsumer<String, String> consumer;
23 private Lock lock = new ReentrantLock();
24 private Condition stopped = lock.newCondition();
27 public SimpleConsumer()
30 Properties props = new Properties();
31 props.put("bootstrap.servers", ":9092");
32 props.put("group.id", "my-consumer"); // << Used for Offset-Commits
34 props.put("auto.offset.reset", "earliest");
36 props.put("key.deserializer", StringDeserializer.class.getName());
37 props.put("value.deserializer", StringDeserializer.class.getName());
39 KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
41 this.consumer = consumer;
51 log.info("{} - Subscribing to topic test", id);
52 consumer.subscribe(Arrays.asList("test"));
57 ConsumerRecords<String, String> records =
58 consumer.poll(Duration.ofSeconds(1));
60 // Do something with the data...
62 log.info("{} - Received {} messages", id, records.count());
63 for (ConsumerRecord<String, String> record : records)
67 "{} - {}: {}/{} - {}={}",
80 catch(WakeupException e)
82 log.info("{} - RIIING!", id);
86 log.error("{} - Unexpected error: {}", id, e.toString());
93 log.info("{} - Closing the KafkaConsumer", id);
95 log.info("C - DONE!");
101 log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
107 public static void main(String[] args) throws Exception
109 SimpleConsumer instance = new SimpleConsumer();
111 Runtime.getRuntime().addShutdownHook(new Thread(() ->
113 instance.lock.lock();
116 instance.consumer.wakeup();
117 instance.stopped.await();
119 catch (InterruptedException e)
121 log.warn("Interrrupted while waiting for the consumer to stop!", e);
125 instance.lock.unlock();