package de.juplo.kafka;
import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.clients.producer.Producer;
-import org.apache.kafka.clients.producer.KafkaProducer;
-import org.apache.kafka.clients.producer.ProducerRecord;
-import org.apache.kafka.common.serialization.StringSerializer;
-
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.errors.WakeupException;
+import org.apache.kafka.common.serialization.StringDeserializer;
+
+import java.time.Duration;
+import java.util.Arrays;
import java.util.Properties;
@Slf4j
-public class ExampleProducer
+public class ExampleConsumer
{
private final String id;
private final String topic;
- private final Producer<String, String> producer;
+ private final Consumer<String, String> consumer;
- private volatile boolean running = true;
- private volatile boolean done = false;
- private long produced = 0;
+ private volatile boolean running = false;
+ private long consumed = 0;
- public ExampleProducer(
+ public ExampleConsumer(
String broker,
String topic,
+ String groupId,
String clientId)
{
Properties props = new Properties();
props.put("bootstrap.servers", broker);
+ props.put("group.id", groupId); // ID für die Offset-Commits
props.put("client.id", clientId); // Nur zur Wiedererkennung
- props.put("key.serializer", StringSerializer.class.getName());
- props.put("value.serializer", StringSerializer.class.getName());
+ props.put("auto.offset.reset", "earliest"); // Von Beginn an lesen
+ props.put("partition.assignment.strategy", "org.apache.kafka.clients.consumer.CooperativeStickyAssignor");
+ props.put("key.deserializer", StringDeserializer.class.getName());
+ props.put("value.deserializer", StringDeserializer.class.getName());
this.id = clientId;
this.topic = topic;
- producer = new KafkaProducer<>(props);
+ consumer = new KafkaConsumer<>(props);
}
+
public void run()
{
- long i = 0;
-
try
{
- for (; running; i++)
+ log.info("{} - Subscribing to topic {}", id, topic);
+ consumer.subscribe(Arrays.asList(topic));
+ running = true;
+
+ while (true)
{
- send(Long.toString(i%10), Long.toString(i));
- Thread.sleep(500);
+ ConsumerRecords<String, String> records = consumer.poll(Duration.ofSeconds(1));
+
+ log.info("{} - Received {} messages", id, records.count());
+ for (ConsumerRecord<String, String> record : records)
+ {
+ consumed++;
+ log.info(
+ "{} - {}: {}/{} - {}={}",
+ id,
+ record.offset(),
+ record.topic(),
+ record.partition(),
+ record.key(),
+ record.value()
+ );
+ }
}
}
- catch (Exception e)
+ catch(WakeupException e)
{
- log.error("{} - Unexpected error!", id, e);
+ log.info("{} - Consumer was signaled to finish its work", id);
}
- finally
+ catch(Exception e)
{
- log.info("{}: Closing the KafkaProducer", id);
- producer.close();
- log.info("{}: Produced {} messages in total, exiting!", id, produced);
- done = true;
+ log.error("{} - Unexpected error, unsubscribing!", id, e);
+ consumer.unsubscribe();
}
- }
-
- void send(String key, String value)
- {
- final long sendRequested = System.currentTimeMillis();
-
- final ProducerRecord<String, String> record = new ProducerRecord<>(
- topic, // Topic
- key, // Key
- value // Value
- );
-
- producer.send(record, (metadata, e) ->
+ finally
{
- long sendRequestProcessed = System.currentTimeMillis();
- if (e == null)
- {
- // HANDLE SUCCESS
- log.debug(
- "{} - Sent message {}={}, partition={}, offset={}, timestamp={}, latency={}ms",
- id,
- key,
- value,
- metadata.partition(),
- metadata.offset(),
- metadata.timestamp(),
- sendRequestProcessed - sendRequested
- );
- }
- else
- {
- // HANDLE ERROR
- log.error(
- "{} - ERROR for message {}={}, latency={}ms: {}",
- id,
- key,
- value,
- sendRequestProcessed - sendRequested,
- e.toString()
- );
- }
- });
-
- long sendRequestQueued = System.currentTimeMillis();
- produced++;
- log.trace(
- "{} - Queued message {}={}, latency={}ms",
- id,
- key,
- value,
- sendRequestQueued - sendRequested
- );
+ running = false;
+ log.info("{} - Closing the KafkaConsumer", id);
+ consumer.close();
+ log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
+ }
}
public static void main(String[] args) throws Exception
{
- if (args.length != 3)
+ String broker = ":9092";
+ String topic = "test";
+ String groupId = "my-group";
+ String clientId = "DEV";
+
+ switch (args.length)
{
- log.error("Three arguments required!");
- log.error("arg[0]: Broker-Address");
- log.error("arg[1]: Topic");
- log.error("arg[2]: Unique Client-ID");
- System.exit(1);
- return;
+ case 4:
+ clientId = args[3];
+ case 3:
+ groupId = args[2];
+ case 2:
+ topic = args[1];
+ case 1:
+ broker = args[0];
}
- log.info(
- "Running ExampleProducer: broker={}, topic={}, client-id={}",
- args[0],
- args[1],
- args[2]);
- ExampleProducer instance = new ExampleProducer(args[0], args[1], args[2]);
+ ExampleConsumer instance = new ExampleConsumer(broker, topic, groupId, clientId);
Runtime.getRuntime().addShutdownHook(new Thread(() ->
{
- instance.running = false;
- while (!instance.done)
+ instance.consumer.wakeup();
+
+ while (instance.running)
{
log.info("{} - Waiting for main-thread...", instance.id);
try
log.info("{} - Shutdown completed.", instance.id);
}));
+ log.info(
+ "Running ExampleConsumer: broker={}, topic={}, group-id={}, client-id={}",
+ broker,
+ topic,
+ groupId,
+ clientId);
instance.run();
}
}
projects / demos / kafka / training / commitdiff