package de.juplo.kafka;
+import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
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.common.errors.WakeupException;
-import org.apache.kafka.common.serialization.StringDeserializer;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.kafka.annotation.KafkaListener;
+import org.springframework.kafka.config.KafkaListenerEndpointRegistry;
+import org.springframework.stereotype.Component;
-import java.time.Duration;
-import java.util.Arrays;
-import java.util.Properties;
-import java.util.concurrent.locks.Condition;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
+import javax.annotation.PreDestroy;
+import java.util.List;
+import java.util.function.Consumer;
+@Component
@Slf4j
-public class SimpleConsumer
+@RequiredArgsConstructor
+public class EndlessConsumer<K, V>
{
+ @Autowired
+ private KafkaListenerEndpointRegistry registry;
+ @Value("${consumer.client-id}")
+ String id;
+ @Autowired
+ Consumer<ConsumerRecord<K, V>> handler;
+
private long consumed = 0;
- private KafkaConsumer<String, String> consumer;
- private Lock lock = new ReentrantLock();
- private Condition stopped = lock.newCondition();
+
+ @KafkaListener(
+ id = "${consumer.client-id}",
+ idIsGroup = false,
+ topics = "${consumer.topic}",
+ containerFactory = "batchFactory",
+ autoStartup = "false")
+ public void receive(List<ConsumerRecord<K, V>> records)
+ {
+ // Do something with the data...
+ log.info("{} - Received {} messages", id, records.size());
+ for (ConsumerRecord<K, V> record : records)
+ {
+ log.info(
+ "{} - {}: {}/{} - {}={}",
+ id,
+ record.offset(),
+ record.topic(),
+ record.partition(),
+ record.key(),
+ record.value()
+ );
+
+ handler.accept(record);
+
+ consumed++;
+ }
+ }
- public SimpleConsumer()
+ public synchronized void start()
{
- // tag::create[]
- Properties props = new Properties();
- props.put("bootstrap.servers", ":9092");
- props.put("group.id", "my-consumer"); // << Used for Offset-Commits
- // end::create[]
- props.put("auto.offset.reset", "earliest");
- // tag::create[]
- props.put("key.deserializer", StringDeserializer.class.getName());
- props.put("value.deserializer", StringDeserializer.class.getName());
+ if (registry.getListenerContainer(id).isChildRunning())
+ throw new IllegalStateException("Consumer instance " + id + " is already running!");
- KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
- // end::create[]
- this.consumer = consumer;
+ log.info("{} - Starting - consumed {} messages before", id, consumed);
+ registry.getListenerContainer(id).start();
}
-
- public void run()
+ public synchronized void stop()
{
- String id = "C";
+ if (!registry.getListenerContainer(id).isChildRunning())
+ throw new IllegalStateException("Consumer instance " + id + " is not running!");
+ log.info("{} - Stopping", id);
+ registry.getListenerContainer(id).stop();
+ log.info("{} - Stopped - consumed {} messages so far", id, consumed);
+ }
+
+ @PreDestroy
+ public void destroy()
+ {
+ log.info("{} - Destroy!", id);
try
{
- log.info("{} - Subscribing to topic test", id);
- consumer.subscribe(Arrays.asList("test"));
-
- // tag::loop[]
- while (true)
- {
- ConsumerRecords<String, String> records =
- consumer.poll(Duration.ofSeconds(1));
-
- // Do something with the data...
- // end::loop[]
- 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()
- );
- }
- // tag::loop[]
- }
- // end::loop[]
+ stop();
}
- catch(WakeupException e)
+ catch (IllegalStateException e)
{
- log.info("{} - RIIING!", id);
+ log.info("{} - Was already stopped", id);
}
- catch(Exception e)
+ catch (Exception e)
{
- log.error("{} - Unexpected error: {}", id, e.toString());
+ log.error("{} - Unexpected exception while trying to stop the consumer", id, e);
}
finally
{
- this.lock.lock();
- try
- {
- log.info("{} - Closing the KafkaConsumer", id);
- consumer.close();
- log.info("C - DONE!");
- stopped.signal();
- }
- finally
- {
- this.lock.unlock();
- log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
- }
+ log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
}
}
-
-
- public static void main(String[] args) throws Exception
- {
- SimpleConsumer instance = new SimpleConsumer();
-
- Runtime.getRuntime().addShutdownHook(new Thread(() ->
- {
- instance.lock.lock();
- try
- {
- instance.consumer.wakeup();
- instance.stopped.await();
- }
- catch (InterruptedException e)
- {
- log.warn("Interrrupted while waiting for the consumer to stop!", e);
- }
- finally
- {
- instance.lock.unlock();
- }
- }));
-
- instance.run();
- }
}