juplo.de Git - demos/kafka/training/blob - src/main/java/de/juplo/kafka/SimpleConsumer.java

   1 package de.juplo.kafka;
   2
   3 import lombok.RequiredArgsConstructor;
   4 import lombok.extern.slf4j.Slf4j;
   5 import org.apache.kafka.clients.consumer.Consumer;
   6 import org.apache.kafka.clients.consumer.ConsumerRecord;
   7 import org.apache.kafka.clients.consumer.ConsumerRecords;
   8 import org.apache.kafka.common.errors.WakeupException;
   9
  10 import java.time.Duration;
  11 import java.util.Arrays;
  12
  13
  14 @Slf4j
  15 @RequiredArgsConstructor
  16 public class SimpleConsumer implements Runnable
  17 {
  18   private final String id;
  19   private final String topic;
  20   private final Consumer<String, String> consumer;
  21
  22   private long consumed = 0;
  23
  24
  25   @Override
  26   public void run()
  27   {
  28     try
  29     {
  30       log.info("{} - Subscribing to topic {}", id, topic);
  31       consumer.subscribe(Arrays.asList(topic));
  32
  33       while (true)
  34       {
  35         ConsumerRecords<String, String> records =
  36             consumer.poll(Duration.ofSeconds(1));
  37
  38         log.info("{} - Received {} messages", id, records.count());
  39         for (ConsumerRecord<String, String> record : records)
  40         {
  41           consumed++;
  42           log.info(
  43               "{} - {}: {}/{} - {}={}",
  44               id,
  45               record.offset(),
  46               record.topic(),
  47               record.partition(),
  48               record.key(),
  49               record.value()
  50           );
  51         }
  52       }
  53     }
  54     catch(WakeupException e)
  55     {
  56       log.info("{} - Consumer was signaled to finish its work", id);
  57     }
  58     catch(Exception e)
  59     {
  60       log.error("{} - Unexpected error: {}, unsubscribing!", id, e.toString());
  61       consumer.unsubscribe();
  62     }
  63     finally
  64     {
  65       log.info("{} - Closing the KafkaConsumer", id);
  66       consumer.close();
  67       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
  68     }
  69   }
  70 }