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
  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   public void run()
  26   {
  27     try
  28     {
  29       log.info("{} - Subscribing to topic test", id);
  30       consumer.subscribe(Arrays.asList(topic));
  31
  32       while (true)
  33       {
  34         ConsumerRecords<String, String> records =
  35             consumer.poll(Duration.ofSeconds(1));
  36
  37         log.info("{} - Received {} messages", id, records.count());
  38         for (ConsumerRecord<String, String> record : records)
  39         {
  40           consumed++;
  41           log.info(
  42               "{} - {}: {}/{} - {}={}",
  43               id,
  44               record.offset(),
  45               record.topic(),
  46               record.partition(),
  47               record.key(),
  48               record.value()
  49           );
  50         }
  51       }
  52     }
  53     catch(WakeupException e)
  54     {
  55       log.info("{} - Consumer was signaled to finish its work", id);
  56     }
  57     catch(Exception e)
  58     {
  59       log.error("{} - Unexpected error: {}, unsubscribing!", id, e.toString());
  60       consumer.unsubscribe();
  61     }
  62     finally
  63     {
  64       log.info("{} - Closing the KafkaConsumer", id);
  65       consumer.close();
  66       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
  67     }
  68   }
  69 }