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 import org.springframework.scheduling.annotation.Async;
  10
  11 import java.time.Duration;
  12 import java.util.Arrays;
  13
  14
  15 @Slf4j
  16 @RequiredArgsConstructor
  17 public class SimpleConsumer
  18 {
  19   private final String id;
  20   private final String topic;
  21   private final Consumer<String, String> consumer;
  22
  23   private volatile boolean running = false;
  24   private long consumed = 0;
  25
  26
  27   @Async
  28   public void run()
  29   {
  30     try
  31     {
  32       log.info("{} - Subscribing to topic test", id);
  33       consumer.subscribe(Arrays.asList(topic));
  34       running = true;
  35
  36       while (true)
  37       {
  38         ConsumerRecords<String, String> records =
  39             consumer.poll(Duration.ofSeconds(1));
  40
  41         log.info("{} - Received {} messages", id, records.count());
  42         for (ConsumerRecord<String, String> record : records)
  43         {
  44           consumed++;
  45           log.info(
  46               "{} - {}: {}/{} - {}={}",
  47               id,
  48               record.offset(),
  49               record.topic(),
  50               record.partition(),
  51               record.key(),
  52               record.value()
  53           );
  54         }
  55       }
  56     }
  57     catch(WakeupException e)
  58     {
  59       log.info("{} - Consumer was signaled to finish its work", id);
  60     }
  61     catch(Exception e)
  62     {
  63       log.error("{} - Unexpected error: {}, unsubscribing!", id, e.toString());
  64       consumer.unsubscribe();
  65     }
  66     finally
  67     {
  68       running = false;
  69       log.info("{} - Closing the KafkaConsumer", id);
  70       consumer.close();
  71       log.info("{}: Consumed {} messages in total, exiting!", id, consumed);
  72     }
  73   }
  74
  75   public boolean isRunning()
  76   {
  77     return running;
  78   }
  79 }