juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java

   1 package de.juplo.kafka.wordcount.top10;
   2
   3 import com.fasterxml.jackson.databind.ObjectMapper;
   4 import lombok.extern.slf4j.Slf4j;
   5 import org.apache.kafka.streams.KafkaStreams;
   6 import org.apache.kafka.streams.KeyValue;
   7 import org.apache.kafka.streams.StreamsBuilder;
   8
   9 import java.util.Properties;
  10
  11
  12 @Slf4j
  13 public class Top10StreamProcessor
  14 {
  15         public final KafkaStreams streams;
  16
  17
  18         public Top10StreamProcessor(
  19                         String inputTopic,
  20                         String outputTopic,
  21                         ObjectMapper mapper,
  22                         Properties props)
  23         {
  24                 StreamsBuilder builder = new StreamsBuilder();
  25
  26                 builder
  27                                 .<Word, WordCount>stream(inputTopic)
  28                                 .map((word, wordCount) ->
  29                                 {
  30                                         Entry entry = Entry.of(word.getWord(), wordCount.getCount());
  31                                         return new KeyValue<>(word.getUser(), entry);
  32                                 })
  33                                 .groupByKey()
  34                                 .aggregate(
  35                                                 () -> new Ranking(),
  36                                                 (user, entry, ranking) ->
  37                                                 {
  38                                                         ranking.add(entry);
  39                                                         return ranking;
  40                                                 }
  41                                 )
  42                                 .toStream()
  43                                 .to(outputTopic);
  44
  45                 streams = new KafkaStreams(builder.build(), props);
  46         }
  47
  48         public void start()
  49         {
  50                 log.info("Starting Stream-Processor");
  51                 streams.start();
  52         }
  53
  54         public void stop()
  55         {
  56                 log.info("Stopping Stream-Processor");
  57                 streams.close();
  58         }
  59 }