juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java

   1 package de.juplo.kafka.wordcount.counter;
   2
   3 import com.fasterxml.jackson.databind.ObjectMapper;
   4 import lombok.extern.slf4j.Slf4j;
   5 import org.apache.kafka.common.serialization.Serdes;
   6 import org.apache.kafka.streams.KafkaStreams;
   7 import org.apache.kafka.streams.KeyValue;
   8 import org.apache.kafka.streams.StreamsBuilder;
   9 import org.apache.kafka.streams.Topology;
  10 import org.apache.kafka.streams.kstream.KStream;
  11 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
  12 import org.apache.kafka.streams.kstream.*;
  13
  14 import java.util.Properties;
  15
  16
  17 @Slf4j
  18 public class CounterStreamProcessor
  19 {
  20         public final KafkaStreams streams;
  21
  22
  23         public CounterStreamProcessor(
  24                         String inputTopic,
  25                         String outputTopic,
  26                         Properties properties,
  27                         KeyValueBytesStoreSupplier storeSupplier,
  28                         ObjectMapper mapper)
  29         {
  30                 Topology topology = CounterStreamProcessor.buildTopology(
  31                                 inputTopic,
  32                                 outputTopic,
  33                                 storeSupplier,
  34                                 mapper);
  35
  36                 streams = new KafkaStreams(topology, properties);
  37         }
  38
  39         static Topology buildTopology(
  40                         String inputTopic,
  41                         String outputTopic,
  42                         KeyValueBytesStoreSupplier storeSupplier,
  43                         ObjectMapper mapper)
  44         {
  45                 StreamsBuilder builder = new StreamsBuilder();
  46
  47                 KStream<String, Word> source = builder.stream(
  48                                 inputTopic,
  49                                 Consumed.with(Serdes.String(), null));
  50
  51                 source
  52                                 .map((key, word) -> new KeyValue<>(word, word))
  53                                 .groupByKey()
  54                                 .count(Materialized.as(storeSupplier))
  55                                 .toStream()
  56                                 .map((word, count) -> new KeyValue<>(word, WordCount.of(word, count)))
  57                                 .to(outputTopic);
  58
  59                 Topology topology = builder.build();
  60                 log.info("\n\n{}", topology.describe());
  61
  62                 return topology;
  63         }
  64
  65         public void start()
  66         {
  67                 log.info("Starting Stream-Processor");
  68                 streams.start();
  69         }
  70
  71         public void stop()
  72         {
  73                 log.info("Stopping Stream-Processor");
  74                 streams.close();
  75         }
  76 }