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 lombok.extern.slf4j.Slf4j;
   4 import org.apache.kafka.streams.*;
   5 import org.apache.kafka.streams.kstream.KStream;
   6 import org.apache.kafka.streams.kstream.Materialized;
   7 import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
   8 import org.apache.kafka.streams.state.QueryableStoreTypes;
   9 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  10
  11 import java.util.Properties;
  12
  13
  14 @Slf4j
  15 public class CounterStreamProcessor
  16 {
  17         public static final String STORE_NAME = "counter";
  18
  19
  20         public final KafkaStreams streams;
  21
  22
  23         public CounterStreamProcessor(
  24                         String inputTopic,
  25                         String outputTopic,
  26                         Properties properties,
  27                         KeyValueBytesStoreSupplier storeSupplier)
  28         {
  29                 Topology topology = CounterStreamProcessor.buildTopology(
  30                                 inputTopic,
  31                                 outputTopic,
  32                                 storeSupplier);
  33
  34                 streams = new KafkaStreams(topology, properties);
  35         }
  36
  37         static Topology buildTopology(
  38                         String inputTopic,
  39                         String outputTopic,
  40                         KeyValueBytesStoreSupplier storeSupplier)
  41         {
  42                 StreamsBuilder builder = new StreamsBuilder();
  43
  44                 KStream<User, Word> source = builder.stream(inputTopic);
  45
  46                 source
  47                                 .map((key, word) -> new KeyValue<>(word, word))
  48                                 .groupByKey()
  49                                 .count(Materialized.as(storeSupplier))
  50                                 .toStream()
  51                                 .map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
  52                                 .to(outputTopic);
  53
  54                 Topology topology = builder.build();
  55                 log.info("\n\n{}", topology.describe());
  56
  57                 return topology;
  58         }
  59
  60         ReadOnlyKeyValueStore<Word, Long> getStore()
  61         {
  62                 return streams.store(StoreQueryParameters.fromNameAndType(STORE_NAME, QueryableStoreTypes.keyValueStore()));
  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 }