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.core.JsonProcessingException;
   4 import com.fasterxml.jackson.databind.ObjectMapper;
   5 import lombok.extern.slf4j.Slf4j;
   6 import org.apache.kafka.clients.consumer.ConsumerConfig;
   7 import org.apache.kafka.common.serialization.Serdes;
   8 import org.apache.kafka.streams.KafkaStreams;
   9 import org.apache.kafka.streams.KeyValue;
  10 import org.apache.kafka.streams.StreamsBuilder;
  11 import org.apache.kafka.streams.StreamsConfig;
  12 import org.apache.kafka.streams.kstream.KStream;
  13 import org.springframework.boot.SpringApplication;
  14 import org.springframework.context.ConfigurableApplicationContext;
  15 import org.springframework.stereotype.Component;
  16
  17 import javax.annotation.PostConstruct;
  18 import javax.annotation.PreDestroy;
  19 import java.util.Arrays;
  20 import java.util.Properties;
  21 import java.util.concurrent.CompletableFuture;
  22 import java.util.regex.Pattern;
  23
  24 import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
  25
  26
  27 @Slf4j
  28 @Component
  29 public class CounterStreamProcessor
  30 {
  31         final static Pattern PATTERN = Pattern.compile("\\W+");
  32
  33         public final KafkaStreams streams;
  34
  35
  36         public CounterStreamProcessor(
  37                         CounterApplicationProperties properties,
  38                         ObjectMapper mapper,
  39                         ConfigurableApplicationContext context)
  40         {
  41                 StreamsBuilder builder = new StreamsBuilder();
  42
  43                 KStream<String, String> source = builder.stream(properties.getInputTopic());
  44                 source
  45                                 .flatMapValues(sentence -> Arrays.asList(PATTERN.split(sentence)))
  46                                 .map((username, word) ->
  47                                 {
  48                                         try
  49                                         {
  50                                                 String key = mapper.writeValueAsString(Key.of(username, word));
  51                                                 return new KeyValue<>(key, word);
  52                                         }
  53                                         catch (JsonProcessingException e)
  54                                         {
  55                                                 throw new RuntimeException(e);
  56                                         }
  57                                 })
  58                                 .groupByKey()
  59                                 .count()
  60                                 .mapValues(value->Long.toString(value))
  61                                 .toStream()
  62                                 .to(properties.getOutputTopic());
  63
  64                 Properties props = new Properties();
  65                 props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
  66                 props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
  67                 props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  68                 props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  69                 props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
  70
  71                 streams = new KafkaStreams(builder.build(), props);
  72                 streams.setUncaughtExceptionHandler((Throwable e) ->
  73                 {
  74                         log.error("Unexpected error!", e);
  75                         CompletableFuture.runAsync(() ->
  76                         {
  77                                 log.info("Stopping application...");
  78                                 SpringApplication.exit(context, () -> 1);
  79                         });
  80                         return SHUTDOWN_CLIENT;
  81                 });
  82         }
  83
  84         @PostConstruct
  85         public void start()
  86         {
  87                 log.info("Starting Stream-Processor");
  88                 streams.start();
  89         }
  90
  91         @PreDestroy
  92         public void stop()
  93         {
  94                 log.info("Stopping Stream-Processor");
  95                 streams.close();
  96         }
  97 }