-package de.juplo.kafka.wordcount.counter;
-
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.clients.consumer.ConsumerConfig;
-import org.apache.kafka.common.serialization.Serdes;
-import org.apache.kafka.streams.KafkaStreams;
-import org.apache.kafka.streams.KeyValue;
-import org.apache.kafka.streams.StreamsBuilder;
-import org.apache.kafka.streams.StreamsConfig;
-import org.apache.kafka.streams.kstream.KStream;
-import org.springframework.boot.SpringApplication;
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.stereotype.Component;
-
-import javax.annotation.PostConstruct;
-import javax.annotation.PreDestroy;
-import java.util.Arrays;
-import java.util.Properties;
-import java.util.concurrent.CompletableFuture;
-import java.util.regex.Pattern;
-
-import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
-
-
-@Slf4j
-@Component
-public class CounterStreamProcessor
-{
- final static Pattern PATTERN = Pattern.compile("\\W+");
-
- public final KafkaStreams streams;
-
-
- public CounterStreamProcessor(
- CounterApplicationProperties properties,
- ObjectMapper mapper,
- ConfigurableApplicationContext context)
- {
- StreamsBuilder builder = new StreamsBuilder();
-
- KStream<String, String> source = builder.stream(properties.getInputTopic());
- source
- .flatMapValues(sentence -> Arrays.asList(PATTERN.split(sentence)))
- .map((username, word) ->
- {
- try
- {
- String key = mapper.writeValueAsString(Key.of(username, word));
- return new KeyValue<>(key, word);
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
- })
- .groupByKey()
- .count()
- .mapValues(value->Long.toString(value))
- .toStream()
- .to(properties.getOutputTopic());
-
- Properties props = new Properties();
- props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
- props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
- props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
- props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
- props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
-
- streams = new KafkaStreams(builder.build(), props);
- streams.setUncaughtExceptionHandler((Throwable e) ->
- {
- log.error("Unexpected error!", e);
- CompletableFuture.runAsync(() ->
- {
- log.info("Stopping application...");
- SpringApplication.exit(context, () -> 1);
- });
- return SHUTDOWN_CLIENT;
- });
- }
-
- @PostConstruct
- public void start()
- {
- log.info("Starting Stream-Processor");
- streams.start();
- }
-
- @PreDestroy
- public void stop()
- {
- log.info("Stopping Stream-Processor");
- streams.close();
- }
-}