package de.juplo.kafka.wordcount.top10;
-import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.streams.KafkaStreams;
StreamsBuilder builder = new StreamsBuilder();
builder
- .<String, String>stream(inputTopic)
- .map((keyJson, countStr) ->
+ .<Word, WordCount>stream(inputTopic)
+ .map((word, wordCount) ->
{
- try
- {
- Key key = mapper.readValue(keyJson, Key.class);
- Long count = Long.parseLong(countStr);
- Entry entry = Entry.of(key.getWord(), count);
- String entryJson = mapper.writeValueAsString(entry);
- return new KeyValue<>(key.getUsername(), entryJson);
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
+ Entry entry = Entry.of(word.getWord(), wordCount.getCount());
+ return new KeyValue<>(word.getUser(), entry);
})
.groupByKey()
.aggregate(
- () -> "{\"entries\" : []}",
- (username, entryJson, rankingJson) ->
+ () -> new Ranking(),
+ (user, entry, ranking) ->
{
- try
- {
- Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
- ranking.add(mapper.readValue(entryJson, Entry.class));
- return mapper.writeValueAsString(ranking);
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
+ ranking.add(entry);
+ return ranking;
}
)
.toStream()