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WordCount application in Java 7, using Kafka's Streams API (Kafka version 0.11.0.0)
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import org.apache.kafka.common.serialization.Serdes; | |
import org.apache.kafka.streams.KafkaStreams; | |
import org.apache.kafka.streams.StreamsConfig; | |
import org.apache.kafka.streams.kstream.KStream; | |
import org.apache.kafka.streams.kstream.KStreamBuilder; | |
import org.apache.kafka.streams.kstream.KTable; | |
import org.apache.kafka.streams.kstream.KeyValueMapper; | |
import org.apache.kafka.streams.kstream.ValueMapper; | |
import java.util.Arrays; | |
import java.util.Properties; | |
import java.util.concurrent.TimeUnit; | |
public class WordCountApplication { | |
public static void main(final String[] args) throws Exception { | |
Properties config = new Properties(); | |
config.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordcount-application"); | |
config.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "kafka-broker1:9092"); | |
config.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass()); | |
config.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass()); | |
KStreamBuilder builder = new KStreamBuilder(); | |
KStream<String, String> textLines = builder.stream("TextLinesTopic"); | |
KTable<String, Long> wordCounts = textLines | |
.flatMapValues(new ValueMapper<String, Iterable<String>>() { | |
@Override | |
public Iterable<String> apply(String textLine) { | |
return Arrays.asList(textLine.toLowerCase().split("\\W+")); | |
} | |
}) | |
.groupBy(new KeyValueMapper<String, String, String>() { | |
@Override | |
public String apply(String key, String word) { | |
return word; | |
} | |
}) | |
.count("Counts"); | |
wordCounts.to(Serdes.String(), Serdes.Long(), "WordsWithCountsTopic"); | |
KafkaStreams streams = new KafkaStreams(builder, config); | |
streams.start(); | |
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() { | |
@Override | |
public void run() { | |
streams.close(10, TimeUnit.SECONDS); | |
} | |
})); | |
} | |
} |
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