一、java代码：

package com.cisdi.dsp.modules.metaAnalysis.rest.kafka2023;import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.*;import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;public class KafkaTest25 {public static void main(String[] args) throws Exception {Properties props = new Properties();props.put(StreamsConfig.APPLICATION_ID_CONFIG, "streams-wordcount");props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "k8s-master:9092");props.put(StreamsConfig.CACHE_MAX_BYTES_BUFFERING_CONFIG, 0);props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());StreamsBuilder builder = new StreamsBuilder();KStream<String, String> source = builder.stream("streams-plaintext-input");KTable<String, Long> counts = source.flatMapValues(value -> Arrays.asList(value.toLowerCase().split(" "))).groupBy((key, value) -> value).count();counts.toStream().to("streams-wordcount-output", Produced.with(Serdes.String(), Serdes.Long()));final KafkaStreams streams = new KafkaStreams(builder.build(), props);final CountDownLatch latch = new CountDownLatch(1);Runtime.getRuntime().addShutdownHook(new Thread("streams-wordcount-shutdown-hook") {public void run() {streams.close();latch.countDown();}});try {streams.start();latch.await();} catch (Throwable e) {System.exit(1);}System.exit(0);}
}

二、启动console producer:

bin/kafka-console-producer.sh --broker-list xx.xx.xx.xx:9092 --topic streams-plaintext-input

三、启动console consumer:

./kafka-console-consumer.sh --bootstrap-server xx.xx.xx.xx:9092 \--topic streams-wordcount-output \--from-beginning \--formatter kafka.tools.DefaultMessageFormatter \--property print.key=true \--property print.value=true \--property key.deserializer=org.apache.kafka.common.serialization.StringDeserializer \--property value.deserializer=org.apache.kafka.common.serialization.LongDeserializer

四、在producer端输入字符串（空格分割），看consumer输出