kafka复习：（25）kafka stream

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 source = builder.stream("streams-plaintext-input");

        KTable 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