Kafka Streams :获取时间窗口中的事件计数

import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.TimeWindows;
import org.apache.kafka.streams.kstream.Windowed;

import java.util.Properties;

public class EventCountInTimeWindow {
    public static void main(String[] args) {
        // 配置Kafka Streams应用程序的属性
        Properties props = new Properties();
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "event-count-app");
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");

        // 创建流构建器
        StreamsBuilder builder = new StreamsBuilder();

        // 从输入主题中获取数据流
        KStream<String, String> inputStream = builder.stream("input-topic");

        // 定义时间窗口和聚合操作
        inputStream
                .groupByKey()
                .windowedBy(TimeWindows.of(5000)) // 5秒的时间窗口
                .count()
                .toStream()
                .foreach((Windowed<String> key, Long count) -> {
                    System.out.println("时间窗口：" + key.window().toString() + "，事件计数：" + count);
                });

        // 构建Kafka Streams应用程序并启动
        KafkaStreams streams = new KafkaStreams(builder.build(), props);
        streams.start();
    }
}