5.3 Kafka Streams API之算子演示

1.代码示例

public class StreamSample {
    private static final String TOPIC_INPUT = "steven-stream-in";

    private static final String TOPIC_OUT = "steven-stream-out";

    public static void main(String[] args) {
        //Stream配置
        Properties props = new Properties();
        props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "127.0.0.1:9092");
        props.put(StreamsConfig.APPLICATION_ID_CONFIG, "wordCount");
        props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
        props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass());

        //构建流结构拓扑
        final StreamsBuilder builder = new StreamsBuilder();
        //构建流计算过程
        foreachStream(builder);
        final KafkaStreams streams = new KafkaStreams(builder.build(), props);
        streams.start();
    }

    /**
     * 构建流计算过程
     *
     * @param builder
     */
    static void foreachStream(final StreamsBuilder builder) {
        KStream<String, String> source = builder.stream(TOPIC_INPUT);
        source.flatMapValues(value -> Arrays.asList(value.toLowerCase(Locale.getDefault()).split(" ")))
                .foreach((key, value) -> System.out.println(key + ":" + value));
    }
}

2.代码运行结果
(1).创建生产者
打开一个cmd终端，在E:\Kafka\kafka_2.12-1.1.0\bin\windows目录下执行kafka-console-producer.bat --broker-list localhost:9092 --topic steven-stream-in命令，创建生产者。

kafka-console-producer.bat --broker-list localhost:9092 --topic steven-stream-in

(2).创建消费者
打开一个cmd终端，在E:\Kafka\kafka_2.12-1.1.0\bin\windows目录下执行kafka-console-consumer.bat --zookeeper localhost:2181 --topic steven-stream-out命令，创建消费者。

kafka-console-consumer.bat --zookeeper localhost:2181 --topic steven-stream-out 
--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

(3).生产者命令框中输入数据

I am Chinese
I am American
I am from China

(4).控制台查看分析结果

null:I
null:am
null:Chinese
null:I
null:am
null:American
null:I
null:am
null:from
null:China