kafka:如何消费、操作、确认(手动)并将结果发送到新主题

eiee3dmh  于 2021-06-07  发布在  Kafka
关注(0)|答案(2)|浏览(249)

我现在正在使用Kafka流图书馆。
我要做的是:(使用kafka流)我试图从主题中消费,操纵消息值,确认消息并将结果传输到另一个主题(下面的代码)

Properties properties = new Properties();
.
.
properties.put("enable.auto.commit", false);

StreamBuilder builder = new StreamBuilder();
KStream kStream = builder.stream("MyTopic");
KafkaStream kafkaStream = new KafkaStream(builder.build(), properties)

KafkaProducer<String, String> producer = new KafkaProducer<>(properties);

kStream.forEach(new ForeachAction<String, String>(){

 @Override
 public void apply(Strings arg, String value){
  //Just doing some simple data manipulation
  String myValue = value + new Date().toString();

  //Sending result to new topic
  producer.send(new ProducerRecord<String,String>("MyTopicWithTimeStamp", myValue)):
  // Problem (1) Here -> How do I acknowledge this from here manually

  // Problem (2) How should I properly handle/close my producer (if at all)
 }
});

kafkaStram.start();

我不知道怎么做:确认消息正确使用Kafka流库

46scxncf

46scxncf1#

代替使用手动方法,您可以直接通过kafka流api编写@amethystic。

source.mapValues(record -> record + new Date().toString()).to("MyTopicWithTimeStamp", 
    Produced.with(Serdes.String(), Serdes.String()));

关于acknowlegdement,您可以在stream configuration中设置属性,以确保producer在发布到主题时接收到确认。

final Properties props = new Properties();
props .put(StreamsConfig.producerPrefix(ProducerConfig.ACKS_CONFIG), "all");

您可以参考流配置:https://kafka.apache.org/21/documentation/streams/developer-guide/config-streams.html#acks

erhoui1w

erhoui1w2#

您可以使用kstream#直接写入kafka输出主题,而不是创建和维护自己的producer示例,如下所示:

final Properties props = new Properties();
...
final StreamsBuilder builder = new StreamsBuilder();
final KStream<String, String> source = builder.stream("MyTopic");
source.mapValues(record -> record + new Date().toString()).to("MyTopicWithTimeStamp", 
    Produced.with(Serdes.String(), Serdes.String()));
...
final KafkaStreams streams = new KafkaStreams(builder.build(), props);
streams.start();

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