Question

正如我使用url创建简单的kafka消费者：https://gist.github.com/akhil/6dfda8a04e33eff91a20。

在该链接中，要打印已消费的记录，请使用单词＆＃34; asScala＆＃34; ，那是没有确定的。并且，请告诉我，如何迭代返回类型：ConsumerRecord [String，String]，这是poll（）方法的返回类型。

＆＃13;

import java.util
import java.util.Properties

import org.apache.kafka.clients.consumer.{ConsumerRecords, KafkaConsumer}

 
object KafkaConsumerEx extends App {

  val topic_name = "newtopic55"
  val consumer_group = "KafkaConsumerBatch"

  val prot = new Properties()
  prot.put("bootstrap.servers","localhost:9092")
  prot.put("group.id",consumer_group)
  prot.put("key.deserializer",  "org.apache.kafka.common.serialization.StringDeserializer")
  prot.put("value.deserializer","org.apache.kafka.common.serialization.StringDeserializer")

  val kfk_consumer = new KafkaConsumer[String,String](prot)
  kfk_consumer.subscribe(util.Collections.singleton(topic_name))
  println("here")

   while(true){
    val consumer_record : ConsumerRecords[String, String]  = kfk_consumer.poll(100)
    println("records count : " + consumer_record.count())
    println("records partitions: " + consumer_record.partitions())
    consumer_record.iterator().


  }

}

＆＃13;

先谢谢。

Answer 1

你可以轻松地做到这一点

for (record <- consumer_record.iterator()) {
  println(s"Here's your $record")
}

请记住添加此导入：

import scala.collection.JavaConversions._

Answer 2

添加另一个答案，因为scala.collection.JavaConversions已被弃用，如here所述。

对于这个问题，代码可能像

import scala.collection.JavaConverters._

for (record <- asScalaIterator(consumer_record.iterator)) {
  println(s"Here's your $record")
}

Answer 3

while(true){
    val consumer_records = kfk_consumer.poll(100)
    val record_iter=consumer_record.iterator()
    while(record_iter.hasNext())
    {
       record=record_iter.next()
       println("records partitions: " + record.partition()
               "records_data:" + record.value())
    }
}

Kafka scala消费者代码 - 打印消费记录

3 个答案: