Question

我正在编写一个代码，我试图使用kafka和spark来消费消息。但我的代码不起作用。这是我的代码：

import org.apache.kafka.clients.producer.{ KafkaProducer, ProducerConfig, ProducerRecord }
import org.apache.spark.streaming._
import org.apache.spark.SparkConf
import org.apache.spark.rdd.RDD
import org.apache.spark.sql.SparkSession
import java.util._

object Smack_Kafka_Spark extends App {
def main(args: Array[String]) {
val kafkaBrokers = "localhost:2181"

val kafkaOpTopic = "test"
/*val props = new HashMap[String, Object]()
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaBrokers)
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,
  "org.apache.kafka.common.serialization.StringSerializer")
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG,
  "org.apache.kafka.common.serialization.StringSerializer")*/

val props = new Properties()
props.put("bootstrap.servers", "localhost:2181")

props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer")
props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer")

val producer = new KafkaProducer[String, String](props)

var spark: SparkSession = null
val textFile: RDD[String] = spark.sparkContext.textFile("dataset.txt")
textFile.foreach(record => {
  val data = record.toString
  val message = new ProducerRecord[String, String](kafkaOpTopic, null, data)
  producer.send(message)
})
 producer.close()
 }
}

这是我得到的错误：

log4j:WARN No appenders could be found for logger (org.apache.kafka.clients.producer.ProducerConfig).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Exception in thread "main" java.lang.NullPointerException
at Smack_Kafka_Spark$.main(Smack_Kafka_Spark.scala:25)
at Smack_Kafka_Spark.main(Smack_Kafka_Spark.scala)

我将非常感谢任何帮助！

Answer 1

您收到NullPointerException因为SparkSession为空。像下面这样创建它。

val spark : SparkSession = SparkSession.builder()
  .appName("Smack_Kafka_Spark")
  .master("local[*]")
  .getOrCreate()

现在阅读下面的文本文件。

val textFile: Dataset[String] = spark.read.textFile("dataset.txt")

运行程序时可能遇到的另一个问题是

Exception in thread "main" org.apache.spark.SparkException: Task not serializable
Caused by: java.io.NotSerializableException: org.apache.kafka.clients.producer.KafkaProducer

KafkaProducer不可轻易化。您需要在foreachPartition中移动KafkaProducer实例。请查看SO帖子spark kafka producer serializable

找不到logger的追加程序（org.apache.kafka.clients.producer.ProducerConfig）

1 个答案: