spark接收kafka数据，进行WordCount

package kafka

import org.apache.spark.SparkConf
import org.apache.spark.streaming.{Seconds, StreamingContext}
import org.apache.spark.streaming.kafka010._

import scala.collection.mutable

//1.打开zk,kafka。2.启动kafka-connect(source部分)3.运行此文件
object DirectKafka {
  def main(args: Array[String]): Unit = {
    if (args.length < 2) {
      System.err.println(
        s"""
           |Usage: DirectKafkaWordCount <brokers> <topics>
           |  <brokers> is a list of one or more Kafka brokers
           |  <topics> is a list of one or more kafka topics to consume from
           |
        """.stripMargin)
      System.exit(1)
    }
    val Array(brokers,topics)=args

    var conf = new SparkConf()
      .setAppName("DirectKafka")
      .setMaster("local[2]")

    val ssc = new StreamingContext(conf, Seconds(2))

    val topicsSet=topics.split(",").toSet
    val kafkaParams=mutable.HashMap[String,String]()
    //必须添加以下参数，否则会报错
    kafkaParams.put("bootstrap.servers" ,brokers)
    kafkaParams.put("group.id", "group1")
    kafkaParams.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")
    kafkaParams.put("value.deserializer" , "org.apache.kafka.common.serialization.StringDeserializer")
    val messages=KafkaUtils.createDirectStream [String,String](
      ssc,
      LocationStrategies.PreferConsistent,
      ConsumerStrategies.Subscribe[String,String](topicsSet,kafkaParams
      )
    )
    // Get the lines, split them into words, count the words and print
    val lines = messages.map(_.value)
    val words = lines.flatMap(_.split(" "))
    val wordCounts = words.map(x => (x, 1L)).reduceByKey(_ + _)
    wordCounts.print()

    // Start the computation
    ssc.start()
    ssc.awaitTermination()

  }
}

maven依赖一定要跟Scala版本一致，否则执行代码会报错：

<!-- https://mvnrepository.com/artifact/org.apache.spark/spark-streaming-kafka-0-10 -->
<dependency>
    <groupId>org.apache.spark</groupId>
    <artifactId>spark-streaming-kafka-0-10_2.12</artifactId>
    <version>2.4.0</version>
</dependency>