我运行了下面的代码，与您的代码类似，它对我有效：

import models.Info
import org.apache.spark.rdd.RDD
import play.api.libs.json.Json
import domain.utils.Implicits._

class CustomFunctions(rdd : RDD[Info]) {
  def save() = {
    rdd.map(i => Json.toJson(i).toString ).saveAsTextFile("/home/training/so-123")
  }

}

写了相应的 Implicits :

package domain.utils

import play.api.libs.json.{JsObject, Json, Writes}
import models.Info

class Implicits {
  implicit val InfoWrites = new Writes[Info]{
    def writes(i : Info): JsObject = Json.obj(
      "key1" -> i.key1,
      "key2" -> i.key2,
      "key3" -> i.key3
    )
  }

}

object Implicits extends  Implicits

创建了模型 Info :

package models

case class Info(key1 : String, key2 : String, key3 : String)

创建了一个 SparkOperationsDao 要编写和创建spark上下文：

package dao

import domain.utils.CustomFunctions
import models.Info
import org.apache.spark.{SparkConf, SparkContext}

class SparkOperationsDao {
  val conf:SparkConf = new SparkConf().setAppName("driverTrack").setMaster("local")
  val sc = new SparkContext(conf)

  def writeToElastic() = {
    val sample = List(Info("name1", "city1", "123"), Info("name2", "city2", "234"))
    val rdd = sc.parallelize(sample)
    val converter = new CustomFunctions(rdd)
    converter.save()
  }

}

object SparkOperationsDao extends SparkOperationsDao

运行应用程序：

import dao.SparkOperationsDao

object RapidTests extends App {
  SparkOperationsDao.writeToElastic()
    //.collect.foreach(println)

}