我很新兴,并且我正在尝试从kafka主题接收结构化为json的DStream,并且我想解析每个json的内容。我收到的json是这样的:
{"type":"position","ident":"IBE32JZ","air_ground":"A","alt":"34000","clock":"1409733420","id":"IBE32JZ-1409715361-ed-0002:0","gs":"446","heading":"71","lat":"44.50987","lon":"2.98972","reg":"ECJRE","squawk":"1004","updateType":"A","altChange":" "}
我正在尝试仅提取ident字段,至少现在我正在使用lift-json库来解析de数据。我的程序看起来像这样:
object ScalaExample {
val kafkaHost = "localhost"
val kafkaPort = 9092
val zookeeperHost = "localhost"
val zookeeperPort = 2181
implicit val formats = DefaultFormats
case class PlaneInfo(ident: String)
def parser(json: String): String = {
val parsedJson = parse(json)
val m = paso1.extract[PlaneInfo]
return m.ident
}
def main(args : Array[String]) {
val zkQuorum = "localhost:2181"
val group = "myGroup"
val topic = Map("flightStatus" -> 1)
val sparkContext = new SparkContext("local[4]", "KafkaConsumer")
val ssc = new StreamingContext(sparkContext, Seconds(10))
val json = KafkaUtils.createStream(ssc, zkQuorum, group, topic)
val id = json.map(_._2).map(parser)
id.print
ssc.start()
}
}
但它引发了我下面的例外情况:
java.lang.NoClassDefFoundError: scala/reflect/ClassManifest
at net.liftweb.json.JsonAST$JValue.extract(JsonAST.scala:300)
at aero.catec.stratio.ScalaExample$.parser(ScalaExample.scala:33)
at aero.catec.stratio.ScalaExample$$anonfun$2.apply(ScalaExample.scala:48)
at aero.catec.stratio.ScalaExample$$anonfun$2.apply(ScalaExample.scala:48)
at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
at scala.collection.Iterator$$anon$10.next(Iterator.scala:312)
at scala.collection.Iterator$class.foreach(Iterator.scala:727)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48)
at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:103)
at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:47)
at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:273)
at scala.collection.AbstractIterator.to(Iterator.scala:1157)
at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:265)
at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1157)
at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:252)
at scala.collection.AbstractIterator.toArray(Iterator.scala:1157)
at org.apache.spark.rdd.RDD$$anonfun$28.apply(RDD.scala:1003)
at org.apache.spark.rdd.RDD$$anonfun$28.apply(RDD.scala:1003)
at org.apache.spark.SparkContext$$anonfun$runJob$4.apply(SparkContext.scala:1083)
at org.apache.spark.SparkContext$$anonfun$runJob$4.apply(SparkContext.scala:1083)
at org.apache.spark.scheduler.DAGScheduler.runLocallyWithinThread(DAGScheduler.scala:575)
at org.apache.spark.scheduler.DAGScheduler$$anon$1.run(DAGScheduler.scala:560)
Caused by: java.lang.ClassNotFoundException: scala.reflect.ClassManifest
at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
问题是,如果在不使用spark(从文件中读取)的情况下运行相同,它就能完美运行。当我尝试将它放入火花程序时,问题就出现了。另外,如果我将解析器函数更改为以下内容:
def parser(json: String): JValue = {
val parsedJson = parse(json)
return (parsedJson \\ "ident")
}
它也有效。但是当我尝试提取实际的String时,我得到了同样的错误。
感谢您的帮助。我希望我已经解释得很好。
答案 0 :(得分:2)
这是因为您缺少序列化/反序列化记录所需的scala反射依赖性。 尝试添加与spark版本匹配的scala反射jar。
提示: “org.scala-lang”%“scala-reflect”%Version.scala
答案 1 :(得分:0)
哦,一个很老的问题: - )
基本上这表示版本问题:您的一个依赖项与您当前使用的Scala编译器不兼容。你在2.10吗?
尝试使用Google搜索短语" NoClassDefFoundError:scala / reflect / ClassManifest" ,我相信您会找到关于该问题的足够描述。