"main"线程中的异常：java.lang.NoClassDefFoundError: org/apache/spark/streaming/StreamingContext。

Question

看起来在以下代码中找不到StreamingContext类。

import org.apache.spark.streaming.{Seconds, StreamingContext}
import org.apache.spark.{SparkConf, SparkContext}
object Exemple {
  def main(args: Array[String]): Unit = {
    val conf = new SparkConf().setMaster("local[*]").setAppName("Exemple")
    val sc = new SparkContext(conf)
    val ssc = new StreamingContext(sc, Seconds(2)) //this line throws error

  }
}

这里是错误：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/spark/streaming/StreamingContext
    at Exemple$.main(Exemple.scala:16)
    at Exemple.main(Exemple.scala)
Caused by: java.lang.ClassNotFoundException: org.apache.spark.streaming.StreamingContext
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 2 more

Process finished with exit code 1

我使用以下的build.sbt文件：

name := "exemple"

version := "1.0.0"

scalaVersion := "2.11.11"

// https://mvnrepository.com/artifact/org.apache.spark/spark-sql
libraryDependencies += "org.apache.spark" %% "spark-sql" % "2.2.0"
// https://mvnrepository.com/artifact/org.apache.spark/spark-streaming
libraryDependencies += "org.apache.spark" %% "spark-streaming" % "2.2.0" % "provided"
// https://mvnrepository.com/artifact/org.apache.spark/spark-streaming-kafka-0-10
libraryDependencies += "org.apache.spark" %% "spark-streaming-kafka-0-10" % "2.2.0"

我使用Intellij的运行按钮运行Exemple类，但出现错误。在sbt shell中可以正常工作。在我的依赖模块中，我可以找到Spark依赖项。代码在Intellij中编译。我可以在外部库中看到Spark依赖项（在左侧项目面板中）。 你有什么想法。这似乎不复杂。

- a.moussa

Answer 1

请从spark-streaming库中删除provided条目。

libraryDependencies += "org.apache.spark" %% "spark-streaming" % "2.2.0" 

在更改后，仍然存在依赖问题，进一步排除重复的jar包。

 "org.apache.spark" %% "spark-streaming-kafka-0-10" % "2.2.0" excludeAll(
      ExclusionRule(organization = "org.spark-project.spark", name = "unused"),
      ExclusionRule(organization = "org.apache.spark", name = "spark-streaming"),
      ExclusionRule(organization = "org.apache.hadoop")
    ),

希望这有所帮助。

谢谢， Ravi

- Ravikumar

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非常感谢您。 - a.moussa