org.apache.spark.SparkException: A master URL must be set in your configuration

 

org.apache.spark.SparkException: A master URL must be set in your configuration

错误

org.apache.spark.SparkException: A master URL must be set in your configuration
	at org.apache.spark.SparkContext.(SparkContext.scala:379) ~[spark-core_2.11-2.1.4-SNAPSHOT.jar:2.1.4-SNAPSHOT]
	at org.apache.spark.SparkContext$.getOrCreate(SparkContext.scala:2323) [spark-core_2.11-2.1.4-SNAPSHOT.jar:2.1.4-SNAPSHOT]
	at org.apache.spark.sql.SparkSession$Builder$$anonfun$6.apply(SparkSession.scala:876) [spark-sql_2.11-2.1.4-SNAPSHOT.jar:2.1.4-SNAPSHOT]
	at org.apache.spark.sql.SparkSession$Builder$$anonfun$6.apply(SparkSession.scala:868) [spark-sql_2.11-2.1.4-SNAPSHOT.jar:2.1.4-SNAPSHOT]
	at scala.Option.getOrElse(Option.scala:121) [scala-library-2.11.8.jar:na]
	at org.apache.spark.sql.SparkSession$Builder.getOrCreate(SparkSession.scala:868) [spark-sql_2.11-2.1.4-SNAPSHOT.jar:2.1.4-SNAPSHOT]
	at org.apache.spark.examples.sql.JavaSparkSQLExample.main(JavaSparkSQLExample.java:96) [classes/:na]

从提示中可以看出找不到程序运行的master，此时需要配置环境变量。 
传递给spark的master url可以有如下几种： 
local 本地单线程 
local[K] 本地多线程（指定K个内核） 
local[*] 本地多线程（指定所有可用内核） 
spark://HOST:PORT 连接到指定的 Spark standalone cluster master，需要指定端口。 
mesos://HOST:PORT 连接到指定的 Mesos 集群，需要指定端口。 
yarn-client客户端模式 连接到 YARN 集群。需要配置 HADOOP_CONF_DIR。 
yarn-cluster集群模式 连接到 YARN 集群。需要配置 HADOOP_CONF_DIR。 

项目右击--> Run As --> Run Configurations --> arguments --> VM arguments 设置为“-Dspark.master=local”