主程序代码如下:

import org.apache.spark.rdd.RDD
import org.apache.spark.{SparkConf, SparkContext}


//todo:利用scala语言开发spark的wordcount程序（本地运行）
object WordCount {
  def main(args: Array[String]): Unit = {
    //1、创建SparkConf对象 设置applicationName和master地址   local[2]表示本地采用2个线程
    val sparkConf: SparkConf = new SparkConf().setAppName("WordCount").setMaster("local[2]")

    //2、创建SparkContext对象,它是所有spark程序执行入口，它内部会构建DAGScheduler和TaskScheduler
    val sc = new SparkContext(sparkConf)
    //设置日志输出级别
    sc.setLogLevel("warn")

    //3、读取文件数据
    val data: RDD[String] = sc.textFile("E:\\words.txt")

    //4、切分每一行，获取所有的单词
    val words: RDD[String] = data.flatMap(x=>x.split(" "))

    //5、每个单词计为1
    val wordAndOne: RDD[(String, Int)] = words.map(x =>(x,1))

    //6、相同单词出现的1累加
    val result: RDD[(String, Int)] = wordAndOne.reduceByKey((x:Int,y:Int)=>x+y)

    //按照单词出现的次数降序排列  默认第二个参数是true，在这里表示升序，改为false就是降序
    val sortedRDD: RDD[(String, Int)] = result.sortBy(x => x._2,false)


    //7、收集数据打印
    val finalResult: Array[(String, Int)] = sortedRDD.collect
    finalResult.foreach(x=>println(x))

    //8、关闭sc
    sc.stop()
  }
}

pom.xml文件:

    <properties>
        <!--<scala.version>2.11.8</scala.version>-->
        <hadoop.version>3.1.0</hadoop.version>
        <!--<spark.version>2.1.3</spark.version>-->
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.12.7</version>
        </dependency>
        <dependency>
            <groupId>org.apache.spark</groupId>
            <artifactId>spark-core_2.12</artifactId>
            <version>2.4.0</version>
        </dependency>
    </dependencies>


    <build>
        <sourceDirectory>src/main/scala</sourceDirectory>
        <testSourceDirectory>src/test/scala</testSourceDirectory>
        <plugins>
            <plugin>
                    <groupId>net.alchim31.maven</groupId>
                    <artifactId>scala-maven-plugin</artifactId>
                    <version>3.2.2</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>testCompile</goal>
                        </goals>
                        <configuration>
                            <args>
                                <arg>-dependencyfile</arg>
                                <arg>${project.build.directory}/.scala_dependencies</arg>
                            </args>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>2.4.3</version>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <filters>
                                <filter>
                                    <artifact>*:*</artifact>
                                    <excludes>
                                        <exclude>META-INF/*.SF</exclude>
                                        <exclude>META-INF/*.DSA</exclude>
                                        <exclude>META-INF/*.RSA</exclude>
                                    </excludes>
                                </filter>
                            </filters>
                            <transformers>
                                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <mainClass></mainClass>
                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

程序启动后报错内容如下: