在IDEA中使用Scala语言编写WordCount程序

1.使用IDEA创建Maven项目

2.导入pom.xml文件

<properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <scala.version>2.11.8</scala.version>
        <spark.version>2.1.0</spark.version>
        <hadoop.version>2.6.0</hadoop.version>
        <encoding>UTF-8</encoding>
    </properties>

    <dependencies>
        <!-- 导入scala的依赖 -->
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>${scala.version}</version>
        </dependency>

        <!-- 导入spark的依赖 -->
        <dependency>
            <groupId>org.apache.spark</groupId>
            <artifactId>spark-core_2.11</artifactId>
            <version>${spark.version}</version>
        </dependency>

        <!-- 指定hadoop-client API的版本 -->
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>${hadoop.version}</version>
        </dependency>

    </dependencies>

    <build>
        <pluginManagement>
            <plugins>
                <!-- 编译scala的插件 -->
                <plugin>
                    <groupId>net.alchim31.maven</groupId>
                    <artifactId>scala-maven-plugin</artifactId>
                    <version>3.2.2</version>
                </plugin>
                <!-- 编译java的插件 -->
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.5.1</version>
                </plugin>
            </plugins>
        </pluginManagement>
        <plugins>
            <plugin>
                <groupId>net.alchim31.maven</groupId>
                <artifactId>scala-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <id>scala-compile-first</id>
                        <phase>process-resources</phase>
                        <goals>
                            <goal>add-source</goal>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>scala-test-compile</id>
                        <phase>process-test-resources</phase>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <executions>
                    <execution>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>


            <!-- 打jar插件 -->
            <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>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

注意：    这里的Scala  Spark  Hadoop版本必须按照集群上的修改，特别是Scala和Spark的，要和你集群上的版本号一致，可以在Spark集群中使用Spark Shell模式查看版本号

3.编写WordCount程序

package cn.ysjh0014

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

object ScalaWordCount {

  def main(args: Array[String]): Unit = {
    //创建Spark配置，应用程序的名字
    val conf = new SparkConf().setAppName("ScalaWordCount")
    //创建Spark程序执行的入口
    val sc = new SparkContext(conf)
    //指定以后从哪读取数据创建RDD(弹性分布式数据集)
    val line = sc.textFile(args(0))
    //切分压平
    val word = line.flatMap(_.split(" "))
    //将单词和1组成元组
    val WordOne = word.map((_, 1))
    //按照key进行聚合
    val reduce = WordOne.reduceByKey(_ + _)
    //排序
    val sort = reduce.sortBy(_._2, false)
    //将结果保存到hdfs
    sort.saveAsTextFile(args(1))
    //释放资源
    sc.stop()

  }
}

4.使用Maven打成jar包

在IDEA中view---->Tool Windows--->Maven Projects--->Package，jar包在target下，有两个jar包，original-Spark-1.0-SNAPSHOT.jar是只将代码打成了jar包，Spark-1.0-SNAPSHOT.jar是将所有依赖也打成了jar包

5.提交到Spark集群上测试

bin/spark-submit \
--master spark://cdh0:7077 \
--class cn.ysjh0014.ScalaWordCount \            包名+项目名
/opt/package/original-Spark-1.0-SNAPSHOT.jar \  jar包所在目录
hdfs://cdh0:8020/usr/ys/input/test.txt \        读取数据的hdfs路径
hdfs://cdh0:8020/usr/output                     保存数据到hdfs的路径

6.查看运行结果

至此运行成功