Spark scala和java的api使用 - HelloWorld开发者社区

1、利用scala语言开发spark的worcount程序（本地运行）

package com.zy.spark

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

//todo:利用scala语言来实现spark的wordcount程序
object WordCount {
  def main(args: Array[String]): Unit = {
    //1、创建SparkConf对象,设置appName和master  local[2]表示本地采用2个线程去运行任务
    val sparkConf: SparkConf = new SparkConf().setAppName("WordCount").setMaster("local[2]")

    //2、创建SparkContext 该对象是所有spark程序的执行入口，它会创建DAGScheduler和TaskScheduler
    val sc = new SparkContext(sparkConf)

    //设置日志输出级别
    sc.setLogLevel("warn")

    //3、读取数据文件
    val data: RDD[String] = sc.textFile("D:\\words.txt")

    //4、切分每一行获取所有单词
    val words: RDD[String] = data.flatMap(_.split(" "))

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

    //6、相同单词出现的所有的1累加
    val result: RDD[(String, Int)] = wordAndOne.reduceByKey(_ + _)

    //按照单词出现的次数降序排列
    val sortRDD: RDD[(String, Int)] = result.sortBy(x => x._2, false)


    //7、收集数据，打印输出
    val finalResult: Array[(String, Int)] = sortRDD.collect()
    finalResult.foreach(println)

    //8、关闭sc
    sc.stop()
  }
}

2、利用scala语言开发spark的wordcount程序（集群运行）

package com.zy.spark

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

//todo:利用scala语言开发spark的wordcount程序（集群运行）
object WordCount_Online {
  def main(args: Array[String]): Unit = {
    //1、创建SparkConf对象,设置appName
    val sparkConf: SparkConf = new SparkConf().setAppName("WordCount_Online")

    //2、创建SparkContext 该对象是所有spark程序的执行入口，它会创建DAGScheduler和TaskScheduler
    val sc = new SparkContext(sparkConf)

    //设置日志输出级别
    sc.setLogLevel("warn")

    //3、读取数据文件 args(0)为文件地址参数
    val data: RDD[String] = sc.textFile(args(0))

    //4、切分每一行获取所有单词
    val words: RDD[String] = data.flatMap(_.split(" "))

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

    //6、相同单词出现的所有的1累加
    val result: RDD[(String, Int)] = wordAndOne.reduceByKey(_ + _)

    //7、把结果数据保存到hdfs上  args(1)是保存到hdfs的目录参数
    result.saveAsTextFile(args(1))

    //8、关闭sc
    sc.stop()
  }

}

最后打成jar包到集群上执行

spark-submit --master spark://node1:7077 --class cn.itcast.spark.WordCount_Online --executor-memory 1g --total-executor-cores 2 original-spark_xxx-1.0-SNAPSHOT.jar /words.txt /out

3、利用java语言开发spark的wordcount程序（本地运行）

package com.zy.spark;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.FlatMapFunction;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.api.java.function.PairFunction;
import scala.Tuple2;

import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

//todo:利用java语言开发spark的wordcount程序（本地运行）
public class WordCount_Java {
    public static void main(String[] args) {
        //1、创建SparkConf对象
        SparkConf sparkConf = new SparkConf().setAppName("WordCount_Java").setMaster("local[2]");

        //2、创建JavaSparkContext对象
        JavaSparkContext jsc = new JavaSparkContext(sparkConf);

        //3、读取数据文件
        JavaRDD<String> data = jsc.textFile("D:\\words.txt");

        //4、切分每一行获取所有的单词
        JavaRDD<String> words = data.flatMap(new FlatMapFunction<String, String>() {
            public Iterator<String> call(String line) throws Exception {
                String[] words = line.split(" ");
                return Arrays.asList(words).iterator();
            }
        });

        //5、每个单词计为1
        JavaPairRDD<String, Integer> wordAndOne = words.mapToPair(new PairFunction<String, String, Integer>() {
            public Tuple2<String, Integer> call(String word) throws Exception {
                return new Tuple2<String, Integer>(word, 1);
            }
        });

        //6、相同单词出现1累加
        JavaPairRDD<String, Integer> result = wordAndOne.reduceByKey(new Function2<Integer, Integer, Integer>() {
            public Integer call(Integer v1, Integer v2) throws Exception {
                return v1 + v2;
            }
        });

        //按照单词出现的次数降序排列 (单词，次数)------>(次数，单词).sortByKey------->(单词，次数)

        JavaPairRDD<Integer, String> reverseRDD = result.mapToPair(new PairFunction<Tuple2<String, Integer>, Integer, String>() {
            public Tuple2<Integer, String> call(Tuple2<String, Integer> t) throws Exception {
                return new Tuple2<Integer, String>(t._2, t._1);
            }
        });

        JavaPairRDD<String, Integer> sortedRDD = reverseRDD.sortByKey(false).mapToPair(new PairFunction<Tuple2<Integer, String>, String, Integer>() {
            public Tuple2<String, Integer> call(Tuple2<Integer, String> t) throws Exception {
                return new Tuple2<String, Integer>(t._2, t._1);
            }
        });


        //7、收集数据打印输出
        List<Tuple2<String, Integer>> finalResult = sortedRDD.collect();
        for (Tuple2<String, Integer> tuple : finalResult) {
            System.out.println("单词：" + tuple._1 + " 次数：" + tuple._2);
        }

        //8、关闭jsc
        jsc.stop();
    }
}

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