Spark-Java-算子

package scala.spark.Day3;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.api.java.function.VoidFunction;

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

/**
 * Created by Administrator on 2019/10/16.
 */
public class JavaRDDTest {
    public static void main(String[] args) {
        System.setProperty("hadoop.home.dir", "E:\hadoop-2.6.0-cdh5.15.0\hadoop-2.6.0-cdh5.15.0");

        //JavaRDD  标准RDD
        //JavaPairRDD PairRDD
        //JavaDoubleRDD DoubleRDD
        //java没有scala隐式转化，生成RDD时候，必须指明是哪种RDD

        //实例化驱动器
        SparkConf sparkConf = new SparkConf();
        sparkConf.setMaster("local");
        sparkConf.setAppName("Java RDD");

        JavaSparkContext javaSparkContext = new JavaSparkContext(sparkConf);

        //javaSparkContext.parallelize()     标准RDD
        //javaSparkContext.parallelizePairs()      PairRDD
        //javaSparkContext.parallelizeDoubles()    数值类型RDD

        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);

        JavaRDD<Integer> sourceRDD = javaSparkContext.parallelize(list);

        //map 算子
        // 匿名子类
        /*
        public interface Function<T1, R> extends Serializable {
            R call(T1 v1) throws Exception;
        }

        T1  RDD中成员的类型
        v1  返回的类型
         */

        JavaRDD<Integer> mapRDD = sourceRDD.map(
                new Function<Integer, Integer>() {

                    public Integer call(Integer v1) throws Exception {
                        return v1 * v1;
                    }
                }
        );

        /*
        public interface VoidFunction<T> extends Serializable {
             void call(T t) throws Exception;
        }
         */
        mapRDD.foreach(
                new VoidFunction<Integer>() {
                    public void call(Integer integer) throws Exception {
                        System.out.println(integer);
                    }
                }
        );


        javaSparkContext.close();


    }
}