collectAsMap : 针对K,V格式的RDD进行操作，将K,V格式的RDD回收到Driver端形成一个Map

  1. scala
package action

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

/**
 * @Author yqq
 * @Date 2021/12/10 11:52
 * @Version 1.0
 */
object CollectAsMapTest1 {
  def main(args: Array[String]): Unit = {
    val context = new SparkContext(
      new SparkConf()
        .setMaster("local")
        .setAppName("CollectAsMapTest")
    )
    context.setLogLevel("Error")
    context.parallelize(Array[(String,Int)](
      ("科比",24),
      ("科比",8),
      ("詹姆斯",23),
      ("詹姆斯",6),
      ("乔丹",23)
    )).collectAsMap().foreach(println)
  }
}

Spark Action算子-＞collectAsMap_scala
2. java

package action;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaSparkContext;
import scala.Tuple2;

import java.util.Arrays;
import java.util.Map;
import java.util.Set;

/**
 * @Author yqq
 * @Date 2021/12/10 11:41
 * @Version 1.0
 */
public class CollectAsMapTest {
    public static void main(String[] args) {
        JavaSparkContext context = new JavaSparkContext(
                new SparkConf()
                        .setMaster("local")
                        .setAppName("CollectAsMapTest")
        );
        context.setLogLevel("Error");
        Map<String, Integer> map = context.parallelizePairs(Arrays.asList(
                new Tuple2<>("科比", 24),
                new Tuple2<>("科比", 8),
                new Tuple2<>("詹姆斯", 23),
                new Tuple2<>("詹姆斯", 6),
                new Tuple2<>("乔丹", 23)
        )).collectAsMap();
        Set<Map.Entry<String,Integer>> set = map.entrySet();
        set.forEach(e->{
            String key = e.getKey();
            Integer value = e.getValue();
            System.out.println("key=:"+key+",value=:"+value);
        });
    }
}

Spark Action算子-＞collectAsMap_spark_02