本文基于文章 https://blog.csdn.net/lemonlhy/article/details/80059289，感激原作者，再次我又对 spark 罕用的 rdd java 接口用 lambda 表达式从新实现了一遍，代码更简洁。
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package org.apache.kylin.spark;
import org.apache.spark.Partitioner;
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.Function;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.api.java.function.PairFunction;
import org.apache.spark.api.java.function.VoidFunction;
import scala.Tuple2;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.stream.StreamSupport;
/**
*/
public class TransformationOperator {public static SparkConf conf = new SparkConf().setMaster("local").setAppName("test");
public static JavaSparkContext sc = new JavaSparkContext(conf);
public static void main(String[] args) {//map();
//filter();
//flatMap();
//groupBykey();
//reduceBykey();
// sortBykey();
//join();
//union();
// intersection();
// cartesian();
// distinct();
//mapPartitions();
// repartition();
//coalesce();
//aggregateByKey();
//mapPartitionsWithIndex();
cogroup();
// repartitionAndSortWithinPartitions();
// sample();}
public static void map(){final List<String> list = Arrays.asList("张无忌", "赵敏", "周芷若");
/*final Set<String> set = Sets.newLinkedHashSet();
set.addAll(list);*/
final JavaRDD<String> rdd = sc.parallelize(list);
System.out.println("\nLambda 表达式实现：");
rdd.map(name -> "Hello" + name).foreach(s -> println(s));
}
public static void flatMap() {final List<String> list = Arrays.asList("张无忌 赵敏", "宋青书 周芷若");
final JavaRDD<String> rdd = sc.parallelize(list);
System.out.println("\nLambda 表达式实现：");
rdd.flatMap(names -> Arrays.asList(names.split(" ")).iterator())
.map(name -> "Hello" + name)
.foreach(name -> println(name));
}
/**
* 从 RDD 过滤出来偶数
*/
public static void filter(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7);
final JavaRDD<Integer> rdd = sc.parallelize(list);
System.out.println("\nLambda 表达式实现：");
rdd.filter(x -> x%2 == 0).foreach(x -> println(String.valueOf(x)));
}
/**RDD()
* bykey
*/
public static void groupBykey(){
final List<Tuple2<String, String>> list = Arrays.asList(new Tuple2<String, String>("峨眉", "周芷若"),
new Tuple2<String, String>("武当", "宋青书"),
new Tuple2<String, String>("峨眉", "灭绝师太"),
new Tuple2<String, String>("武当", "张三丰")
);
final JavaPairRDD<String, String> rdd = (JavaPairRDD<String, String>)sc.parallelizePairs(list);
final JavaPairRDD<String, Iterable<String>> groupBykeyRDD = rdd.groupByKey();
System.out.println("\nLambda 表达式实现 1：");
groupBykeyRDD.foreach(names -> {println(names._1);
Iterator<String> iterator = names._2.iterator();
while (iterator.hasNext()) {System.out.print(iterator.next() + " ");
}
System.out.println();});
System.out.println("\nLambda 表达式实现 1：");
groupBykeyRDD.foreach(names -> {println(names._1);
names._2.forEach(name -> System.out.print(name + " "));
System.out.println();});
}
/**
* 一线城市：8 年 -> 100 万
* 5: 50 以上 IT
*/
public static void reduceBykey(){
final List<Tuple2<String, Integer>> list = Arrays.asList(new Tuple2<String, Integer>("峨眉", 40),
new Tuple2<String, Integer>("武当", 30),
new Tuple2<String, Integer>("峨眉",60),
new Tuple2<String, Integer>("武当",99)
);
//reduceBykey
final JavaPairRDD<String, Integer> rdd = (JavaPairRDD<String, Integer>)sc.parallelizePairs(list);
System.out.println("\nLambda 表达式实现：");
rdd.reduceByKey((x, y) -> x + y).foreach(tuple -> println(tuple._1 + " " + tuple._2));
}
public static void sortBykey(){
final List<Tuple2<Integer, String>> list = Arrays.asList(new Tuple2<Integer, String>(98,"东方不败"),
new Tuple2<Integer, String>(80,"岳不群"),
new Tuple2<Integer, String>(85,"令狐冲"),
new Tuple2<Integer, String>(83,"任我行")
);
final JavaPairRDD<Integer, String> rdd = (JavaPairRDD<Integer, String>)sc.parallelizePairs(list);
System.out.println("\nLambda 表达式实现：");
rdd.sortByKey(false).foreach(tuple -> println(tuple._1 + "->" + tuple._2));
}
public static void join(){
final List<Tuple2<Integer, String>> names = Arrays.asList(new Tuple2<Integer, String>(1, "东方不败"),
new Tuple2<Integer, String>(2, "令狐冲"),
new Tuple2<Integer, String>(3, "林平之")
);
final List<Tuple2<Integer, Integer>> scores = Arrays.asList(new Tuple2<Integer, Integer>(1, 99),
new Tuple2<Integer, Integer>(2, 98),
new Tuple2<Integer, Integer>(3, 97)
);
final JavaPairRDD<Integer, String> nemesrdd = (JavaPairRDD<Integer, String>)sc.parallelizePairs(names);
final JavaPairRDD<Integer, Integer> scoresrdd = (JavaPairRDD<Integer, Integer>)sc.parallelizePairs(scores);
/**
* <Integer, 学号
* Tuple2<String, 名字
* Integer>> 分数
*/
System.out.println("\nLambda 表达式实现：");
sc.parallelizePairs(names).join(sc.parallelizePairs(scores)).sortByKey()
.foreach(tuple -> println("学号：" + tuple._1 + "名字：" + tuple._2._1 + "分数：" + tuple._2._2));
}
public static void union(){final List<Integer> list1 = Arrays.asList(1, 2, 3, 4);
final List<Integer> list2 = Arrays.asList(3, 4, 5, 6);
final JavaRDD<Integer> rdd1 = sc.parallelize(list1);
final JavaRDD<Integer> rdd2 = sc.parallelize(list2);
System.out.println("\nLambda 表达式实现：");
rdd1.union(rdd2).foreach(value -> System.out.print(value + " "));
}
/**
* 交加
*/
public static void intersection(){final List<Integer> list1 = Arrays.asList(1, 2, 3, 4);
final List<Integer> list2 = Arrays.asList(3, 4, 5, 6);
final JavaRDD<Integer> rdd1 = sc.parallelize(list1);
final JavaRDD<Integer> rdd2 = sc.parallelize(list2);
System.out.println("\nLambda 表达式实现：");
rdd1.intersection(rdd2).foreach(number -> System.out.print(number + " "));
}
public static void distinct() {final List<Integer> list1 = Arrays.asList(1, 2, 3,3,4,4);
final JavaRDD<Integer> rdd1 = sc.parallelize(list1);
System.out.println("\nLambda 表达式实现：");
rdd1.distinct().sortBy(value-> value, true, 1).foreach(value -> println(value + " "));
}
/**
* 笛卡尔积
* A={a,b}
* B={0,1,2}
* A B 笛卡尔积
* a0,a1,a2
* b0,b1,b2
*/
public static void cartesian(){final List<String> A = Arrays.asList("a", "b");
final List<Integer> B = Arrays.asList(0, 1, 2);
final JavaRDD<String> rddA = sc.parallelize(A);
final JavaRDD<Integer> rddB = sc.parallelize(B);
System.out.println("\nLambda 表达式实现：");
rddA.cartesian(rddB).foreach(tuple -> println(tuple._1 + "->" + tuple._2));
}
/**
* map:
* 一条数据一条数据的解决（文件系统，数据库等等）* mapPartitions：* 一次获取的是一个分区的数据（hdfs）* 失常状况下，mapPartitions 是一个高性能的算子
* 因为每次解决的是一个分区的数据，缩小了去获取数据的次数。*
* 然而如果咱们的分区如果设置得不合理，有可能导致每个分区外面的数据量过大。*/
public static void mapPartitions(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6);
// 参数二代表这个 rdd 外面有两个分区
final JavaRDD<Integer> rdd = sc.parallelize(list, 2);
System.out.println("\nLambda 表达式实现：");
rdd.mapPartitions(integerIterator -> {Iterable<Integer> integers = () -> integerIterator;
return StreamSupport.stream(integers.spliterator(),true)
.map(value -> "hello-" + value).iterator();}).foreach(value -> println(value));
}
/**
* 进行重分区
* HDFS -》hello.txt 2 个文件块（不蕴含正本）* 2 个文件块 -》2 个分区 -》当 spark 工作运行，一个分区就启动一个 task 工作。*
* 解决的问题：原本分区数少 -》减少分区数
*/
public static void repartition(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6);
final JavaRDD<Integer> rdd = (JavaRDD<Integer>) sc.parallelize(list, 1);
// coalesce(numPartitions, shuffle = true)
System.out.println("\nLambda 表达式实现：");
rdd.repartition(2).foreach(number -> println(number + ""));
}
/**
* 实现单词计数
*/
public static void aggregateByKey(){final List<String> list = Arrays.asList("you,jump", "i,jump");
final JavaRDD<String> rdd = sc.parallelize(list);
System.out.println("\nLambda 表达式实现：");
rdd.flatMap(lines -> Arrays.asList(lines.split(",")).iterator())
.mapToPair(word -> new Tuple2<>(word, 1))
.aggregateByKey(0, (v1, v2) -> v1 + v2, (v1, v2) -> v1 + v2)
.foreach(v -> println(v._1 + "->" + v._2));
}
/**
* 分区数由多 -> 变少
*/
public static void coalesce(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6);
final JavaRDD<Integer> rdd = (JavaRDD<Integer>) sc.parallelize(list, 3);
System.out.println("\nLambda 表达式实现：");
rdd.coalesce(1).foreach(v -> println(v + ""));
}
/**
* map: 每次获取和解决的就是一条数据
* mapParitions: 每次获取和解决的就是一个分区的数据
* mapPartitionsWithIndex: 每次获取和解决的就是一个分区的数据, 并且晓得解决的分区的分区号是啥？*/
public static void mapPartitionsWithIndex(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8);
final JavaRDD<Integer> rdd = sc.parallelize(list, 2);//HashParitioners Rangepartitionw 自定义分区
System.out.println("\nLambda 表达式实现：");
rdd.mapPartitionsWithIndex((integer, iterator) -> {Iterable integers = () -> iterator;
return StreamSupport.stream(integers.spliterator(), true)
.map(value -> integer + "_" + value).iterator();}, true)
.foreach(value -> println(value + ""));
}
/**
* When called on datasets of type (K, V) and (K, W),
* returns a dataset of (K, (Iterable<V>, Iterable<W>)) tuples.
*/
public static void cogroup(){
//sh s sha shan shang sa san sang
final List<Tuple2<Integer, String>> list1 = Arrays.asList(new Tuple2<Integer, String>(1, "东方不败"),
new Tuple2<Integer, String>(2, "林平之"),
new Tuple2<Integer, String>(3, "岳不群"),
new Tuple2<Integer, String>(1, "东方不败"),
new Tuple2<Integer, String>(2, "林平之"),
new Tuple2<Integer, String>(3, "岳不群")
);
final List<Tuple2<Integer, Integer>> list2 = Arrays.asList(new Tuple2<Integer, Integer>(1, 90),
new Tuple2<Integer, Integer>(2, 91),
new Tuple2<Integer, Integer>(3, 89),
new Tuple2<Integer, Integer>(1, 98),
new Tuple2<Integer, Integer>(2, 78),
new Tuple2<Integer, Integer>(3, 67)
);
final JavaPairRDD<Integer, String> rdd1 = (JavaPairRDD<Integer, String>)sc.parallelizePairs(list1);
final JavaPairRDD<Integer, Integer> rdd2 = (JavaPairRDD<Integer, Integer>)sc.parallelizePairs(list2);
final JavaPairRDD<Integer, Tuple2<Iterable<String>, Iterable<Integer>>> rdd3 =
(JavaPairRDD<Integer, Tuple2<Iterable<String>, Iterable<Integer>>>) rdd1.cogroup(rdd2);
rdd3.foreach(new VoidFunction<Tuple2<Integer, Tuple2<Iterable<String>, Iterable<Integer>>>>() {
@Override
public void call(Tuple2<Integer, Tuple2<Iterable<String>, Iterable<Integer>>> tuple) throws Exception {
final Integer id = tuple._1;
final Iterable<String> names = tuple._2._1;
final Iterable<Integer> scores = tuple._2._2;
println("ID:"+id + "Name:"+names+ "Scores:"+ scores);
}
});
}
/**
* 少 -> 多
*
*/
public static void repartitionAndSortWithinPartitions(){// 调优
final List<Integer> list = Arrays.asList(1, 2, 11, 3, 12, 4, 5);
final JavaRDD<Integer> rdd = sc.parallelize(list, 1);
final JavaPairRDD<Integer, Integer> pairRDD = rdd.mapToPair(new PairFunction<Integer, Integer, Integer>() {
@Override
public Tuple2<Integer, Integer> call(Integer number) throws Exception {return new Tuple2<>(number, number);
}
});
//new HashPartitioner(2) new RangePartitioner<>()
pairRDD.repartitionAndSortWithinPartitions(new Partitioner() {
@Override
public int numPartitions() {return 2;}
@Override
public int getPartition(Object key) {final Integer number = Integer.valueOf(key.toString());
if(number % 2 == 0){return 0;}else{return 1;}
}
}).mapPartitionsWithIndex(new Function2<Integer, Iterator<Tuple2<Integer, Integer>>,
Iterator<String>>() {
@Override
public Iterator<String> call(Integer index, Iterator<Tuple2<Integer, Integer>> iterator) throws Exception {final ArrayList<String> list = new ArrayList<>();
while(iterator.hasNext()){list.add(index + "_"+ iterator.next());
}
return list.iterator();}
},false)
.foreach(new VoidFunction<String>() {
@Override
public void call(String s) throws Exception {println(s);
}
});
}
/**
* 有放回
* 无放回
*/
public static void sample(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7,9,10);
final JavaRDD<Integer> rdd = sc.parallelize(list);
/**
* withReplacement: Boolean,
* true: 有放回的抽样
* false: 无放回形象
* fraction: Double：* RDD 外面的每个元素被抽到的概率有多大
* seed: Long：* 随机种子
*
*
*/
final JavaRDD<Integer> rdd2 = rdd.sample(false, 0.5);
rdd2.foreach(new VoidFunction<Integer>() {
@Override
public void call(Integer integer) throws Exception {println(integer + "");
}
});
}
public static void pipe(){final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7,9,10);
final JavaRDD<Integer> rdd = sc.parallelize(list);
// final JavaRDD<String> pipe = rdd.pipe("sh wordcouont.sh");
}
public static void println(String str){System.out.println(str);
}
}