Spark核心编程之二次排序

java 版本
自定义secondarySortKey

/**
 * 自定义的二次排序key
 * @author Administrator
 *
 */
public class SecondarySortKey implements Ordered<SecondarySortKey>, Serializable {
    private static final long serialVersionUID = -2366006422945129991L;
    // 首先在自定义key里面，定义需要进行排序的列
    private int first;
    private int second;
    public SecondarySortKey(int first, int second) {
        this.first = first;
        this.second = second;
    }
    @Override
    public boolean $greater(SecondarySortKey other) {
        if(this.first > other.getFirst()) {
            return true;
        } else if(this.first == other.getFirst() && 
                this.second > other.getSecond()) {
            return true;
        }
        return false;
    }
    @Override
    public boolean $greater$eq(SecondarySortKey other) {
        if(this.$greater(other)) {
            return true;
        } else if(this.first == other.getFirst() && 
                this.second == other.getSecond()) {
            return true;
        }
        return false;
    }
    @Override
    public boolean $less(SecondarySortKey other) {
        if(this.first < other.getFirst()) {
            return true;
        } else if(this.first == other.getFirst() && 
                this.second < other.getSecond()) {
            return true;
        }
        return false;
    }
    @Override
    public boolean $less$eq(SecondarySortKey other) {
        if(this.$less(other)) {
            return true;
        } else if(this.first == other.getFirst() && 
                this.second == other.getSecond()) {
            return true;
        }
        return false;
    }
    @Override
    public int compare(SecondarySortKey other) {
        if(this.first - other.getFirst() != 0) {
            return this.first - other.getFirst();
        } else {
            return this.second - other.getSecond();
        }
    }
    @Override
    public int compareTo(SecondarySortKey other) {
        if(this.first - other.getFirst() != 0) {
            return this.first - other.getFirst();
        } else {
            return this.second - other.getSecond();
        }
    }
    // 为要进行排序的多个列，提供getter和setter方法，以及hashcode和equals方法
    public int getFirst() {
        return first;
    }
    public void setFirst(int first) {
        this.first = first;
    }
    public int getSecond() {
        return second;
    }
    public void setSecond(int second) {
        this.second = second;
    }
    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + first;
        result = prime * result + second;
        return result;
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        SecondarySortKey other = (SecondarySortKey) obj;
        if (first != other.first)
            return false;
        if (second != other.second)
            return false;
        return true;
    }

应用程序

/**
 * 二次排序
 * 1、实现自定义的key，要实现Ordered接口和Serializable接口，在key中实现自己对多个列的排序算法
 * 2、将包含文本的RDD，映射成key为自定义key，value为文本的JavaPairRDD
 * 3、使用sortByKey算子按照自定义的key进行排序
 * 4、再次映射，剔除自定义的key，只保留文本行
 * @author Administrator
 *
 */
public class SecondarySort {
    public static void main(String[] args) {
        SparkConf conf = new SparkConf()
                .setAppName("SecondarySort") 
                .setMaster("local");
        JavaSparkContext sc = new JavaSparkContext(conf);
        JavaRDD<String> lines = sc.textFile("C://Users//Administrator//Desktop//sort.txt");
        JavaPairRDD<SecondarySortKey, String> pairs = lines.mapToPair(
                new PairFunction<String, SecondarySortKey, String>() {
                    private static final long serialVersionUID = 1L;
                    @Override
                    public Tuple2<SecondarySortKey, String> call(String line) throws Exception {
                        String[] lineSplited = line.split(" ");  
                        SecondarySortKey key = new SecondarySortKey(
                                Integer.valueOf(lineSplited[0]), 
                                Integer.valueOf(lineSplited[1]));  
                        return new Tuple2<SecondarySortKey, String>(key, line);
                    }
                });
        JavaPairRDD<SecondarySortKey, String> sortedPairs = pairs.sortByKey();
        JavaRDD<String> sortedLines = sortedPairs.map(
                new Function<Tuple2<SecondarySortKey,String>, String>() {
                    private static final long serialVersionUID = 1L;
                    @Override
                    public String call(Tuple2<SecondarySortKey, String> v1) throws Exception {
                        return v1._2;
                    }
                });
        sortedLines.foreach(new VoidFunction<String>() {
            private static final long serialVersionUID = 1L;
            @Override
            public void call(String t) throws Exception {
                System.out.println(t);  
            }
        });
        sc.close();
    }

scala 版
secondarykey

class SecondSortKey(val first: Int, val second: Int) 
    extends Ordered[SecondSortKey] with Serializable {
  def compare(that: SecondSortKey): Int = {
    if(this.first - that.first != 0) {
      this.first - that.first
    } else {
      this.second - that.second
    }
  }

应用程序

  def main(args: Array[String]): Unit = {
    val conf = new SparkConf()
        .setAppName("SecondSort")  
        .setMaster("local")  
    val sc = new SparkContext(conf)
    val lines = sc.textFile("C://Users//Administrator//Desktop//sort.txt", 1)
    val pairs = lines.map { line => (
        new SecondSortKey(line.split(" ")(0).toInt, line.split(" ")(1).toInt),
        line)}
    val sortedPairs = pairs.sortByKey()
    val sortedLines = sortedPairs.map(sortedPair => sortedPair._2)  
    sortedLines.foreach { sortedLine => println(sortedLine) }  
  }