examples/src/main/java/org/apache/falcon/example/spark/SparkWordCount.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.falcon.example.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;

/**
 * Spark Word Count example.
 */
public final class SparkWordCount {

    private SparkWordCount() {
    }
    protected static final FlatMapFunction<String, String> WORDS_EXTRACTOR =
            new FlatMapFunction<String, String>() {
                public Iterable<String> call(String s) throws Exception {
                    return Arrays.asList(s.split(" "));
                }
            };

    protected static final PairFunction<String, String, Integer> WORDS_MAPPER =
            new PairFunction<String, String, Integer>() {
                public Tuple2<String, Integer> call(String s) throws Exception {
                    return new Tuple2<String, Integer>(s, 1);
                }
            };

    protected static final Function2<Integer, Integer, Integer> WORDS_REDUCER =
            new Function2<Integer, Integer, Integer>() {
                public Integer call(Integer a, Integer b) throws Exception {
                    return a + b;
                }
            };

    public static void main(String[] args) {
        if (args.length < 1) {
            System.err.println("Please provide the input file full path as argument");
            System.exit(0);
        }

        SparkConf conf = new SparkConf().setAppName("Java WordCount");
        JavaSparkContext context = new JavaSparkContext(conf);
        JavaRDD<String> file = context.textFile(args[0]);
        JavaRDD<String> words = file.flatMap(WORDS_EXTRACTOR);
        JavaPairRDD<String, Integer> pairs = words.mapToPair(WORDS_MAPPER);
        JavaPairRDD<String, Integer> counter = pairs.reduceByKey(WORDS_REDUCER);
        counter.saveAsTextFile(args[1]);
    }
}