content: /*
   * 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.spark.examples.streaming;
  
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Arrays;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  import java.util.regex.Pattern;
  
  import scala.Tuple2;
  
  import kafka.serializer.StringDecoder;
  
  import org.apache.spark.SparkConf;
  import org.apache.spark.api.java.function.*;
  import org.apache.spark.streaming.api.java.*;
  import org.apache.spark.streaming.kafka.KafkaUtils;
  import org.apache.spark.streaming.Durations;
  
  /**
   * Consumes messages from one or more topics in Kafka and does wordcount.
   * Usage: JavaDirectKafkaWordCount <brokers> <topics>
   *   <brokers> is a list of one or more Kafka brokers
   *   <topics> is a list of one or more kafka topics to consume from
   *
   * Example:
   *    $ bin/run-example streaming.JavaDirectKafkaWordCount broker1-host:port,broker2-host:port \
   *      topic1,topic2
   */
  
  public final class JavaDirectKafkaWordCount {
    private static final Pattern SPACE = Pattern.compile(" ");
  
    public static void main(String[] args) throws Exception {
      if (args.length < 2) {
        System.err.println("Usage: JavaDirectKafkaWordCount <brokers> <topics>\n" +
            "  <brokers> is a list of one or more Kafka brokers\n" +
            "  <topics> is a list of one or more kafka topics to consume from\n\n");
        System.exit(1);
      }
  
      StreamingExamples.setStreamingLogLevels();
  
      String brokers = args[0];
      String topics = args[1];
  
      // Create context with a 2 seconds batch interval
      SparkConf sparkConf = new SparkConf().setAppName("JavaDirectKafkaWordCount");
      JavaStreamingContext jssc = new JavaStreamingContext(sparkConf, Durations.seconds(2));
  
      Set<String> topicsSet = new HashSet<>(Arrays.asList(topics.split(",")));
      Map<String, String> kafkaParams = new HashMap<>();
      kafkaParams.put("metadata.broker.list", brokers);
  
      // Create direct kafka stream with brokers and topics
      JavaPairInputDStream<String, String> messages = KafkaUtils.createDirectStream(
          jssc,
          String.class,
          String.class,
          StringDecoder.class,
          StringDecoder.class,
          kafkaParams,
          topicsSet
      );
  
      // Get the lines, split them into words, count the words and print
      JavaDStream<String> lines = messages.map(new Function<Tuple2<String, String>, String>() {
        @Override
        public String call(Tuple2<String, String> tuple2) {
          return tuple2._2();
        }
      });
      JavaDStream<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
        @Override
        public Iterator<String> call(String x) {
          return Arrays.asList(SPACE.split(x)).iterator();
        }
      });
      JavaPairDStream<String, Integer> wordCounts = words.mapToPair(
        new PairFunction<String, String, Integer>() {
          @Override
          public Tuple2<String, Integer> call(String s) {
            return new Tuple2<>(s, 1);
          }
        }).reduceByKey(
          new Function2<Integer, Integer, Integer>() {
          @Override
          public Integer call(Integer i1, Integer i2) {
            return i1 + i2;
          }
        });
      wordCounts.print();
  
      // Start the computation
      jssc.start();
      jssc.awaitTermination();
    }
  }
  