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.streaming.examples;
  
  import java.util.Map;
  import java.util.HashMap;
  import java.util.regex.Pattern;
  
  import com.google.common.collect.Lists;
  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.streaming.Duration;
  import org.apache.spark.streaming.api.java.JavaDStream;
  import org.apache.spark.streaming.api.java.JavaPairDStream;
  import org.apache.spark.streaming.api.java.JavaStreamingContext;
  import org.apache.spark.streaming.kafka.KafkaUtils;
  import scala.Tuple2;
  
  /**
   * Consumes messages from one or more topics in Kafka and does wordcount.
   * Usage: JavaKafkaWordCount <master> <zkQuorum> <group> <topics> <numThreads>
   *   <master> is the Spark master URL. In local mode, <master> should be 'local[n]' with n > 1.
   *   <zkQuorum> is a list of one or more zookeeper servers that make quorum
   *   <group> is the name of kafka consumer group
   *   <topics> is a list of one or more kafka topics to consume from
   *   <numThreads> is the number of threads the kafka consumer should use
   *
   * Example:
   *    `./bin/run-example org.apache.spark.streaming.examples.JavaKafkaWordCount local[2] zoo01,zoo02,
   *    zoo03 my-consumer-group topic1,topic2 1`
   */
  
  public final class JavaKafkaWordCount {
    private static final Pattern SPACE = Pattern.compile(" ");
  
    private JavaKafkaWordCount() {
    }
  
    public static void main(String[] args) {
      if (args.length < 5) {
        System.err.println("Usage: KafkaWordCount <master> <zkQuorum> <group> <topics> <numThreads>");
        System.exit(1);
      }
  
      StreamingExamples.setStreamingLogLevels();
  
      // Create the context with a 1 second batch size
      JavaStreamingContext jssc = new JavaStreamingContext(args[0], "KafkaWordCount",
              new Duration(2000), System.getenv("SPARK_HOME"),
              JavaStreamingContext.jarOfClass(JavaKafkaWordCount.class));
  
      int numThreads = Integer.parseInt(args[4]);
      Map<String, Integer> topicMap = new HashMap<String, Integer>();
      String[] topics = args[3].split(",");
      for (String topic: topics) {
        topicMap.put(topic, numThreads);
      }
  
      JavaPairDStream<String, String> messages = KafkaUtils.createStream(jssc, args[1], args[2], topicMap);
  
      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 Iterable<String> call(String x) {
          return Lists.newArrayList(SPACE.split(x));
        }
      });
  
      JavaPairDStream<String, Integer> wordCounts = words.mapToPair(
        new PairFunction<String, String, Integer>() {
          @Override
          public Tuple2<String, Integer> call(String s) {
            return new Tuple2<String, Integer>(s, 1);
          }
        }).reduceByKey(new Function2<Integer, Integer, Integer>() {
          @Override
          public Integer call(Integer i1, Integer i2) {
            return i1 + i2;
          }
        });
  
      wordCounts.print();
      jssc.start();
      jssc.awaitTermination();
    }
  }
  