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.Arrays;
  import java.util.Iterator;
  import java.util.regex.Pattern;
  
  import scala.Tuple2;
  
  import org.apache.spark.SparkConf;
  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 org.apache.spark.api.java.StorageLevels;
  import org.apache.spark.streaming.Durations;
  import org.apache.spark.streaming.api.java.JavaDStream;
  import org.apache.spark.streaming.api.java.JavaPairDStream;
  import org.apache.spark.streaming.api.java.JavaReceiverInputDStream;
  import org.apache.spark.streaming.api.java.JavaStreamingContext;
  
  /**
   * Counts words in UTF8 encoded, '\n' delimited text received from the network every second.
   *
   * Usage: JavaNetworkWordCount <hostname> <port>
   * <hostname> and <port> describe the TCP server that Spark Streaming would connect to receive data.
   *
   * To run this on your local machine, you need to first run a Netcat server
   *    `$ nc -lk 9999`
   * and then run the example
   *    `$ bin/run-example org.apache.spark.examples.streaming.JavaNetworkWordCount localhost 9999`
   */
  public final class JavaNetworkWordCount {
    private static final Pattern SPACE = Pattern.compile(" ");
  
    public static void main(String[] args) throws Exception {
      if (args.length < 2) {
        System.err.println("Usage: JavaNetworkWordCount <hostname> <port>");
        System.exit(1);
      }
  
      StreamingExamples.setStreamingLogLevels();
  
      // Create the context with a 1 second batch size
      SparkConf sparkConf = new SparkConf().setAppName("JavaNetworkWordCount");
      JavaStreamingContext ssc = new JavaStreamingContext(sparkConf, Durations.seconds(1));
  
      // Create a JavaReceiverInputDStream on target ip:port and count the
      // words in input stream of \n delimited text (eg. generated by 'nc')
      // Note that no duplication in storage level only for running locally.
      // Replication necessary in distributed scenario for fault tolerance.
      JavaReceiverInputDStream<String> lines = ssc.socketTextStream(
              args[0], Integer.parseInt(args[1]), StorageLevels.MEMORY_AND_DISK_SER);
      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();
      ssc.start();
      ssc.awaitTermination();
    }
  }
  