cn.com.warlock.streaming.JavaDirectKafkaWordCount.java Source code

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Here is the source code for cn.com.warlock.streaming.JavaDirectKafkaWordCount.java

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/**
 * Copyright (C) 2015 Baifendian Corporation
 *
 * Licensed 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 cn.com.warlock.streaming;

import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.regex.Pattern;

import kafka.serializer.StringDecoder;

import org.apache.spark.SparkConf;
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.Durations;
import org.apache.spark.streaming.api.java.JavaDStream;
import org.apache.spark.streaming.api.java.JavaPairDStream;
import org.apache.spark.streaming.api.java.JavaPairInputDStream;
import org.apache.spark.streaming.api.java.JavaStreamingContext;
import org.apache.spark.streaming.kafka.KafkaUtils;

import scala.Tuple2;

import com.google.common.collect.Lists;

/**
 * kafka streaming ?
 * <p>
 * 
 * @author : dsfan
 * @date : 201641
 */
public final class JavaDirectKafkaWordCount {
    private static final Pattern SPACE = Pattern.compile(" ");

    public static void main(String[] args) {
        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);
        }

        String brokers = args[0];
        String topics = args[1];

        SparkConf sparkConf = new SparkConf().setAppName("JavaDirectKafkaWordCount");
        //  StreamingContext,?2?
        JavaStreamingContext jssc = new JavaStreamingContext(sparkConf, Durations.seconds(2));

        HashSet<String> topicsSet = new HashSet<String>(Arrays.asList(topics.split(",")));
        HashMap<String, String> kafkaParams = new HashMap<String, String>();
        kafkaParams.put("metadata.broker.list", brokers);
        kafkaParams.put("auto.offset.reset", "smallest");

        //  brokers  topics  direct kafka stream
        JavaPairInputDStream<String, String> messages = KafkaUtils.createDirectStream(jssc, String.class,
                String.class, StringDecoder.class, StringDecoder.class, kafkaParams, topicsSet);

        // ?
        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();

        // Start the computation
        jssc.start();
        jssc.awaitTermination();
    }
}