nl.utwente.bigdata.MessageCount.java Source code

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Here is the source code for nl.utwente.bigdata.MessageCount.java

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/**
 * 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 nl.utwente.bigdata;

import java.io.IOException;
import java.util.StringTokenizer;
import java.util.Map;
import java.util.ArrayList;
import java.util.Iterator;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import org.json.simple.parser.JSONParser;
import org.json.simple.JSONObject;

public class MessageCount {

    public static class CountMapper2 extends Mapper<Object, Text, Text, IntWritable> {

        private Text dateString = new Text();
        private JSONParser parser = new JSONParser();
        private Map tweet;
        private String createdAt = new String();
        private String createYear = new String();
        private String createMonth = new String();
        private String createDay = new String();
        private final static IntWritable one = new IntWritable(1);

        public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
            try {
                tweet = (Map<String, Object>) parser.parse(value.toString());

                createdAt = (String) tweet.get("created_at");
                if (createdAt != null) {
                    createYear = createdAt.substring(createdAt.lastIndexOf(" ") + 1);
                    createMonth = createdAt.split("\\s+")[1];
                    createDay = createdAt.split("\\s+")[2];

                    dateString.set(createYear.concat(createMonth.concat(createDay)));
                    context.write(dateString, one);
                }
            } catch (ClassCastException e) {
                return; // do nothing (we might log this)
            } catch (org.json.simple.parser.ParseException e) {
                return; // do nothing 
            }
        }
    }

    public static class IntSumReducer2 extends Reducer<Text, IntWritable, Text, IntWritable> {
        private IntWritable result = new IntWritable();

        public void reduce(Text key, Iterable<IntWritable> values, Context context)
                throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable val : values) {
                sum += val.get();
            }
            result.set(sum);
            context.write(key, result);
        }
    }

    public static void main(String[] args) throws Exception {
        Configuration conf = new Configuration();
        Job job = Job.getInstance(conf, "count message per day");

        job.setJarByClass(MessageCount.class);
        job.setMapperClass(CountMapper2.class);
        job.setReducerClass(IntSumReducer2.class);
        job.setCombinerClass(IntSumReducer2.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(IntWritable.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(IntWritable.class);
        FileInputFormat.addInputPath(job, new Path(args[0]));
        FileOutputFormat.setOutputPath(job, new Path(args[1]));
        System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}