Created
July 9, 2017 18:33
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/* | |
* To change this license header, choose License Headers in Project Properties. | |
* To change this template file, choose Tools | Templates | |
* and open the template in the editor. | |
*/ | |
package wordcounthadoop; | |
import java.io.IOException; | |
import java.util.StringTokenizer; | |
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; | |
public class WordCount { | |
public static class TokenizerMapper | |
extends Mapper<Object, Text, Text, IntWritable>{ | |
private final static IntWritable ONE = new IntWritable(1); | |
private final Text word = new Text(); | |
/** | |
* | |
* @param key | |
* @param value | |
* @param context | |
* @throws IOException | |
* @throws InterruptedException | |
*/ | |
@Override | |
public void map(Object key, Text value, Context context | |
) throws IOException, InterruptedException { | |
StringTokenizer itr = new StringTokenizer(value.toString()); | |
while (itr.hasMoreTokens()) { | |
word.set(itr.nextToken()); | |
context.write(word, ONE); | |
} | |
} | |
} | |
public static class IntSumReducer | |
extends Reducer<Text,IntWritable,Text,IntWritable> { | |
private final IntWritable result = new IntWritable(); | |
@Override | |
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, "word count"); | |
job.setJarByClass(WordCount.class); | |
job.setMapperClass(TokenizerMapper.class); | |
job.setCombinerClass(IntSumReducer.class); | |
job.setReducerClass(IntSumReducer.class); | |
job.setOutputKeyClass(Text.class); | |
job.setOutputValueClass(IntWritable.class); | |
FileInputFormat.addInputPath(job, new Path(args[0])); | |
FileOutputFormat.setOutputPath(job, new Path(args[1])); | |
System.exit(job.waitForCompletion(true) ? 0 : 1); | |
} | |
} | |
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