-
Notifications
You must be signed in to change notification settings - Fork 262
WordCount version one
Dennis Dawson edited this page Aug 28, 2015
·
11 revisions
package org.myorg;
import java.io.IOException;
import java.util.regex.Pattern;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.log4j.Logger;
public class WordCount extends Configured implements Tool {
private static final Logger LOG = Logger.getLogger(WordCount.class);
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new WordCount(), args);
System.exit(res);
}
public int run(String[] args) throws Exception {
Job job = Job.getInstance(getConf(), "wordcount");
job.setJarByClass(this.getClass());
// Use TextInputFormat, the default unless job.setInputFormatClass is used
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
return job.waitForCompletion(true) ? 0 : 1;
}
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
private long numRecords = 0;
private static final Pattern WORD_BOUNDARY = Pattern.compile("\\s*\\b\\s*");
public void map(LongWritable offset, Text lineText, Context context)
throws IOException, InterruptedException {
String line = lineText.toString();
Text currentWord = new Text();
for (String word : WORD_BOUNDARY.split(line)) {
if (word.isEmpty()) {
continue;
}
currentWord = new Text(word);
context.write(currentWord,one);
}
}
}
public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> {
@Override
public void reduce(Text word, Iterable<IntWritable> counts, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable count : counts) {
sum += count.get();
}
context.write(word, new IntWritable(sum));
}
}
}