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WordCount version one
"""package org.myorg;
import java.io.IOException; import java.util.StringTokenizer; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; 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.input.FileSplit; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; 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 by default, or use job.setInputFormatClass
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;
public void map(LongWritable offset, Text lineText, Context context)
throws IOException, InterruptedException {
String line = lineText.toString();
StringTokenizer tokenizer = new StringTokenizer(line);
while (tokenizer.hasMoreTokens()) {
word.set(tokenizer.nextToken());
context.write(word, one);
context.getCounter(Counters.INPUT_WORDS).increment(1);
}
}
private enum Counters {INPUT_WORDS}
} public static class Reduce extends Reducer<Text, IntWritable, Text, IntWritable> { @Override public void reduce(Text word, Iterable counts, Context context) throws IOException, InterruptedException { int sum = 0; for (IntWritable count : counts) { sum += count.get(); } context.write(word, new IntWritable(sum)); } } } """