DictionaryMapper.java

package mia.clustering.ch12.lastfm;

import java.io.IOException;
import java.util.regex.Pattern;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;

public class DictionaryMapper extends
    Mapper<LongWritable,Text,Text,IntWritable> {
  private Pattern splitter;
  
  @Override
  protected void map(LongWritable key, Text line, Context context) throws IOException,
                                                                  InterruptedException {
    String[] fields = splitter.split(line.toString());
    if (fields.length < 4) {
      context.getCounter("Map", "LinesWithErrors").increment(1);
      return;
    }
    String artist = fields[1];
    context.write(new Text(artist), new IntWritable(0));
  }
  
  @Override
  protected void setup(Context context) throws IOException,
                                       InterruptedException {
    super.setup(context);
    splitter = Pattern.compile("<sep>");
  }
}