跟我学hadoop学习5

package v1;
// cc MaxTemperatureMapperV1 First version of a Mapper that passes MaxTemperatureMapperTest
import java.io.IOException;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
//vv MaxTemperatureMapperV1
public class MaxTemperatureMapper
  extends Mapper<LongWritable, Text, Text, IntWritable> {
  
  @Override
  public void map(LongWritable key, Text value, Context context)
      throws IOException, InterruptedException {
    
    String line = value.toString();
    String year = line.substring(15, 19);
    int airTemperature = Integer.parseInt(line.substring(87, 92));
    context.write(new Text(year), new IntWritable(airTemperature));
  }
}
//^^ MaxTemperatureMapperV1



package v1;
//cc MaxTemperatureReducerV1 Reducer for maximum temperature example
import java.io.IOException;

import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

// vv MaxTemperatureReducerV1
public class MaxTemperatureReducer
  extends Reducer<Text, IntWritable, Text, IntWritable> {

  @Override
  public void reduce(Text key, Iterable<IntWritable> values,
      Context context)
      throws IOException, InterruptedException {
    
    int maxValue = Integer.MIN_VALUE;
    for (IntWritable value : values) {
      maxValue = Math.max(maxValue, value.get());
    }
    context.write(key, new IntWritable(maxValue));
  }
}
// ^^ MaxTemperatureReducerV1