Q9EmpSalarySort.java

package com.elon33.mr1;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
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.io.WritableComparable;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

public class Q9EmpSalarySort extends Configured implements Tool {

	public static class MapClass extends Mapper<LongWritable, Text, IntWritable, Text> {

		public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

			String[] kv = value.toString().split(",");

			int empAllSalary = "".equals(kv[6]) ? Integer.parseInt(kv[5]) : Integer.parseInt(kv[5]) + Integer.parseInt(kv[6]);
			context.write(new IntWritable(empAllSalary), new Text(kv[1]));
		}
	}

	public static class DecreaseComparator extends IntWritable.Comparator {
		public int compare(WritableComparable a, WritableComparable b) {
			return -super.compare(a, b);
		}

		public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
			return -super.compare(b1, s1, l1, b2, s2, l2);
		}
	}

	@Override
	public int run(String[] args) throws Exception {

		Job job = new Job(getConf(), "Q9EmpSalarySort");
		job.setJobName("Q9EmpSalarySort");

		job.setJarByClass(Q9EmpSalarySort.class);
		job.setMapperClass(MapClass.class);

		job.setMapOutputKeyClass(IntWritable.class);
		job.setMapOutputValueClass(Text.class);
		job.setSortComparatorClass(DecreaseComparator.class);	// 排序规则：倒排

		String[] otherArgs = new GenericOptionsParser(job.getConfiguration(), args).getRemainingArgs();
		FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
		FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));

		job.waitForCompletion(true);
		return job.isSuccessful() ? 0 : 1;
	}

	public static void main(String[] args) throws Exception {
		int res = ToolRunner.run(new Configuration(), new Q9EmpSalarySort(), args);
		System.exit(res);
	}
}