Hadoop 中自定義倒序排序 demo

SortMR

package cn.itcast.hadoop.mr.flowsort;

import java.io.IOException;

import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
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.output.FileOutputFormat;

import cn.itcast.hadoop.mr.flowsum.FlowBean;

public class SortMR {

	public static class SortMapper extends Mapper<LongWritable, Text, FlowBean, NullWritable> {

		// 拿到一行數據，切分出各字段，封裝爲一個 flowbean ，做爲 key 輸出
		@Override
		protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

			String line = value.toString();

			String[] fields = StringUtils.split(line, "\t");

			String phoneNB = fields[0];
			long u_flow = Long.parseLong(fields[1]);
			long d_flow = Long.parseLong(fields[2]);

			context.write(new FlowBean(phoneNB, u_flow, d_flow), NullWritable.get());//map 全部數據緩存起來，排完序，再給 reduce 。

		}

	}

	public static class SortReducer extends Reducer<FlowBean, NullWritable, Text, FlowBean> {

		@Override
		protected void reduce(FlowBean key, Iterable<NullWritable> values, Context context)
				throws IOException, InterruptedException {

			String phoneNB = key.getPhoneNB();
			context.write(new Text(phoneNB), key);

		}

	}

	public static void main(String[] args) throws Exception {

		Configuration conf = new Configuration();
		Job job = Job.getInstance(conf);

		job.setJarByClass(SortMR.class);

		job.setMapperClass(SortMapper.class);
		job.setReducerClass(SortReducer.class);

		job.setMapOutputKeyClass(FlowBean.class);
		job.setMapOutputValueClass(NullWritable.class);

		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(FlowBean.class);

		FileInputFormat.setInputPaths(job, new Path(args[0]));
		FileOutputFormat.setOutputPath(job, new Path(args[1]));

		System.exit(job.waitForCompletion(true) ? 0 : 1);

	}

}

打包成一個  jar  包

輸出命令、結果：