Hadoop--引用计数

package com.smartmap.example;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
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.Reducer.Context;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;


public class CiteCount {
	public static class MapClass extends Mapper<Text, Text, Text, Text> {

		public void map(Text key, Text value, Context context) throws IOException, InterruptedException {
			context.write(value, key);			
		}
	}

	public static class ReduceClass extends Reducer<Text, Text, Text, IntWritable> {
		public void reduce(Text key, Iterable<Text> values,Context context) throws IOException, InterruptedException {
			int count = 0;
			for (Text val : values) {
				count++;
			}
			context.write(key, new IntWritable(count));
		}
	}

	public static void main(String[] args) throws Exception {
		Configuration conf = new Configuration();
		String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
		if (otherArgs.length != 2) {
			System.err.println("Usage: CiteCount <int> <out>");
			System.exit(2);
		}
		conf.set("key.value.separator.in.input.line", ",");
		Path in = new Path(args[0]);
		Path out = new Path(args[1]);
		Job job = new Job(conf);
		job.setJarByClass(CiteCount.class);
		job.setMapperClass(MapClass.class);
		job.setReducerClass(ReduceClass.class);
		job.setInputFormatClass(KeyValueTextInputFormat.class);
		job.setOutputFormatClass(TextOutputFormat.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(Text.class);
		FileInputFormat.addInputPath(job, in);
		FileOutputFormat.setOutputPath(job, out);
		System.exit(job.waitForCompletion(true) ? 0 : 1);

	}
}

 

 

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hdfs://192.168.1.30:9000/data/cite /opt/eclipse/workspace/data/out