hadoop--mapredduce代码之数据去重

package com.hadoop.sample;import java.io.IOException;import java.util.StringTokenizer;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.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;import org.apache.hadoop.util.GenericOptionsParser;public class Dedup {//map将输入中的value复制到输出数据的key上，并直接输出public static class Map extends Mapper<Object,Text,Text,Text>{private static Text line = new Text();public void map(Object key,Text value,Context context) throws IOException,InterruptedException{line = value;context.write(line, new Text(""));}}//reduce将输入中的key复制到输出数据的key上，并直接输出public static class Reduce extends Reducer<Text,Text,Text,Text>{public void reduce(Text key,Iterable<Text> values,Context context) throws IOException,InterruptedException{context.write(key, new Text(""));}}/** * @param args */public static void main(String[] args) throws Exception{// TODO Auto-generated method stubConfiguration conf = new Configuration();String[] otherArgs = new GenericOptionsParser(conf,args).getRemainingArgs();if(otherArgs.length != 2){System.err.println("Usage WordCount <int> <out>");System.exit(2);}Job job = new Job(conf,"Dedup");job.setJarByClass(Dedup.class);job.setMapperClass(Map.class);job.setCombinerClass(Reducer.class);job.setReducerClass(Reducer.class);job.setOutputKeyClass(Text.class);job.setOutputValueClass(Text.class);FileInputFormat.addInputPath(job, new Path(otherArgs[0]));FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));System.exit(job.waitForCompletion(true) ? 0 : 1);}}