hadoop--mapreduce代码之排序
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 Sort {//map将输入中的value化成IntWritable类型，作为输出的keypublic static class Map extends Mapper<Object,Text,IntWritable,IntWritable>{private static IntWritable data = new IntWritable();public void map(Object key,Text value,Context context) throws IOException,InterruptedException{ String line = value.toString(); data.set(Integer.parseInt(line)); context.write(data, new IntWritable(1));}}//reduce将输入中的key复制到输出的value上，然后根据输入的//value-list中的元素的个数决定key的输出次数//用全局的linenum来代表key的位次public static class Reduce extends Reducer<IntWritable,IntWritable,IntWritable,IntWritable>{private static IntWritable linenum = new IntWritable(1);public void reduce(IntWritable key,Iterable<IntWritable> values,Context context) throws IOException,InterruptedException{for(IntWritable val:values){context.write(linenum, key);linenum = new IntWritable(linenum.get()+1);}}}/** * @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,"Sort");job.setJarByClass(Sort.class);job.setMapperClass(Map.class);job.setCombinerClass(Reduce.class);job.setReducerClass(Reduce.class);job.setOutputKeyClass(IntWritable.class);job.setOutputValueClass(IntWritable.class);FileInputFormat.addInputPath(job, new Path(otherArgs[0]));FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));System.exit(job.waitForCompletion(true) ? 0 : 1);}}