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key public 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 stub Configuration 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); } }
hadoop--mapreduce代码之排序
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