hadoop--mapreduce代码：WordCount

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 WordCount {//继承mapper接口，设置map的输入类型为<Object,Text>//输出类型为<Text,IntWritable>public static class Map extends Mapper<Object,Text,Text,IntWritable>{//one表示单词出现一次private static IntWritable one = new IntWritable(1);//word存储切下的单词private Text word = new Text();public void map(Object key,Text value,Context context) throws IOException,InterruptedException{//对输入的行切词StringTokenizer st = new StringTokenizer(value.toString());while(st.hasMoreTokens()){word.set(st.nextToken());//切下的单词存入wordcontext.write(word, one);}}}//继承reducer接口，设置reduce的输入类型<Text,IntWritable>//输出类型为<Text,IntWritable>public static class Reduce extends Reducer<Text,IntWritable,Text,IntWritable>{//result记录单词的频数private static IntWritable result = new IntWritable();public void reduce(Text key,Iterable<IntWritable> values,Context context) throws IOException,InterruptedException{int sum = 0;//对获取的<key,value-list>计算value的和for(IntWritable val:values){sum += val.get();}//将频数设置到resultresult.set(sum);//收集结果context.write(key, result);}}/** * @param args */public static void main(String[] args) throws Exception{// TODO Auto-generated method stubConfiguration conf = new Configuration();//检查运行命令String[] otherArgs = new GenericOptionsParser(conf,args).getRemainingArgs();if(otherArgs.length != 2){System.err.println("Usage WordCount <int> <out>");System.exit(2);}//配置作业名Job job = new Job(conf,"word count");//配置作业各个类job.setJarByClass(WordCount.class);job.setMapperClass(Map.class);job.setCombinerClass(Reduce.class);job.setReducerClass(Reduce.class);job.setOutputKeyClass(Text.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);}}