mapreduce 顺序组合

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 Driver {

public static class TokenizerMapper extends
Mapper<Object, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
while (itr.hasMoreTokens()) {
word.set(itr.nextToken());
context.write(word, one);
}
}
}

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

public static class SequenceMapper extends
Mapper<Object, Text, Text, Text> {
private Text word = new Text();
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String []sep=value.toString().split("\t");
word.set(sep[1]+"\t"+sep[0]);
System.out.println(value.toString());
context.write(word,new Text(""));
}
}

public static class SequenceReducer extends
Reducer<Text,Text,Text,Text> {
public void reduce(Text key, Iterable<Text> values,
Context context) throws IOException, InterruptedException {
String[] sep = key.toString().split("\t");
System.out.println( sep[0]+"++++++++="+ sep[1]);
context.write(key,new Text(""));
}
}

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: wordcount <in> <out>");
System.exit(2);
}
Job job = new Job(conf, "word count");
job.setJarByClass(Driver.class);
job.setMapperClass(TokenizerMapper.class);
job.setCombinerClass(IntSumReducer.class);
job.setReducerClass(IntSumReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.addInputPath(job, new Path(otherArgs[0]));
FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));
job.waitForCompletion(true);

Configuration conf2 = new Configuration();
Job job2 = new Job(conf2, "word count1");
job2.setJarByClass(Driver.class);
job2.setMapperClass(SequenceMapper.class);
job2.setReducerClass(SequenceReducer.class);
job2.setOutputKeyClass(Text.class);
job2.setOutputValueClass(Text.class);
FileInputFormat.addInputPath(job2, new Path(otherArgs[1]));
FileOutputFormat.setOutputPath(job2, new Path(otherArgs[2]));
job2.waitForCompletion(true);
}
}