hadoop mapreduce模式读取sequence文件

import java.io.IOException;


import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.ReflectionUtils;
import org.apache.mahout.fpm.pfpgrowth.convertors.string.TopKStringPatterns;


public class ReadSeqFile {
String uri = "/home/hadoop/fpdir/output/part-r-00000";


private static SequenceFile.Reader reader = null;
private static Configuration conf = new Configuration();


public static class ReadFileMapper extends
Mapper<LongWritable, Text, Text, Text> {


@Override
public void map(LongWritable key, Text value,Context context) {
Text text = (Text) ReflectionUtils.newInstance(reader.getKeyClass(), conf);
TopKStringPatterns k =  (TopKStringPatterns)ReflectionUtils.newInstance(reader.getValueClass(), conf);
try {
while (reader.next(text, k)) {
//System.out.printf("%s\t%s\n", text, k);

context.write(text, new Text(k.toString()));

//注意这里使用的reader读取的，而不是map方法中的key value

}
} catch (IOException e1) {
e1.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}


}
/**
* @param args
* @throws IOException
* @throws InterruptedException
* @throws ClassNotFoundException
*/
public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {


Job job = new Job(conf,"read seq file");
job.setJarByClass(ReadSeqFile.class);
job.setMapperClass(ReadFileMapper.class);
job.setMapOutputKeyClass(Text.class);

job.setMapOutputValueClass(Text.class);

//配置输出格式

Path path = new Path("/home/hadoop/fpdir/output/part-r-00000");
FileSystem fs = FileSystem.get(conf);
reader = new SequenceFile.Reader(fs, path, conf);
FileInputFormat.addInputPath(job, path);
FileOutputFormat.setOutputPath(job, new Path("/home/hadoop/fpdir/testReadSeq"));
System.exit(job.waitForCompletion(true)?0:1);
} 
}