HFileInputFormat实现

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.hbase.KeyValue;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.io.hfile.CacheConfig;
import org.apache.hadoop.hbase.io.hfile.HFile;
import org.apache.hadoop.hbase.io.hfile.HFileScanner;
import org.apache.hadoop.hbase.regionserver.metrics.SchemaMetrics;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.FileSplit;

/**
* This is direct port (hopefully) of the Scala version of this class available
* on https://gist.github.com/1120311 *
* @author yuankang
*/
public class HFileInputFormat extends FileInputFormat<ImmutableBytesWritable, KeyValue> {

private class HFileRecordReader extends
RecordReader<ImmutableBytesWritable, KeyValue> {

private HFile.Reader reader;
private final HFileScanner scanner;
private int entryNumber = 0;

public HFileRecordReader(FileSplit split, Configuration conf)
throws IOException {
SchemaMetrics.configureGlobally(conf);
final Path path = split.getPath();
reader = HFile.createReader(FileSystem.get(conf), path, new CacheConfig(conf));

scanner = reader.getScanner(false, false);
reader.loadFileInfo(); // This is required or else seekTo throws a
// NPE
scanner.seekTo(); // This is required or else scanner.next throws an
// error
}

@Override
public void close() throws IOException {
if (reader != null) {
reader.close();
}
}

/*
* @Override public boolean next(ImmutableBytesWritable key, KeyValue
* value) throws IOException { entryNumber++; return scanner.next(); }
*/

@Override
public ImmutableBytesWritable getCurrentKey() throws IOException,
InterruptedException {
// TODO Auto-generated method stub
return new ImmutableBytesWritable(scanner.getKeyValue().getRow());
}

@Override
public KeyValue getCurrentValue() throws IOException,
InterruptedException {
// TODO Auto-generated method stub
return scanner.getKeyValue();
}

@Override
public boolean nextKeyValue() throws IOException, InterruptedException {
// TODO Auto-generated method stub
entryNumber++;
return scanner.next();
}

@Override
public float getProgress() throws IOException, InterruptedException {
// TODO Auto-generated method stub
if (reader != null) {
return (entryNumber / reader.getEntries());
}
return 1;
}

@Override
public void initialize(InputSplit arg0, TaskAttemptContext arg1)
throws IOException, InterruptedException {

}

}

@Override
protected boolean isSplitable(JobContext context, Path filename) {
return false;
}

@Override
public RecordReader<ImmutableBytesWritable, KeyValue> createRecordReader(InputSplit split,
TaskAttemptContext context) throws IOException,
InterruptedException {
return new HFileRecordReader((FileSplit) split,
context.getConfiguration());
}

}