Hadoop:一个目录下的数据只由一个map处理

 @Override
 protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
 FileSystem fs = FileSystem.get(context.getConfiguration());
 for (FileStatus status : fs.listStatus(new Path(value.toString()))) {
 // process file
 }
 }

import java.io.IOException;
import java.util.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.CombineFileSplit;
/**
 * 一个map处理一个目录的数据
 */
public abstract class OneMapOneDirectoryInputFormat extends CombineFileInputFormat {
 private static final Log LOG = LogFactory.getLog(OneMapOneDirectoryInputFormat.class);
 @Override
 protected boolean isSplitable(JobContext context, Path file) {
 return false;
 }
 @Override
 public List getSplits(JobContext job) throws IOException {
 // get all the files in input path
 List stats = listStatus(job);
 List splits = new ArrayList();
 if (stats.size() == 0) {
 return splits;
 }
 LOG.info("fileNums=" + stats.size());
 Map> map = new HashMap>();
 for (FileStatus stat : stats) {
 String directory = stat.getPath().getParent().toString();
 if (map.containsKey(directory)) {
 map.get(directory).add(stat);
 } else {
 List fileList = new ArrayList();
 fileList.add(stat);
 map.put(directory, fileList);
 }
 }
 // 设置inputSplit
 long currentLen = 0;
 List pathLst = new ArrayList();
 List offsetLst = new ArrayList();
 List lengthLst = new ArrayList();
 Iterator itr = map.keySet().iterator();
 while (itr.hasNext()) {
 String dir = itr.next();
 List fileList = map.get(dir);
 for (int i = 0; i < fileList.size(); i++) {
 FileStatus stat = fileList.get(i);
 pathLst.add(stat.getPath());
 offsetLst.add(0L);
 lengthLst.add(stat.getLen());
 currentLen += stat.getLen();
 }
 Path[] pathArray = new Path[pathLst.size()];
 CombineFileSplit thissplit = new CombineFileSplit(pathLst.toArray(pathArray),
 getLongArray(offsetLst), getLongArray(lengthLst), new String[0]);
 LOG.info("combineFileSplit(" + splits.size() + ") fileNum(" + pathLst.size()
 + ") length(" + currentLen + ")");
 for (int i = 0; i < pathArray.length; i++) {
 LOG.info(" -> path[" + i + "]=" + pathArray[i].toString());
 }
 splits.add(thissplit);
 pathLst.clear();
 offsetLst.clear();
 lengthLst.clear();
 currentLen = 0;
 }
 return splits;
 }
 private long[] getLongArray(List lst) {
 long[] rst = new long[lst.size()];
 for (int i = 0; i < lst.size(); i++) {
 rst[i] = lst.get(i);
 }
 return rst;
 }
}