SegmentReader.java 文件源码

private List<Writable> getMapRecords(Path dir, Text key) throws Exception {
  MapFile.Reader[] readers = MapFileOutputFormat.getReaders(fs, dir,
      getConf());
  ArrayList<Writable> res = new ArrayList<Writable>();
  Class<?> keyClass = readers[0].getKeyClass();
  Class<?> valueClass = readers[0].getValueClass();
  if (!keyClass.getName().equals("org.apache.hadoop.io.Text"))
    throw new IOException("Incompatible key (" + keyClass.getName() + ")");
  Writable value = (Writable) valueClass.newInstance();
  // we don't know the partitioning schema
  for (int i = 0; i < readers.length; i++) {
    if (readers[i].get(key, value) != null) {
      res.add(value);
      value = (Writable) valueClass.newInstance();
      Text aKey = (Text) keyClass.newInstance();
      while (readers[i].next(aKey, value) && aKey.equals(key)) {
        res.add(value);
        value = (Writable) valueClass.newInstance();
      }
    }
    readers[i].close();
  }
  return res;
}