BasicFormatMatcher.java 文件源码

public boolean matches(DrillFileSystem fs, FileStatus status) throws IOException{
  if (ranges.isEmpty()) {
    return false;
  }
  final Range<Long> fileRange = Range.closedOpen( 0L, status.getLen());

  try (FSDataInputStream is = fs.open(status.getPath())) {
    for(RangeMagics rMagic : ranges) {
      Range<Long> r = rMagic.range;
      if (!fileRange.encloses(r)) {
        continue;
      }
      int len = (int) (r.upperEndpoint() - r.lowerEndpoint());
      byte[] bytes = new byte[len];
      is.readFully(r.lowerEndpoint(), bytes);
      for (byte[] magic : rMagic.magics) {
        if (Arrays.equals(magic, bytes)) {
          return true;
        }
      }
    }
  }
  return false;
}