code: static BlockFactory createFactory(COSAPIClient owner,
        String name) {
      switch (name) {
        case COSConstants.FAST_UPLOAD_BUFFER_ARRAY:
          return new ArrayBlockFactory(owner);
        case COSConstants.FAST_UPLOAD_BUFFER_DISK:
          return new DiskBlockFactory(owner);
        default:
          throw new IllegalArgumentException("Unsupported block buffer"
              + " \"" + name + '"');
      }
    }
docs: Create a factory.
  @param owner factory owner
  @param name factory name -the option from {@link Constants}
  @return the factory, ready to be initialized
  @throws IllegalArgumentException if the name is unknown