code: @Nullable
    public static InputStream getMappedInputStream (@Nonnull final File aFile)
    {
      ValueEnforcer.notNull (aFile, "File");
  
      // Open regular
      final FileInputStream aFIS = FileHelper.getInputStream (aFile);
      if (aFIS == null)
        return null;
  
      // Try to memory map it
      final InputStream aIS = _getMappedInputStream (aFIS.getChannel (), aFile);
      if (aIS != null)
        return aIS;
  
      // Memory mapping failed - return the original input stream
      if (LOGGER.isWarnEnabled ())
        LOGGER.warn ("Failed to map file " + aFile + ". Falling though to regular FileInputStream");
      return aFIS;
    }
docs: Get an input stream to the specified file, using memory mapping. If memory
  mapping fails, a regular {@link FileInputStream} is returned.
  
  @param aFile
  The file to use. May not be <code>null</code>.
  @return The Input stream to use.