guava/src/com/google/common/io/Files.java
@Beta
  public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
    return mapInternal(file, mode, -1);
  }
@Beta
  public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
    return mapInternal(file, mode, -1);
  }
Fully maps a file in to memory as per {@link
FileChannel#map(java.nio.channels.FileChannel.MapMode, long, long)} using the requested {@link
MapMode}.

<p>Files are mapped from offset 0 to its length.

<p>This only works for files ≤ {@link Integer#MAX_VALUE} bytes.

@param file the file to map
@param mode the mode to use when mapping {@code file}
@return a buffer reflecting {@code file}
@throws FileNotFoundException if the {@code file} does not exist
@throws IOException if an I/O error occurs
@see FileChannel#map(MapMode, long, long)
@since 2.0