guava/src/com/google/common/io/Files.java
public static CharSource asCharSource(File file, Charset charset) {
    return asByteSource(file).asCharSource(charset);
  }
public static CharSource asCharSource(File file, Charset charset) {
    return asByteSource(file).asCharSource(charset);
  }
Returns a new {@link CharSource} for reading character data from the given file using the given
character set.

@since 14.0