guava/src/com/google/common/io/Files.java
@Beta
  public static void copy(File from, OutputStream to) throws IOException {
    asByteSource(from).copyTo(to);
  }
@Beta
  public static void copy(File from, OutputStream to) throws IOException {
    asByteSource(from).copyTo(to);
  }
Copies all bytes from a file to an output stream.

<p><b>{@link java.nio.file.Path} equivalent:</b> {@link
java.nio.file.Files#copy(java.nio.file.Path, OutputStream)}.

@param from the source file
@param to the output stream
@throws IOException if an I/O error occurs