RTEditor/src/main/java/com/onegravity/rteditor/utils/io/IOUtils.java
public static byte[] toByteArray(Reader input, Charset encoding) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output, encoding);
        return output.toByteArray();
    }
public static byte[] toByteArray(Reader input, Charset encoding) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        copy(input, output, encoding);
        return output.toByteArray();
    }
Get the contents of a <code>Reader</code> as a <code>byte[]</code>
using the specified character encoding.
<p/>
This method buffers the input internally, so there is no need to use a
<code>BufferedReader</code>.

@param input    the <code>Reader</code> to read from
@param encoding the encoding to use, null means platform default
@return the requested byte array
@throws NullPointerException if the input is null
@throws IOException          if an I/O error occurs
@since 2.3