* @param out
     *            ライター
     * @return コピーした文字数
     */
    protected static int copyInternal(final Reader in, final Writer out) {
        try {
            final char[] buf = new char[DEFAULT_BUF_SIZE];
            int len;
            int amount = 0;
            while ((len = in.read(buf)) != -1) {
                out.write(buf, 0, len);
                amount += len;
            }