* @param key ������
* @return ����ֵ���ֽ����飬������������ڣ���<code>null</code>
* @throws UnsupportedEncodingException ���ָ���˴���ı����ַ���
*/
public byte[] getBytes(String key) throws UnsupportedEncodingException {
ValueList container = getValueList(key, false);
return container == null ? EMPTY_BYTE_ARRAY : container.getBytes(getCharacterEncoding());
}