final int flag = buf.getInt();
String attribute = null;
int payLoadOffset = offset + HEADER_LEN;
int payLoadLen = msgLen;
if (payLoadLen > MAX_READ_BUFFER_SIZE) {
throw new InvalidMessageException("Too much long payload length:" + payLoadLen);
}
// ��������ԣ���Ҫ��������
if (MessageFlagUtils.hasAttribute(flag)) {
// ȡ4���ֽڵ����Գ���
final int attrLen = getInt(offset + HEADER_LEN, data);