一、用戶添加刪除好友是發送Presence包，由PresenceSubscribeHandler和IQRosterHandler處理
<iq id="fDsuy-48" type="set"><query xmlns="jabber:iq:roster"><item jid="[email protected]" name="shiwenli01"><group>Friends</group></item></query></iq>
<presence id="fDsuy-49" to="[email protected]" type="subscribe"></presence>