如何为离线模式配置XMPP并从FCM接收通知？
如何使用Smack将IQ Push节发送到XMPP？
<iq type='set' id='123'>
<push xmlns='p1:push'>
<keepalive max="120"/>
<session duration="60"/>
<body send="all" groupchat="true" from="jid"/>
<status type="xa">Text Message when in push mode</status>
<offline>false</offline>
<notification>
<type>gcm</type>
<id>registrationId</id>
</notification>
<appid>applicationId</appid>
</push>
</iq>