认识smack3.0.4基本对象 - Presence

雨点打透心脏的1/2处 2023-10-16 22:33 54阅读 0赞

## 一 Presence对象介绍 ##

与IQ一样，Presence也是继承自XMPP的基类Packet信息包，Presence主要有两个用途：1）告诉服务器所有客户端当前所处的状态，2）发出添加/删除好友请求；每个Presence信息包都有一个类型属性Presence.Type，如下：

*  available: 表示处于在线状态
 *  unavailable: 表示处于离线状态
 *  subscribe: 表示发出添加好友的申请
 *  unsubscribe: 表示发出删除好友的申请
 *  unsubscribed: 表示拒绝添加对方为好友
 *  error: 表示presence信息报中包含了一个错误消息。

除了类型信息外，Presence还包含其他一些可选的属性：

*  Status: 用于表示用户状态的自定义文本，例如：外出吃饭
 *  Priority: 一个表示发送者资源优先级的非负数（我尚未搞明白什么是发送者资源）
 *  Mode: 表示五种状态之一：在线(默认）、聊天、离开、xa (extended away)、请勿打扰

## Represents XMPP presence packets. Every presence packet has a type, which is one of the following values:  `available` \-- (Default) indicates the user is available to receive messages.  `unavailable` \-- the user is unavailable to receive messages.  `subscribe` \-- request subscription to recipient's presence.  `subscribed` \-- grant subscription to sender's presence.  `unsubscribe` \-- request removal of subscription to sender's presence.  `unsubscribed` \-- grant removal of subscription to sender's presence.  `error` \-- the presence packet contains an error message.  A number of attributes are optional:  Status -- free-form text describing a user's presence (i.e., gone to lunch).  Priority -- non-negative numerical priority of a sender's resource. The highest resource priority is the default recipient of packets not addressed to a particular resource.  Mode -- one of five presence modes: `available` (the default), `chat`, `away`, `xa` (extended away), and `dnd` (do not disturb).      ##