Redis系列~发布订阅（十一）

谁借莪１个温暖的怀抱￠ 2022-07-15 01:12 139阅读 0赞

Redis 发布订阅(pub/sub)是一种消息通信模式：发送者(pub)发送消息，订阅者(sub)接收消息。

Redis 客户端可以订阅任意数量的频道。

下图展示了频道 channel1 ， 以及订阅这个频道的三个客户端 —— client2 、 client5 和 client1 之间的关系：

![pubsub1][]

当有新消息通过 PUBLISH 命令发送给频道 channel1 时， 这个消息就会被发送给订阅它的三个客户端：

![pubsub2][]

--------------------

## 实例 ##

以下实例演示了发布订阅是如何工作的。在我们实例中我们创建了订阅频道名为 **redisChat**:

redis 127.0.0.1:6379> SUBSCRIBE redisChat
    
    Reading messages... (press Ctrl-C to quit)
    1) "subscribe"
    2) "redisChat"
    3) (integer) 1

现在，我们先重新开启个 redis 客户端，然后在同一个频道 redisChat 发布两次消息，订阅者就能接收到消息。

redis 127.0.0.1:6379> PUBLISH redisChat "Redis is a great caching technique"
    
    (integer) 1
    
    redis 127.0.0.1:6379> PUBLISH redisChat "Learn redis by runoob.com"
    
    (integer) 1
    
    # 订阅者的客户端会显示如下消息
    1) "message"
    2) "redisChat"
    3) "Redis is a great caching technique"
    1) "message"
    2) "redisChat"
    3) "Learn redis by runoob.com"

--------------------

## Redis 发布订阅命令 ##

下表列出了 redis 发布订阅常用命令：

<table style="border:0px; margin:4px 0px; padding:0px; border-collapse:collapse; width:729px; color:rgb(51,51,51); font-family:&quot;Open Sans&quot;,&quot;Helvetica Neue&quot;,Helvetica,Arial,STHeiti,&quot;Microsoft Yahei&quot;,sans-serif; font-size:12px"> 
 <tbody style="border:0px; margin:0px; padding:0px"> 
  <tr style="border:0px; margin:0px; padding:0px; background-color:rgb(246,244,240)"> 
   <th style="border:1px solid rgb(85,85,85); margin:0px; padding:3px; color:rgb(255,255,255); background-color:rgb(85,85,85); vertical-align:top; text-align:left; width:29px"> 序号</th> 
   <th style="border:1px solid rgb(85,85,85); margin:0px; padding:3px; color:rgb(255,255,255); background-color:rgb(85,85,85); vertical-align:top; text-align:left"> 命令及描述</th> 
  </tr> 
  <tr style="border:0px; margin:0px; padding:0px"> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> 1</td> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> <a href="http://www.runoob.com/redis/pub-sub-psubscribe.html" style="border:0px; margin:0px; padding:0px; color:rgb(100,133,76)" rel="nofollow">PSUBSCRIBE pattern [pattern ...]</a>&nbsp;<br> 订阅一个或多个符合给定模式的频道。</td> 
  </tr> 
  <tr style="border:0px; margin:0px; padding:0px; background-color:rgb(246,244,240)"> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> 2</td> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> <a href="http://www.runoob.com/redis/pub-sub-pubsub.html" style="border:0px; margin:0px; padding:0px; color:rgb(100,133,76)" rel="nofollow">PUBSUB subcommand [argument [argument ...]]</a>&nbsp;<br> 查看订阅与发布系统状态。</td> 
  </tr> 
  <tr style="border:0px; margin:0px; padding:0px"> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> 3</td> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> <a href="http://www.runoob.com/redis/pub-sub-publish.html" style="border:0px; margin:0px; padding:0px; color:rgb(100,133,76)" rel="nofollow">PUBLISH channel message</a>&nbsp;<br> 将信息发送到指定的频道。</td> 
  </tr> 
  <tr style="border:0px; margin:0px; padding:0px; background-color:rgb(246,244,240)"> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> 4</td> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> <a href="http://www.runoob.com/redis/pub-sub-punsubscribe.html" style="border:0px; margin:0px; padding:0px; color:rgb(100,133,76)" rel="nofollow">PUNSUBSCRIBE [pattern [pattern ...]]</a>&nbsp;<br> 退订所有给定模式的频道。</td> 
  </tr> 
  <tr style="border:0px; margin:0px; padding:0px"> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> 5</td> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> <a href="http://www.runoob.com/redis/pub-sub-subscribe.html" style="border:0px; margin:0px; padding:0px; color:rgb(100,133,76)" rel="nofollow">SUBSCRIBE channel [channel ...]</a>&nbsp;<br> 订阅给定的一个或多个频道的信息。</td> 
  </tr> 
  <tr style="border:0px; margin:0px; padding:0px; background-color:rgb(246,244,240)"> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> 6</td> 
   <td style="border:1px solid rgb(212,212,212); margin:0px; padding:7px 5px; font-size:1em; word-break:break-all; word-wrap:break-word; vertical-align:top"> <a href="http://www.runoob.com/redis/pub-sub-unsubscribe.html" style="border:0px; margin:0px; padding:0px; color:rgb(100,133,76)" rel="nofollow">UNSUBSCRIBE [channel [channel ...]]</a>&nbsp;<br> 指退订给定的频道。</td> 
  </tr> 
 </tbody> 
</table>

[pubsub1]: /images/20220715/2ae8976ecb5d495ca641904f46ceb42d.png
[pubsub2]: /images/20220715/bc6ec2c0292e42dc81e2dd6a27214bc4.png