RabbitMQ各种交换机类型Exchange Types介绍

港控/mmm° 2022-07-12 03:10 156阅读 0赞

最新版本的RabbitMQ有四种交换机类型，分别是Direct exchange、Fanout exchange、Topic exchange、Headers exchange。

**Direct Exchange** – 处理路由键。需要将一个队列绑定到交换机上，要求该消息与一个特定的路由键完全匹配。这是一个完整的匹配。如果一个队列绑定到该交换机上要求路由键 “dog”，则只有被标记为“dog”的消息才被转发，不会转发dog.puppy，也不会转发dog.guard，只会转发dog。   
  
![0ec0f465-49c6-361c-ae2b-dd951a6ed1a9.png][]

**Fanout Exchange** – 不处理路由键。你只需要简单的将队列绑定到交换机上。一个发送到交换机的消息都会被转发到与该交换机绑定的所有队列上。很像子网广播，每台子网内的主机都获得了一份复制的消息。Fanout交换机转发消息是最快的。   
  
![0bbdcd3d-9fc6-3107-b7e0-db67c174d46a.png][]

**Topic Exchange** – 将路由键和某模式进行匹配。此时队列需要绑定要一个模式上。符号“\#”匹配一个或多个词，符号“\*”匹配不多不少一个词。因此“audit.\#”能够匹配到“audit.irs.corporate”，但是“audit.\*” 只会匹配到“audit.irs”。我在RedHat的朋友做了一张不错的图，来表明topic交换机是如何工作的：   
  
![11171ab4-af07-3ff6-bdf6-d1febda679c3.png][]

注：这种情况下队列会收到所有路由器中符合topic规则的消息

**Headers exchange** – 还没有仔细研究过，复制点官方的介绍吧。

A headers exchange is designed to for routing on multiple attributes that are more easily expressed as message headers than a routing key. Headers exchanges ignore the routing key attribute. Instead, the attributes used for routing are taken from the headers attribute. A message is considered matching if the value of the header equals the value specified upon binding.

It is possible to bind a queue to a headers exchange using more than one header for matching. In this case, the broker needs one more piece of information from the application developer, namely, should it consider messages with any of the headers matching, or all of them? This is what the “x-match” binding argument is for. When the “x-match” argument is set to “any”, just one matching header value is sufficient. Alternatively, setting “x-match” to “all” mandates that all the values must match.

Headers exchanges can be looked upon as “direct exchanges on steroids”. Because they route based on header values, they can be used as direct exchanges where the routing key does not have to be a string; it could be an integer or a hash (dictionary) for example.

其实除了上面四种以外还有一种**Default Exchange**，它是一种特别的Direct Exchange。

当你手动创建一个队列时，后台会自动将这个队列绑定到一个名称为空的Direct类型交换机上，绑定路由名称与队列名称相同。有了这个默认的交换机和绑定，我们就可以像其他轻量级的队列，如[Redis][]那样，直接操作队列来处理消息。不过只是看起来是，实际上在RabbitMQ里直接操作是不可能的。消息始终都是先发送到交换机，由交换级经过路由传送给队列，消费者再从队列中获取消息的。不过由于这个默认交换机和路由的关系，使我们只关心队列这一层即可，这个比较适合做一些简单的应用，毕竟没有发挥RabbitMQ的最大功能，如果都用这种方式去使用的话就真是杀鸡用宰牛刀了。

参考：

[https://www.rabbitmq.com/tutorials/amqp-concepts.html][https_www.rabbitmq.com_tutorials_amqp-concepts.html]

[http://melin.iteye.com/blog/691265][http_melin.iteye.com_blog_691265]

[0ec0f465-49c6-361c-ae2b-dd951a6ed1a9.png]: /images/20220711/ac3453eb7dca4db3a74a3fe36b3d95e7.png
[0bbdcd3d-9fc6-3107-b7e0-db67c174d46a.png]: /images/20220711/e3a7af546de241cfa2d43af840c16d7f.png
[11171ab4-af07-3ff6-bdf6-d1febda679c3.png]: /images/20220711/002419dbd0784471b74e77378d1b1731.png
[Redis]: http://lib.csdn.net/base/redis
[https_www.rabbitmq.com_tutorials_amqp-concepts.html]: https://www.rabbitmq.com/tutorials/amqp-concepts.html
[http_melin.iteye.com_blog_691265]: http://melin.iteye.com/blog/691265