python使用rabbitMQ介绍五（话题模式）

一、模式介绍

话题模式（Topic）基本思想和路由模式是一样的，只不过路由键支持模糊匹配，符号“#”匹配一个或多个词，符号“*”匹配不多不少一个词

 话题模式相当于消息的模糊匹配，或者按照正则匹配。其中

# 是通配符，匹配一个或者多个单词

* 代表匹配一个单词

模式提醒：

当使用#来收消息时，会接收到所有的消息，这样和fanout模式一样了。

当routing key中不含*或者#时，则topic的模式退化为direct的一对一模式。

队列模型：

 

二、代码示例

 发布者：

#!/usr/bin/env python
import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()

channel.exchange_declare(exchange='topic_logs',
                         exchange_type='topic')

routing_key = ['#', "kern.critical", "A critical kernel error"]
for i in range(10):
    message = '{} msg at : routing key {}'.format(i, routing_key[i % 3])
    channel.basic_publish(exchange='topic_logs',
                          routing_key=routing_key[i % 3],
                          body=message)
    print(" [x] Sent :%r" % (message))
connection.close()

消费者：

import pika
import sys

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
channel = connection.channel()

channel.exchange_declare(exchange='topic_logs',
                         exchange_type='topic')

result = channel.queue_declare(exclusive=True)
queue_name = result.method.queue

binding_key = "#"

channel.queue_bind(exchange='topic_logs',
                   queue=queue_name,
                   routing_key=binding_key)

print(' [*] Waiting for logs. To exit press CTRL+C')

def callback(ch, method, properties, body):
    print(" [x] %r:%r" % (method.routing_key, body))

channel.basic_consume(callback,
                      queue=queue_name,
                      no_ack=True)

channel.start_consuming()

发布者输出：

[x] Sent :'0 msg at : routing key #'
 [x] Sent :'1 msg at : routing key kern.critical'
 [x] Sent :'2 msg at : routing key error.critical'
 [x] Sent :'3 msg at : routing key #'
 [x] Sent :'4 msg at : routing key kern.critical'
 [x] Sent :'5 msg at : routing key error.critical'
 [x] Sent :'6 msg at : routing key #'
 [x] Sent :'7 msg at : routing key kern.critical'
 [x] Sent :'8 msg at : routing key error.critical'
 [x] Sent :'9 msg at : routing key #'

消费者输出：

all：可以看到接收到所有的消息

[*] Waiting for logs. To exit press CTRL+C
 [x] '#':b'0 msg at : routing key #'
 [x] 'kern.critical':b'1 msg at : routing key kern.critical'
 [x] 'error.critical':b'2 msg at : routing key error.critical'
 [x] '#':b'3 msg at : routing key #'
 [x] 'kern.critical':b'4 msg at : routing key kern.critical'
 [x] 'error.critical':b'5 msg at : routing key error.critical'
 [x] '#':b'6 msg at : routing key #'
 [x] 'kern.critical':b'7 msg at : routing key kern.critical'
 [x] 'error.critical':b'8 msg at : routing key error.critical'
 [x] '#':b'9 msg at : routing key #'

消费者“critical”，只接收含critical的消息

[*] Waiting for logs. To exit press CTRL+C
 [x] 'kern.critical':b'1 msg at : routing key kern.critical'
 [x] 'error.critical':b'2 msg at : routing key error.critical'
 [x] 'kern.critical':b'4 msg at : routing key kern.critical'
 [x] 'error.critical':b'5 msg at : routing key error.critical'
 [x] 'kern.critical':b'7 msg at : routing key kern.critical'
 [x] 'error.critical':b'8 msg at : routing key error.critical'

消费者“kern”，只接收含kern的消息

[*] Waiting for logs. To exit press CTRL+C
 [x] 'kern.critical':b'1 msg at : routing key kern.critical'
 [x] 'kern.critical':b'4 msg at : routing key kern.critical'
 [x] 'kern.critical':b'7 msg at : routing key kern.critical'

三、队列信息

 在管理页面上可以看到三个队列信息，routing key对应着三个队列的配置