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一、模式介绍

路由模式,与发布-订阅模式一样,消息发送到exchange中,消费者把队列绑定到exchange上。

这种模式在exchange上添加添加了一个路由键(routing-key),生产者发布消息的时候添加路由键(routing-key),消费者绑定队列到交换机时添加键值(routing-key),这样就可以接收到对应的消息。

路由模式的direct exchange。

队列模型:

 

 

 

与发布-订阅模式不同的是,每个消费者队列接收的消息不同,根据消息的routing-key把消息发送到不同的队列中。

当所有的消费队列绑定的routing-key一样时,路由模式行为与发布-订阅模式一样。

 

二、代码示意 

发布者:不再创建队列,发送消息到exchange(交换机)中。exchange_type为direct。

 1 import pika
 2 import sys
 3 
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
 5 channel = connection.channel()
 6 
 7 channel.exchange_declare(exchange='direct_logs',
 8                          exchange_type='direct')
 9 
10 severity = ['info', 'warning', 'error']
11 for i in range(20):
12     message = '{} Hello World! {}'.format(i, severity[i % 3])
13     channel.basic_publish(exchange='direct_logs',
14                           routing_key=severity[i % 3],
15                           body=message)
16     print(" [x] Sent: {}".format(message))
17 connection.close()

 

每个消费者绑定的队列定义不同的routing-key,接收到不同的消息。

以info为示例:

 1 import pika
 2 import sys
 3 
 4 connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
 5 channel = connection.channel()
 6 
 7 channel.exchange_declare(exchange='direct_logs',
 8                          exchange_type='direct')
 9 
10 result = channel.queue_declare(exclusive=True)
11 queue_name = result.method.queue
12 
13 channel.queue_bind(exchange='direct_logs',
14                    queue=queue_name,
15                    routing_key='info')
16 
17 print(' [*] Waiting for logs. To exit press CTRL+C')
18 
19 def callback(ch, method, properties, body):
20     print(" [x] %r:%r" % (method.routing_key, body))
21 
22 channel.basic_consume(callback,
23                       queue=queue_name,
24                       no_ack=True)
25 
26 channel.start_consuming()

 

执行结果输出:

发布者:

[x] Sent: 0 Hello World! info
 [x] Sent: 1 Hello World! warning
 [x] Sent: 2 Hello World! error
 [x] Sent: 3 Hello World! info
 [x] Sent: 4 Hello World! warning
 [x] Sent: 5 Hello World! error
 [x] Sent: 6 Hello World! info
 [x] Sent: 7 Hello World! warning
 [x] Sent: 8 Hello World! error
 [x] Sent: 9 Hello World! info
 [x] Sent: 10 Hello World! warning
 [x] Sent: 11 Hello World! error
 [x] Sent: 12 Hello World! info
 [x] Sent: 13 Hello World! warning
 [x] Sent: 14 Hello World! error
 [x] Sent: 15 Hello World! info
 [x] Sent: 16 Hello World! warning
 [x] Sent: 17 Hello World! error
 [x] Sent: 18 Hello World! info
 [x] Sent: 19 Hello World! warning

 

Info输出:

[*] Waiting for logs. To exit press CTRL+C
 [x] 'info':b'0 Hello World! info'
 [x] 'info':b'3 Hello World! info'
 [x] 'info':b'6 Hello World! info'
 [x] 'info':b'9 Hello World! info'
 [x] 'info':b'12 Hello World! info'
 [x] 'info':b'15 Hello World! info'
 [x] 'info':b'18 Hello World! info'

Warning输出:

[*] Waiting for logs. To exit press CTRL+C
 [x] 'warning':b'1 Hello World! warning'
 [x] 'warning':b'4 Hello World! warning'
 [x] 'warning':b'7 Hello World! warning'
 [x] 'warning':b'10 Hello World! warning'
 [x] 'warning':b'13 Hello World! warning'
 [x] 'warning':b'16 Hello World! warning'
 [x] 'warning':b'19 Hello World! warning'

Error输出:

[*] Waiting for logs. To exit press CTRL+C
 [x] 'error':b'2 Hello World! error'
 [x] 'error':b'5 Hello World! error'
 [x] 'error':b'8 Hello World! error'
 [x] 'error':b'11 Hello World! error'
 [x] 'error':b'14 Hello World! error'
 [x] 'error':b'17 Hello World! error'

 

可以看到,不同的消费者收到不同级别的日志信息。

 

三、队列信息

管理页面,exchange页面,点击“direct_logs”上查看队列情况,可以看到三个不同routing_key的队列

routing key列展示了对应的key。