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Learn redisson from scratch ------- topics (subscription and distribution)

2022-07-24 17:59:00 【51CTO】

One 、Redisson As message middleware

little does one think Redisson Actually, it has the function of subscription and publishing , Be similar to RabbitMQ. I was using Redis When , You can use List The left in right out feature of this data type , Be able to do message oriented middleware . I don't know this time Redisson Is the bottom layer implemented in this way .Redis Implement middleware gateway ： The fourth quarter, List As message middleware

Let me assume that a user object is pushed . The implementation idea is to transmit the front end to a user ID To come over . We found this user in the database , Then insert the user object Redisson In the message queue of . Write another listener , Keep getting messages from the queue .

Two 、 Technical reference points

       
        Technical reference documents .
       
       RTopic 
       
       topic 
       
       = 
       
       redisson.
       
       getTopic(
       
       "anyTopic");
       
       topic.
       
       addListener(
       
       SomeObject.
       
       class, 
       
       new 
       
       MessageListener
       
       <
       
       SomeObject
       
       >() {
       
       @Override
       
       public 
       
       void 
       
       onMessage(
       
       String 
       
       channel, 
       
       SomeObject 
       
       message) {
       
       //...
       
    }
       
});
       
       //  In other threads or JVM node 
       
       RTopic 
       
       topic 
       
       = 
       
       redisson.
       
       getTopic(
       
       "anyTopic");
       
       long 
       
       clientsReceivedMessage 
       
       = 
       
       topic.
       
       publish(
       
       new 
       
       SomeObject());
      
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actual combat ： Production code

Core code TopicService. Method accepts a user object . And then through Redisson Client's getTopic Method to get RTopic object . Finally, we need to push MUser object , Use RTopic Object's publish Method to join the message queue . Refer to the above documents .

       
       package 
       
       com.
       
       tyzhou.
       
       redisson.
       
       service;
       
       import 
       
       com.
       
       tyzhou.
       
       Constant;
       
       import 
       
       com.
       
       tyzhou.
       
       mail.
       
       modol.
       
       MUser;
       
       import 
       
       org.
       
       apache.
       
       commons.
       
       lang3.
       
       StringUtils;
       
       import 
       
       org.
       
       redisson.
       
       api.
       
       RTopic;
       
       import 
       
       org.
       
       redisson.
       
       api.
       
       RedissonClient;
       
       import 
       
       org.
       
       springframework.
       
       beans.
       
       factory.
       
       annotation.
       
       Autowired;
       
       import 
       
       org.
       
       springframework.
       
       stereotype.
       
       Service;
       
       @Service
       
       public 
       
       class 
       
       TopicService {
       
       @Autowired
       
       private 
       
       RedissonClient 
       
       redisson;
       
       public 
       
       void 
       
       sendEmail(
       
       MUser 
       
       user) {
       
       if (
       
       user 
       
       != 
       
       null 
       
       && 
       
       StringUtils.
       
       isNotBlank(
       
       user.
       
       getEmail())) {
       
       RTopic
       
       <
       
       MUser
       
       > 
       
       topic 
       
       = 
       
       redisson.
       
       getTopic(
       
       Constant.
       
       REDISSON_EMAIL);
       
       topic.
       
       publish(
       
       user);
       
        }
       
    }
       
}
      
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actual combat ： Consumer code

In order to let us have an object similar to a listener , We can implement a system called ApplicationRunner Interface , Then the implementation class will always be in memory .

Realization Ordered The interface makes a sequence for it , Because there may be more than one ApplicationRunner Implementation class of interface .

       
        Technical reference documents ：
       
       RTopic 
       
       topic 
       
       = 
       
       redisson.
       
       getTopic(
       
       "anyTopic");
       
       topic.
       
       addListener(
       
       SomeObject.
       
       class, 
       
       new 
       
       MessageListener
       
       <
       
       SomeObject
       
       >() {
       
       @Override
       
       public 
       
       void 
       
       onMessage(
       
       String 
       
       channel, 
       
       SomeObject 
       
       message) {
       
       //...
       
    }
       
});
      
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       import 
       
       com.
       
       tyzhou.
       
       Constant;
       
       import 
       
       com.
       
       tyzhou.
       
       mail.
       
       modol.
       
       MUser;
       
       import 
       
       org.
       
       redisson.
       
       api.
       
       RTopic;
       
       import 
       
       org.
       
       redisson.
       
       api.
       
       RedissonClient;
       
       import 
       
       org.
       
       redisson.
       
       api.
       
       listener.
       
       MessageListener;
       
       import 
       
       org.
       
       slf4j.
       
       Logger;
       
       import 
       
       org.
       
       slf4j.
       
       LoggerFactory;
       
       import 
       
       org.
       
       springframework.
       
       beans.
       
       factory.
       
       annotation.
       
       Autowired;
       
       import 
       
       org.
       
       springframework.
       
       boot.
       
       ApplicationArguments;
       
       import 
       
       org.
       
       springframework.
       
       boot.
       
       ApplicationRunner;
       
       import 
       
       org.
       
       springframework.
       
       core.
       
       Ordered;
       
       import 
       
       org.
       
       springframework.
       
       stereotype.
       
       Service;
       
       @Service
       
       public 
       
       class 
       
       TopicListener 
       
       implements 
       
       ApplicationRunner, 
       
       Ordered {
       
       private 
       
       static 
       
       final 
       
       Logger 
       
       LOGGER 
       
       = 
       
       LoggerFactory.
       
       getLogger(
       
       TopicListener.
       
       class);
       
       @Autowired
       
       private 
       
       RedissonClient 
       
       redisson;
       
       @Override
       
       public 
       
       void 
       
       run(
       
       ApplicationArguments 
       
       applicationArguments) 
       
       throws 
       
       Exception {
       
       RTopic
       
       <
       
       MUser
       
       > 
       
       topic 
       
       = 
       
       redisson.
       
       getTopic(
       
       Constant.
       
       REDISSON_EMAIL);
       
       topic.
       
       addListener(
       
       new 
       
       MessageListener
       
       <
       
       MUser
       
       >() {
       
       @Override
       
       public 
       
       void 
       
       onMessage(
       
       CharSequence 
       
       charSequence, 
       
       MUser 
       
       user) {
       
       LOGGER.
       
       info(
       
       "Redisson Listener receives message :{}", 
       
       user);
       
            }
       
        });
       
    }
       
       @Override
       
       public 
       
       int 
       
       getOrder() {
       
       return 
       
       1;
       
    }
       
}
      
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