redis实现消息队列，点对点及发布订阅

解决redis序列化乱码问题

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.StringRedisSerializer;

@Configuration
public class RedisConfig {

    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(redisConnectionFactory);
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(new StringRedisSerializer());
        return template;
    }
}

1.点对点方式
 

    /**
     * 测试redis队列
     */
    @GetMapping("/senRedisMsgTest")
    public void senRedisMsgTest() {
        redisTemplate.opsForList().leftPush("username", "abcd");
        redisTemplate.opsForList().leftPush("username", "efgh");
        redisTemplate.opsForList().leftPush("username", "qwer");
        String username = String.valueOf(redisTemplate.opsForList().rightPop("username"));
        System.err.println(username);
    }

缺点是用rightPop()从redis队列中获取放入的元素时，只会按顺序拿出一条，如果是频繁写入，会存在无法全量拉取的问题

2.发布订阅模式

1.定义发布者

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;

@Service
public class RedisPublisher {

    @Autowired
    private RedisTemplate<String, Object>  redisTemplate;

    public void publish(String channel, String message) {
        redisTemplate.convertAndSend(channel, message);
    }
}

2.发布者测试代码

@Autowired
private RedisPublisher redisPublisher;


@GetMapping("/publish")
public String publish() {
    redisPublisher.publish("user_channel", "testMsg");
    return "Message published!";
}

3.配置订阅者配置类

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.listener.ChannelTopic;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.data.redis.listener.adapter.MessageListenerAdapter;

@Configuration
public class RedisSubscriberConfig {
    
    @Bean
    RedisMessageListenerContainer container(RedisConnectionFactory connectionFactory,
                                            MessageListenerAdapter listenerAdapter) {

        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(connectionFactory);
        container.addMessageListener(listenerAdapter, new ChannelTopic("user_channel"));
        return container;
    }

    @Bean
    MessageListenerAdapter listenerAdapter(RedisSubscriber receiver) {
        return new MessageListenerAdapter(receiver, "onMessage");
    }
}

4.订阅者接受处理消息

import org.springframework.stereotype.Component;

@Component
public class RedisSubscriber {

    public void onMessage(String message, String pattern) {
        System.err.println(message);
        System.err.println("Received <" + pattern + "> message: " + message);
    }
}

结果图：

发布订阅模式，在a服务写入时，b服务实时监听，进行处理，完美解决，需保证ab服务是同一个redis服务，且订阅者配置类中的channel和监听的方法名与发布者一致