redis實現發佈訂閱功能

Redis 發佈訂閱(pub/sub)是一種消息通信模式：發送者(pub)發送消息，訂閱者(sub)接收消息。

是一個簡單的消息隊列

以下結合SpringBoot實際使用

1、創建消息監聽程序

/**
 * Redis消息監聽程序
 *
 */
public class RedisMessageListener implements MessageListener {
	private final Logger logger = LoggerFactory.getLogger(RedisMessageListener.class);
	@Resource
	private RedisTemplate<Serializable, Serializable> redisTemplate;

	@Override
	public void onMessage(Message message, byte[] pattern) {
		String msgPattern = new String(pattern);
		logger.info(msgPattern);
		byte[] channel = message.getChannel();
		String msgChannel = (String) redisTemplate.getKeySerializer().deserialize(channel);
		logger.info(msgChannel);
		byte[] body = message.getBody();
		String msgBody = (String) redisTemplate.getValueSerializer().deserialize(body);
		logger.info(msgBody);
	}

}

2、redis消息容器配置

/**
 * RedisTemplate 配置
 */
@Bean("redisTemplate")
public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
	RedisTemplate<Object, Object> template = new RedisTemplate<Object, Object>();
	template.setConnectionFactory(connectionFactory);
	// 使用Jackson2JsonRedisSerializer來序列化和反序列化redis的value值（默認使用JDK的序列化方式）
	Jackson2JsonRedisSerializer<Serializable> serializer = new Jackson2JsonRedisSerializer<Serializable>(
			Serializable.class);
	ObjectMapper mapper = new ObjectMapper();
	mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
	mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
	serializer.setObjectMapper(mapper);
	StringRedisSerializer keySerializer = new StringRedisSerializer();
	template.setKeySerializer(keySerializer);
	template.setValueSerializer(serializer);
	template.setHashKeySerializer(keySerializer);
	template.setHashValueSerializer(serializer);
	template.afterPropertiesSet();
	return template;
}

/** 消息監聽器配置 */
@Bean
public RedisMessageListener redisMessageListener() {
	return new RedisMessageListener();
}

/** 消息監聽器列表配置 */
@Bean
public Map<MessageListener, Collection<? extends Topic>> redisListeners(RedisMessageListener messageListener) {
	Map<MessageListener, Collection<? extends Topic>> listeners = new HashMap<>();
	Collection<Topic> lstTopic = new ArrayList<>();
	// 可以配置多個監聽
	lstTopic.add(new PatternTopic("chat*"));
	listeners.put(messageListener, lstTopic);
	return listeners;
}
/** 執行隊列 */
@Bean
public ThreadPoolTaskScheduler threadPoolTaskScheduler() {
	ThreadPoolTaskScheduler executor = new ThreadPoolTaskScheduler();
	executor.setPoolSize(10);
	return executor;
}

/** 消息監聽容器 */
@Bean
public RedisMessageListenerContainer redisMessageListenerContainer(RedisConnectionFactory connectionFactory,
		Map<MessageListener, Collection<? extends Topic>> redisListeners) {
	RedisMessageListenerContainer container = new RedisMessageListenerContainer();
	container.setConnectionFactory(connectionFactory);
	container.setTaskExecutor(threadPoolTaskScheduler());
	container.setMessageListeners(redisListeners);
	return container;
}

3、發送消息

使用 convertAndSend() 方法發送消息

String channel = "chatTest";
String msg = "你好";
redisTemplate.convertAndSend(channel, msg);

因爲消息監聽器中配置了通配符（chat*），所以發送到頻道（chatTest）一樣會被監聽到

redis的發佈訂閱功能，實現了簡單的mq功能，併發能力沒有kafka等專業的mq中間件高

參考

https://blog.csdn.net/qq_34561892/article/details/81515850