Redis Key 过期事件监听

Posted 2022-03-25 程序员超时空

目的是为了实现定时推送，又不想写定时任务扫

1、redis 开启key过期通知

修改redis server 配置文件，开启keyt过期听通知配置

notify-keyspace-events Ex

2、 key过期Listener

@Component
public class RedisKeyExpiredListener extends JedisPubSub 

    private final static Logger logger = LoggerFactory.getLogger(RedisKeyExpiredListener.class);

    @Autowired
    private PushMsgService pushMsgService;

    private static final String PREFIX_EVENT_KEY = "xxx:event:sms:";

    @Override
    public void onMessage(String channel, String message) 
        logger.debug("redis event key :", message);
        if (message.startsWith(PREFIX_EVENT_KEY)) 
            pushMsgService.pushSmsForSms(Long.parseLong(message.substring(message.lastIndexOf(":") + 1)));
        
    

3、注册redis key过期Listener

@PostConstruct
private void init() 
	// 因为此方法阻塞线程
	new Thread(new Runnable() 
	    @Override
	    public void run() 
		// 订阅redis key过期时间，需要reids 服务器配置notify-keyspace-events Ex
		jedisPool.getResource().subscribe(redisKeyExpiredListener, "__keyevent@2__:expired");
	    
	).start();

keyevent@2:expired
__keyevent必须以此开头；
@2 表示监听第二个数据库；
:expired 表示过期事件

4、设置过期时间

Jedis jedis = jedisPool.getResource();
jedis.select(2);
jedis.set(PREFIX_EVENT_KEY + teaching.getId(), String.valueOf(teaching.getId()));
jedis.expire(PREFIX_EVENT_KEY + teaching.getId(), expireTime.intValue());