在一个需求中，需要当redis的key删除或过期的时候往日志表中插入一条对应的记录。那么如何监听redis的过期key呢？
1.首先需要设置redis配置文件
notify-keyspace-events Ex，
或者使用命令 CONFIG set notify-keyspace-events Ex。
那么notify-keyspace-events 后面都有哪些参数呢

输入的参数中至少要有一个K或者E，否则其余参数不会有任何的通知生效。

2.springboot中配置redis

@Configuration
public class RedisConfig {

    @Bean
    @Primary
    public <T> RedisTemplate<String, T> getRedisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<String, T> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(redisConnectionFactory);
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new GenericFastJsonRedisSerializer());
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(new GenericFastJsonRedisSerializer());
        return redisTemplate;
    }

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

    @Bean
    public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory) {
        StringRedisTemplate stringRedisTemplate = new StringRedisTemplate();
        stringRedisTemplate.setConnectionFactory(redisConnectionFactory);
        return stringRedisTemplate;
    }

    @Bean
    public RedisScript<Boolean> hitMaxScript() {
        DefaultRedisScript<Boolean> redisScript = new DefaultRedisScript<>();
        redisScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("scripts/hitmax.lua")));
        redisScript.setResultType(Boolean.class);
        return redisScript;
    }

    @Bean
    RedisMessageListenerContainer container(RedisConnectionFactory redisConnectionFactory) {
        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(redisConnectionFactory);
        container.setTaskExecutor(executor());
        Topic topic = new PatternTopic(RedisKeyExpirationListener.LISTENER_PATTERN);
        container.addMessageListener(new RedisKeyExpirationListener(), topic);
        return container;
    }

    @Bean
    public Executor executor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(10);
        executor.setMaxPoolSize(20);
        executor.setQueueCapacity(100);
        executor.setKeepAliveSeconds(60);
        executor.setThreadNamePrefix("V-Thread");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.initialize();
        return executor;
    }
}

3.自定义一个监听器重写对应的onMessage方法

@Component
public class RedisKeyExpirationListener implements MessageListener {
    public static final String LISTENER_PATTERN = "__key*@*__:*";
	@Resource
    private OperationLimitService operationLimitService;
    
    @Override
    public void onMessage(Message message, byte[] pattern) {
        System.err.println("触发监听器。。。。。。");
        String body = new String(message.getBody());
        String channel = new String(message.getChannel());
        System.out.println("onMessage >> "+String.format("channel: %s, body: %s, bytes: %s",channel,body,new String(pattern)));
    }
}

但上面的service注入的是一个null，猜测原因是监听器的执行早于spring的注入。所以又增加了获取bean的代码

@Slf4j
@Configuration
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

    private static ApplicationContext applicationContext = null;

    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
        assertContextInjected();
        return applicationContext;
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        log.debug("从SpringContextHolder中取出Bean:" + name);
        assertContextInjected();
        return (T) applicationContext.getBean(name);
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    public static <T> T getBean(Class<T> requiredType) {
        assertContextInjected();
        return applicationContext.getBean(requiredType);
    }

    /**
     * 清除SpringContextHolder中的ApplicationContext为Null.
     */
    public static void clearHolder() {
        log.info("清除SpringContextHolder中的ApplicationContext:"
                + applicationContext);
        applicationContext = null;
    }

    /**
     * 实现ApplicationContextAware接口, 注入Context到静态变量中.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
//		logger.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);

        if (SpringContextHolder.applicationContext != null) {
            log.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);
        }

        SpringContextHolder.applicationContext = applicationContext; // NOSONAR
    }

    /**
     * 实现DisposableBean接口, 在Context关闭时清理静态变量.
     */
    @Override
    public void destroy() throws Exception {
        SpringContextHolder.clearHolder();
    }

    /**
     * 检查ApplicationContext不为空.
     */
    private static void assertContextInjected() {
        if(applicationContext == null) {
            throw new IllegalStateException("applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder或在SpringBoot启动类中注册SpringContextHolder.");
        }
    }
}

然后这个bean直接从applicationContext中获取就行了