基于 Spring Aop 环绕通知实现 Redis 缓存双删功能(示例代码)

基于 spring aop 常规应用场景多是用于日志记录以及实现 redis 分布式锁，在 github 中也有项目是把它拿来当作缓存的异常捕捉。从而避免影响实际业务的开发；在某天，笔者有个业务开发是给某个服务模块增加 redis 缓存。增加缓存就会涉及 redis 删除。所以笔者就在思考是不是可以用环绕通知的方式来进行实现

代码实现

结构示意图：

自定义注解 RedisDelByDbUpdate

@Repeatable 表示允许在同一个地方上使用相同的注解，没有该注解时贴相同注解会报错

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Repeatable(RedisDelByDbUpdateList.class)
public @interface RedisDelByDbUpdate {
    /**
     * 具体操作得缓存前缀
     */
    String redisPrefix() default "";

    /**
     * 具体的缓存名称，为空则删除 redisPrefix 下的所有缓存
     */
    String fieldName() default "";
}

自定义注解 RedisDelByUpdateList

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RedisDelByDbUpdateList {

    RedisDelByDbUpdate[] value();
}

具体实现 redis 双删逻辑

@Aspect
@Component
@Slf4j
public class RedisDelAspect_bak {
    //环绕增强
    @Autowired
    private RedisUtil redis;

    @Pointcut("@annotation(com.cili.baseserver.aop.annotation.RedisDelByDbUpdate) " +
            "|| @annotation(com.cili.baseserver.aop.annotation.RedisDelByDbUpdateList)")
    public void pointCut() {

    }

    // 线程池定长设置：最佳线程数目 = ((线程等待时间+线程CPU时间)/线程CPU时间 )* CPU数目
    ScheduledExecutorService threadPool = Executors.newScheduledThreadPool(26);

    /**
     * 环绕增强
     *
     * @param point
     * @return
     * @throws Throwable
     */
    @Around("pointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        MethodSignature signature = (MethodSignature) point.getSignature();
        Method method = signature.getMethod();

        RedisDelByDbUpdate redisDelByDbUpdate = method.getAnnotation(RedisDelByDbUpdate.class);
        if (redisDelByDbUpdate != null) {
            return singleRedisDel(redisDelByDbUpdate, point);
        }

        RedisDelByDbUpdateList updateList = method.getAnnotation(RedisDelByDbUpdateList.class);
        return arraysRedisDel(updateList, point);
    }

    private Object singleRedisDel(RedisDelByDbUpdate redisDelByDbUpdate, ProceedingJoinPoint point) throws Throwable {
        return handle(redisDelByDbUpdate, point, new IObjectCallback<Object>() {
            public <T> T callback() throws Throwable {
                return (T) point.proceed();
            }
        });
    }

    private Object arraysRedisDel(RedisDelByDbUpdateList updateList, ProceedingJoinPoint point) throws Throwable {
        RedisDelByDbUpdate[] redisDelByDbUpdates = updateList.value();
        for (int i = 0; i < redisDelByDbUpdates.length; i++) {
            boolean flag = i == redisDelByDbUpdates.length - 1 ? true : false;

            Object obj = handle(redisDelByDbUpdates[i], point, new IObjectCallback<Object>() {
                public <T> T callback() throws Throwable {
                    return flag ? (T) point.proceed() : null;
                }
            });
            if (flag) return obj;
        }
        return null;
    }

    private Object handle(RedisDelByDbUpdate redisDelByDbUpdate, ProceedingJoinPoint point,
                          IObjectCallback<Object> object) throws Throwable {

        String prefix = redisDelByDbUpdate.redisPrefix();
        String fieldName = redisDelByDbUpdate.fieldName();

        if (ValueUtil.isEmpty(prefix)) {
            log.info("redis缓存前缀不能为空");
            throw new BizException(BaseResponseCode.SYSTEM_BUSY);
        }

        Object arg = point.getArgs()[0];
        String key = "";
        String[] redisKeys = null;

        if (ValueUtil.isNotEmpty(fieldName)) {
            if (arg instanceof ArrayList) {
                redisKeys = ((ArrayList<?>) arg).stream().map(item -> prefix + item).toArray(String[]::new);
            } else {
                Map<String, Object> map = (Map<String, Object>) JsonUtil.toMap(JsonUtil.toJSON(point.getArgs()[0]));
                key = map.get(fieldName).toString();
            }
        } else {
            // 获取所有该前缀下缓存
            Set<String> keys = redis.keys(prefix + "*");
            redisKeys = keys.stream().toArray(String[]::new);
        }

        // 删除缓存
        String redisKey = prefix + key;
        delete(redisKey, redisKeys);
        Object result = object.callback();

        // 延时删除
        try {
            String[] finalRedisKeys = redisKeys;
            threadPool.schedule(new Runnable() {
                @Override
                public void run() {
                    delete(redisKey, finalRedisKeys);
                }
            }, 500, TimeUnit.MILLISECONDS);
        } catch (Exception e) {
            log.error("线程池延时删除缓存失败:{}", redisKey);
        }
        return result;
    }

    private void delete(String redisKey, String[] redisKeys) {
        if (ValueUtil.isEmpty(redisKeys)) {
            redis.delete(redisKey);
            return;
        }
        redis.del(redisKeys);
    }
}

注解使用示例

public class Test {
    @Override
    @RedisDelByDbUpdate(redisPrefix = RedisConstant.BANNER, fieldName = "ids")
    @RedisDelByDbUpdate(redisPrefix = RedisConstant.BANNER_LIST)
    public void batchDeleted(List<String> ids) throws BizException {
        if (CollectionUtils.isEmpty(ids)) {
            log.info("banner ID 不能为空");
            throw new BizException(BaseResponseCode.PARAM_IS_NOT_NULL);
        }
        try {
            bannerMapper.batchDeleted(ids);
        } catch (Exception e) {
            log.error("==>批量删除Banner错误:{}<==", e);
            throw new BizException(BaseResponseCode.SYSTEM_BUSY);
        }
    }
}

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