public <R, ID> R queryShopWithPassthrough(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallBack
            , Long expireTime, TimeUnit timeUnit) {
        String key = keyPrefix + id;
        //获取Redis中数据
        String json = stringRedisTemplate.opsForValue().get(key);
        //是否有值
        if (StrUtil.isNotBlank(json)) {
            //有值则直接返回
            R bean = JSONUtil.toBean(json, type);
            return bean;
        }
        //是否为空字符串
        if (json != null) {
            return null;
        }
        //获取数据库中数据并转化为R类型
        R r = dbFallBack.apply(id);
        String rStr = JSONUtil.toJsonStr(r);
        //数据库和缓存中都不存在，在Redis中存放空字符串
        if (r == null) {
            //存入空字符串,防止缓存穿透
            this.set(key, "", expireTime, timeUnit);
            return null;
        }
        //数据库中存在，缓存不存在，则存入Redis
        this.set(key, rStr, expireTime, timeUnit);
        return r;
    }

//使用互斥锁解决缓存击穿
private Result queryShopWithMutex(Long id) {
    String shopEntries = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY + id);
    Shop shop;
    //是否有值
    if (StrUtil.isNotBlank(shopEntries)) {
        shop = JSONUtil.toBean(shopEntries, Shop.class);
        return Result.ok(shop);
    }
    //添加互斥锁
    //1.获取锁
    String lockKey = RedisConstants.LOCK_SHOP_KEY + "" + id;
    try {
        boolean tryLock = tryLock(lockKey);
        //2.判断是否获取成功
        //2.1.失败则休眠或重试
        if (!tryLock){
            Thread.sleep(50);
            queryShopWithMutex(id);
        }
        //2.2.成功则获取数据库数据
        //数据库中存在，缓存不存在
        shop = getById(id);
        String shopStr = JSONUtil.toJsonStr(shop);
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY + id, shopStr, RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
    } catch (InterruptedException e) {
        throw new RuntimeException(e);
    }
    finally {
        unLock(lockKey);
    }
    return Result.ok(shop);
}
private boolean tryLock(String key){
    Boolean lock = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", RedisConstants.LOCK_SHOP_TTL, TimeUnit.SECONDS);
    return BooleanUtil.isTrue(lock);
}

private void unLock(String key){
    stringRedisTemplate.delete(key);
}

//缓存查询(使用逻辑过期解决缓存击穿)
public <R, ID> R queryShopWithLogicTime(String Cachekey, String lockkey, ID id, Class<R> type, Function<ID, R> dbToRedis
        , Long logicExpireTime, TimeUnit timeUnit) {
    //Redis的Key
    String key = Cachekey + id;
    //从Redis中获取JSON格式数据
    String redisDataEntries = stringRedisTemplate.opsForValue().get(key);
    //是否有值
    if (StrUtil.isBlank(redisDataEntries)) {
        //为空则直接返回
        return null;
    }
    //将RedisData的JSON转化成bean对象
    RedisData redisData = JSONUtil.toBean(redisDataEntries, RedisData.class);
    //获取redisData中的Data(JSON格式，需要转化成bean)
    R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
    //获取redisData的逻辑过期时间
    LocalDateTime expireTime = redisData.getExpireTime();
    //有值则判断是否过期
    if (expireTime.isAfter(LocalDateTime.now())) {
        //1.未过期则直接返回
        return r;
    }
    //2.已过期
    //2.1.尝试获取锁
    String lockKey = lockkey + id;
    boolean isLock = tryLock(lockKey);
    //2.1.1. 获取锁成功
    if (isLock) {
        CACHE_REBUILD_EXECUTOR.submit(() -> {
            try {
                //获取数据库并转换成R类型对象
                R r1 = dbToRedis.apply(id);
                //存入Redis
                this.setWithLogicTime(key, r1, logicExpireTime, timeUnit);
            } catch (Exception e) {
                throw new RuntimeException(e);
            } finally {
                unLock(lockKey);
            }
        });
    }
    //2.1.2. 获取锁失败
    return r;
}
//尝试获取锁
private boolean tryLock(String key) {
    Boolean lock = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", RedisConstants.LOCK_SHOP_TTL, TimeUnit.SECONDS);
    return BooleanUtil.isTrue(lock);
}
//删除锁
private void unLock(String key) {
    stringRedisTemplate.delete(key);
}

RedisData类：


package com.hmdp.utils;

import lombok.Data;

import java.time.LocalDateTime;

@Data
public class RedisData {
    private LocalDateTime expireTime;
    private Object data;
}