Redis缓存穿透，缓存击穿，缓存雪崩实战代码总结

package com.macro.mall.portal.service.impl;

import com.macro.mall.common.utils.JsonUtils;
import com.macro.mall.common.utils.RedisUtil;
import com.macro.mall.model.PmsProduct;
import com.macro.mall.portal.dao.PmsProductDao;
import com.macro.mall.portal.service.PmsProductService;
import com.mysql.cj.util.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.BoundHashOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;
import redis.clients.jedis.Jedis;

import javax.annotation.Resource;
import java.util.List;
import java.util.Random;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

/**
 * 商品管理Service实现类
 * Created by macro on 2018/4/26.
 */
@Service
public class PmsProductServiceImpl implements PmsProductService {
    
    
    private static final Logger LOGGER = LoggerFactory.getLogger(PmsProductServiceImpl.class);
    @Autowired
    private PmsProductDao pmsProductDao;
    @Autowired
    private RedisUtil redisUtil;
    @Resource
    private RedisTemplate<String, Object> redisTemplate;
    private static final String KEY_PREFIX = "sku:info:id:";
    private static final String KEY = "sku:id:";
    //锁名称前缀
    public static final String LOCK_PREFIX = "redis:lock:id:";

  /**
     * 查询商品详情
     *
     * @param id
     * @return
     */
    @Override
    public PmsProduct list(Long id,String ip) {
    
    
        System.out.println("当前" + ip + "正在访问");
        //商品详情的key
        String key = KEY_PREFIX;
        String lockKey = LOCK_PREFIX + id;
        String infoKey = KEY + id;
        // 创建布隆过滤器对象，防止缓存击穿
       /* BloomFilter<Integer> filter = BloomFilter.create(
                Funnels.integerFunnel(),
                15000,
                0.01);
        //添加数据到布隆过滤器
        String ids = id.toString();
        filter.putAll(Integer.valueOf(ids));*/
        //查询缓存中是否存在
        if (redisUtil.hasKey(key)) {
    
    
            //查询缓存
            return (PmsProduct) redisUtil.get(key);
        } else {
    
    
                System.out.println("ip为" + ip + "在缓存中没有查到，申请分布式锁" + lockKey);
                //设置分布式锁，防止缓存击穿
                String token = UUID.randomUUID().toString();
                //redisTemplate设置分布式锁
                //boolean lock = redisUtil.lock(lockKey);
                Jedis jedis = new Jedis("localhost", 6379);
                //防止删除别人的锁
                String lock = jedis.set(lockKey, token, "nx", "px", 10 * 1000);
                if (null != lock && "OK".equals(lock)) {
    
    
                    //设置成功，有权在锁有效时间内查询数据库
                    PmsProduct list = pmsProductDao.list(id);
                    //防止某用户抢不到锁
                    try {
    
    
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
    
    
                        e.printStackTrace();
                    }
                    if (list != null) {
    
    
                        BoundHashOperations<String, Object, Object> stringObjectObjectBoundHashOperations = redisTemplate.boundHashOps(key);
                        //放入redis
                        stringObjectObjectBoundHashOperations.put(infoKey, JsonUtils.serialize(list));
                        Random r = new Random();
                        //设置key的随机过期时间，防止缓存雪崩
                        stringObjectObjectBoundHashOperations.expire(r.nextInt(123), TimeUnit.SECONDS);
                        return list;
                    } else {
    
    
                        //防止缓存穿透，设置为null的key以及过期时间
                        BoundHashOperations<String, Object, Object> hashOperations = redisTemplate.boundHashOps(key);
                        hashOperations.put(key, "");
                        hashOperations.expire(60 * 3, TimeUnit.SECONDS);
                    }
                    //判断是否是删除自己的锁
                    String localToken = jedis.get(lockKey);
                    if (null != localToken && token.equals(localToken)) {
    
    
                        String script = "if redis.call('get',KEYS[1] == ARGV[1] then return redis.call('del',KEYS[1]) else return 0 end";
                        Long eval = (Long) jedis.eval(script, Integer.parseInt(lockKey),localToken);
                        if (eval != null && eval != 0) {
    
    
                            //使用lua脚本在高并发情况下，获取key的同时删除key
                            jedis.del(lockKey);
                        }
                        System.out.println("ip" + ip + "申请分布式锁成功，并已删除");
                    }
                    //redisTemplate释放分布式锁
                    //redisUtil.deleteLock(key);
                } else {
    
    
                    System.out.println("ip为" + ip + "申请分布式锁失败" + lockKey);
                    //设置自旋,重新访问
                    try {
    
    
                        Thread.sleep(3000);
                    } catch (InterruptedException e) {
    
    
                        e.printStackTrace();
                    }
                    //直接return,防止产生未执行线程
                    return list(id, ip);
                }
            }
            return null;
        }
}

/**
	 * 获得锁
	 *
	 * @param lock
	 * @return
	 */
	public boolean lock(String lock) {
    
    
		return (boolean) redisTemplate.execute((RedisCallback) connection -> {
    
    
			//获取时间毫秒值
			long expireAt = System.currentTimeMillis() + LOCK_EXPIRE + 1;
			//获取锁
			Boolean acquire = connection.setNX(lock.getBytes(), String.valueOf(expireAt).getBytes());
			if (acquire) {
    
    
				return true;
			} else {
    
    
				byte[] bytes = connection.get(lock.getBytes());
				//非空判断
				if (Objects.nonNull(bytes) && bytes.length > 0) {
    
    
					long expireTime = Long.parseLong(new String(bytes));
					// 如果锁已经过期
					if (expireTime < System.currentTimeMillis()) {
    
    
						// 重新加锁，防止死锁
						byte[] set = connection.getSet(lock.getBytes(), String.valueOf(System.currentTimeMillis() + LOCK_EXPIRE + 1).getBytes());
						return Long.parseLong(new String(set)) < System.currentTimeMillis();
					}
				}
			}
			return false;
		});
	}

	/**
	 * 删除锁
	 *
	 * @param key
	 */
	public void deleteLock(String key) {
    
    
		redisTemplate.delete(key);
	}

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