package com.hmdp.service.impl;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_TTL;
/**
 * <p>
 *  服務(wù)實(shí)現(xiàn)類
 * </p>
 *
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryShopById(Long id) {
        //1.去redis中查詢商品是否存在
        String key = CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopJson)){
            //2.存在，直接返回給用戶
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return Result.ok(shop);
        }
        //3.不存在，帶著id去數(shù)據(jù)庫查詢是否存在商品
        Shop shop = getById(id);
        if (shop == null){
            //4.不存在，返回錯(cuò)誤信息
            Result.fail("商品信息不存在！");
        }
        //5.存在，存入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop));
        //6.返回商品信息
        return Result.ok(shop);
    }
}

package com.hmdp.service.impl;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_KEY;
import static com.hmdp.utils.RedisConstants.CACHE_SHOP_TTL;
/**
 * <p>
 *  服務(wù)實(shí)現(xiàn)類
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryShopById(Long id) {
        //1.去redis中查詢商品是否存在
        String key = CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopJson)){
            //2.存在，直接返回給用戶
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return Result.ok(shop);
        }
        //3.不存在，帶著id去數(shù)據(jù)庫查詢是否存在商品
        Shop shop = getById(id);
        if (shop == null){
            //4.不存在，返回錯(cuò)誤信息
            Result.fail("商品信息不存在！");
        }
        //5.存在，存入redis(并設(shè)置超時(shí)時(shí)間)
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //6.返回商品信息
        return Result.ok(shop);
    }
    @Override
    @Transactional
    public Result updateShop(Shop shop) {
        //1.先更新數(shù)據(jù)庫
        updateById(shop);
        //2.刪除redis緩存
        String key = CACHE_SHOP_KEY+shop.getId();
        stringRedisTemplate.delete(key);
        return null;
    }
}

package com.hmdp.service.impl;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;
import static com.hmdp.utils.RedisConstants.*;
/**
 * <p>
 *  服務(wù)實(shí)現(xiàn)類
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryShopById(Long id) {
        //1.去redis中查詢商品是否存在
        String key = CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopJson)){
            //2.存在，直接返回給用戶
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return Result.ok(shop);
        }
        //判斷命中的是否為空字符串
        /**
         * (這里重點(diǎn)講一下為什么是不等于：因?yàn)槲覀儷@取到的shopJson為null是，上面的isNotBlank方法會(huì)返回false，導(dǎo)致成為了不命中的效果)
         */
        if (shopJson != null){
            return Result.fail("商品信息不存在！");
        }
        //3.不存在，帶著id去數(shù)據(jù)庫查詢是否存在商品
        Shop shop = getById(id);
        if (shop == null){
            // 4.將空值存入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            //5.不存在，返回錯(cuò)誤信息
            Result.fail("商品信息不存在！");
        }
        //6.存在，存入redis(并設(shè)置超時(shí)時(shí)間)
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回商品信息
        return Result.ok(shop);
    }
}

    //獲取鎖
    public Boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //釋放鎖方法
    public void unlock(String key){
        stringRedisTemplate.delete(key);
    }

package com.hmdp.service.impl;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import static com.hmdp.utils.RedisConstants.*;
/**
 * <p>
 *  服務(wù)實(shí)現(xiàn)類
 * </p>
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryShopById(Long id) {
        //互斥鎖緩存擊穿
        Shop shop = queryWithMutex(id);
        if (shop == null){
            Result.fail("商品信息不存在!");
        }
        //8.返回商品信息
        return Result.ok(shop);
    }
    // 緩存穿透解決——互斥鎖
    public Shop queryWithMutex(Long id){
        //1.去redis中查詢商品是否存在
        String key = CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        if (StrUtil.isNotBlank(shopJson)){
            //2.存在，直接返回給用戶
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判斷命中的是否為空字符串
        if (shopJson != null){
            return null;
        }
        Shop shop = null;
        String lockKey = LOCK_SHOP_KEY+id;
        try {
            //3.緩存重建
            //3.1嘗試獲取鎖
            Boolean isLock = tryLock(lockKey);
            //3.2判斷獲取鎖是否成功，如果休眠重試
            if (!isLock){
                //休眠
                Thread.sleep(50);
                //重試用遞歸
                queryWithMutex(id);
            }
            //3.3如果成功，去數(shù)據(jù)庫查找數(shù)據(jù)
            shop = getById(id);
            if (shop == null){
                // 4.將空值存入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                //5.不存在，返回錯(cuò)誤信息
                Result.fail("商品信息不存在！");
            }
            //6.存在，存入redis(并設(shè)置超時(shí)時(shí)間)
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7.釋放鎖
            unlock(lockKey);
        }
        //8.返回商品信息
        return shop;
    }
    //獲取鎖
    public Boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //釋放鎖方法
    public void unlock(String key){
        stringRedisTemplate.delete(key);
    }
}

package com.hmdp.utils;
import lombok.Data;
import java.time.LocalDateTime;
@Data
public class RedisData {
    private LocalDateTime expireTime;
    private Object data;
}

//給商品信息添加一個(gè)過期時(shí)間字段，并存入redis當(dāng)中
    public void saveShop2Redis(Long id,Long expireSeconds){
        Shop shop = getById(id);
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }

package com.hmdp.service.impl;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import static com.hmdp.utils.RedisConstants.*;
/**
 * <p>
 *  服務(wù)實(shí)現(xiàn)類
 * </p>
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryShopById(Long id) {
        //邏輯過期解決緩存擊穿問題
//        Shop shop = queryWithLogicalExpire(id);
        if (shop == null){
            Result.fail("商品信息不存在!");
        }
        //8.返回商品信息
        return Result.ok(shop);
    }
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryWithLogicalExpire(Long id){
        //1.去redis中查詢商品是否存在
        String key = CACHE_SHOP_KEY+id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判斷是否命中
        //3.未命中
        if (StrUtil.isBlank(shopJson)){
            return null;
        }
        //4.命中,先把redis中的數(shù)據(jù)反序列化成java對(duì)象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        //4.1獲取過期時(shí)間
        LocalDateTime expireTime = redisData.getExpireTime();
        //4.2獲取商品對(duì)象
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        //5.判斷是否過期
        if (expireTime.isAfter(LocalDateTime.now())){
            //未過期,直接返回shop
            return shop;
        }
        //6.過期，重建緩存
        //6.1嘗試獲取鎖，并判斷
        String lockKey = LOCK_SHOP_KEY + id;
        Boolean isLock = tryLock(lockKey);
        if (isLock){
            //5.2 如果成功，開啟一個(gè)獨(dú)立的線程,重建緩存
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //重建緩存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //釋放鎖
                    unlock(lockKey);
                }
            });
        }
        //6.2返回舊的商品信息
        return shop;
    }
    //獲取鎖
    public Boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //釋放鎖方法
    public void unlock(String key){
        stringRedisTemplate.delete(key);
    }
    //給商品信息添加一個(gè)過期時(shí)間字段，并存入redis當(dāng)中
    public void saveShop2Redis(Long id,Long expireSeconds){
        Shop shop = getById(id);
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
}