<!-- SpringBoot緩存核心依賴(lài) -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-cache</artifactId>
</dependency>
<!-- Caffeine本地緩存 -->
<dependency>
    <groupId>com.github.ben-manes.caffeine</groupId>
    <artifactId>caffeine</artifactId>
    <version>3.1.8</version>
</dependency>
<!-- Redis依賴(lài) -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!-- Redisson分布式鎖 -->
<dependency>
    <groupId>org.redisson</groupId>
    <artifactId>redisson-spring-boot-starter</artifactId>
    <version>3.23.3</version>
</dependency>

spring:
  # Redis配置
  redis:
    host: 127.0.0.1
    port: 6379
    password: 123456
    lettuce:
      pool:
        max-active: 8
        max-idle: 8
        min-idle: 2
        max-wait: 1000ms
    timeout: 3000ms
  # 緩存配置
  cache:
    type: caffeine
    caffeine:
      # 初始容量、最大容量、過(guò)期時(shí)間（寫(xiě)入后30分鐘過(guò)期）
      initial-capacity: 100
      maximum-size: 1000
      expire-after-write: 30m

# 自定義緩存配置
cache:
  # 空值緩存過(guò)期時(shí)間（5分鐘）
  null-value-expire: 5m
  # 熱點(diǎn)數(shù)據(jù)預(yù)熱key前綴
  hot-data-prefix: "hot:"
  # 分布式鎖前綴
  lock-prefix: "cache:lock:"

import com.github.benmanes.caffeine.cache.Caffeine;
import org.springframework.cache.CacheManager;
import org.springframework.cache.caffeine.CaffeineCacheManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import java.time.Duration;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class CacheConfig {

    // Caffeine緩存管理器（本地緩存）
    @Bean
    public CacheManager caffeineCacheManager() {
        CaffeineCacheManager cacheManager = new CaffeineCacheManager();
        // 配置Caffeine緩存參數(shù)：初始容量100，最大容量1000，寫(xiě)入后30分鐘過(guò)期
        cacheManager.setCaffeine(Caffeine.newBuilder()
                .initialCapacity(100)
                .maximumSize(1000)
                .expireAfterWrite(Duration.ofMinutes(30)));
        return cacheManager;
    }

    // Redis緩存管理器（分布式緩存）
    @Bean
    public RedisCacheManager redisCacheManager(RedisConnectionFactory connectionFactory) {
        // 序列化配置（避免Redis存儲(chǔ)亂碼）
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofMinutes(30)) // 默認(rèn)過(guò)期時(shí)間30分鐘
                .serializeKeysWith(RedisSerializationContext.SerializationPair
                        .fromSerializer(new StringRedisSerializer()))
                .serializeValuesWith(RedisSerializationContext.SerializationPair
                        .fromSerializer(new GenericJackson2JsonRedisSerializer()));

        // 自定義不同緩存的過(guò)期時(shí)間（如空值緩存5分鐘）
        Map<String, RedisCacheConfiguration> cacheConfigs = new HashMap<>();
        cacheConfigs.put("nullValueCache", config.entryTtl(Duration.ofMinutes(5)));

        return RedisCacheManager.builder(connectionFactory)
                .cacheDefaults(config)
                .withInitialCacheConfigurations(cacheConfigs)
                .build();
    }
}

import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
import java.util.concurrent.TimeUnit;

@Component
public class CacheUtil {

    @Resource
    private CacheManager caffeineCacheManager;
    @Resource
    private RedisCacheManager redisCacheManager;
    @Resource
    private RedisTemplate<String, Object> redisTemplate;
    @Resource
    private RedissonClient redissonClient;
    @Resource
    private BloomFilterUtil bloomFilterUtil; // 布隆過(guò)濾器工具類(lèi)

    // 緩存查詢(xún)核心方法：key-緩存鍵，clazz-返回類(lèi)型，dbLoader-數(shù)據(jù)庫(kù)查詢(xún)邏輯
    public <T> T getCache(String key, Class<T> clazz, DataLoader<T> dbLoader) {
        // 1. 布隆過(guò)濾器校驗(yàn)：無(wú)效key直接返回null
        if (!bloomFilterUtil.contains(key)) {
            return null;
        }

        // 2. 查詢(xún)Caffeine本地緩存
        Cache caffeineCache = caffeineCacheManager.getCache("localCache");
        T localValue = caffeineCache.get(key, clazz);
        if (localValue != null) {
            return localValue;
        }

        // 3. 查詢(xún)Redis分布式緩存
        Cache redisCache = redisCacheManager.getCache("redisCache");
        T redisValue = redisCache.get(key, clazz);
        if (redisValue != null) {
            // Redis命中，同步到本地緩存
            caffeineCache.put(key, redisValue);
            return redisValue;
        }

        // 4. 緩存未命中，分布式鎖控制數(shù)據(jù)庫(kù)查詢(xún)
        RLock lock = redissonClient.getLock("cache:lock:" + key);
        try {
            // 嘗試獲取鎖，最多等待3秒，持有鎖10秒
            if (lock.tryLock(3, 10, TimeUnit.SECONDS)) {
                // 再次查詢(xún)Redis（防止其他線(xiàn)程已更新緩存）
                redisValue = redisCache.get(key, clazz);
                if (redisValue != null) {
                    caffeineCache.put(key, redisValue);
                    return redisValue;
                }

                // 5. 查詢(xún)數(shù)據(jù)庫(kù)
                T dbValue = dbLoader.load();
                if (dbValue != null) {
                    // 數(shù)據(jù)庫(kù)有結(jié)果，更新各級(jí)緩存
                    redisCache.put(key, dbValue);
                    caffeineCache.put(key, dbValue);
                } else {
                    // 數(shù)據(jù)庫(kù)無(wú)結(jié)果，緩存空值（5分鐘過(guò)期）
                    Cache nullValueCache = redisCacheManager.getCache("nullValueCache");
                    nullValueCache.put(key, null);
                    caffeineCache.put(key, null);
                }
                return dbValue;
            } else {
                // 獲取鎖失敗，返回默認(rèn)值或拋出異常
                throw new RuntimeException("緩存更新繁忙，請(qǐng)稍后重試");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            return null;
        } finally {
            // 釋放鎖
            if (lock.isHeldByCurrentThread()) {
                lock.unlock();
            }
        }
    }

    // 數(shù)據(jù)加載函數(shù)式接口（封裝數(shù)據(jù)庫(kù)查詢(xún)邏輯）
    @FunctionalInterface
    public interface DataLoader<T> {
        T load();
    }
}

// 緩存清除方法（用于數(shù)據(jù)庫(kù)更新后）
public void clearCache(String key) {
    // 1. 清除本地緩存
    Cache caffeineCache = caffeineCacheManager.getCache("localCache");
    caffeineCache.evict(key);
    // 2. 清除Redis緩存
    Cache redisCache = redisCacheManager.getCache("redisCache");
    redisCache.evict(key);
    // 3. 清除空值緩存
    Cache nullValueCache = redisCacheManager.getCache("nullValueCache");
    nullValueCache.evict(key);
}

import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
import javax.annotation.Resource;
import java.util.List;

@Component
public class HotDataPreloader implements CommandLineRunner {

    @Resource
    private CacheUtil cacheUtil;
    @Resource
    private ProductMapper productMapper; // 數(shù)據(jù)庫(kù)DAO層

    @Override
    public void run(String... args) throws Exception {
        // 加載熱點(diǎn)商品數(shù)據(jù)（如銷(xiāo)量前100的商品）
        List<Product> hotProducts = productMapper.selectHotProducts(100);
        for (Product product : hotProducts) {
            String key = "product:" + product.getId();
            // 存入本地緩存和Redis
            cacheUtil.caffeineCacheManager.getCache("localCache").put(key, product);
            cacheUtil.redisCacheManager.getCache("redisCache").put(key, product);
        }
        System.out.println("熱點(diǎn)數(shù)據(jù)預(yù)熱完成，共加載" + hotProducts.size() + "條數(shù)據(jù)");
    }
}