/**
 * SpringBoot緩存示例項目啟動類
 */
@SpringBootApplication
@EnableCaching  // 啟用SpringBoot的緩存支持
public class CacheDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(CacheDemoApplication.class, args);
    }
    /**
     * 配置日志以顯示緩存操作
     */
    @Bean
    public LoggingCacheErrorHandler cacheErrorHandler() {
        return new LoggingCacheErrorHandler();
    }
}

/**
 * 用戶服務(wù)實現(xiàn)類，演示@Cacheable注解的基本用法
 */
@Service
public class UserServiceImpl implements UserService {
    private final UserRepository userRepository;
    public UserServiceImpl(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
    @Override
    @Cacheable(value = "users", key = "#id")
    public User getUserById(Long id) {
        // 模擬數(shù)據(jù)庫查詢的耗時操作
        try {
            Thread.sleep(2000);  // 模擬2秒的查詢延遲
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
        return userRepository.findById(id)
                .orElseThrow(() -> new RuntimeException("User not found"));
    }
}

/**
 * 產(chǎn)品服務(wù)，展示@Cacheable的高級屬性用法
 */
@Service
public class ProductService {
    private final ProductRepository productRepository;
    public ProductService(ProductRepository productRepository) {
        this.productRepository = productRepository;
    }
    @Cacheable(
        cacheNames = "products",  // 緩存名稱
        key = "#category.concat('-').concat(#price)",  // 組合鍵
        condition = "#price > 100",  // 僅緩存價格大于100的產(chǎn)品
        unless = "#result == null",  // 不緩存null結(jié)果
        cacheManager = "productCacheManager"  // 指定緩存管理器
    )
    public List<Product> findProductsByCategoryAndPrice(String category, double price) {
        // 模擬復(fù)雜查詢
        return productRepository.findByCategoryAndPriceGreaterThan(category, price);
    }
}

/**
 * 緩存配置類，演示多種緩存管理器的配置
 */
@Configuration
public class CacheConfig {
    /**
     * 配置基于Caffeine的本地緩存管理器
     */
    @Bean
    @Primary
    public CacheManager caffeineCacheManager() {
        CaffeineCacheManager cacheManager = new CaffeineCacheManager();
        // 全局緩存配置
        cacheManager.setCaffeine(Caffeine.newBuilder()
                .expireAfterWrite(30, TimeUnit.MINUTES)  // 寫入后30分鐘過期
                .maximumSize(1000)  // 最大緩存條目數(shù)
                .recordStats());  // 記錄緩存統(tǒng)計信息
        // 預(yù)設(shè)緩存名稱
        cacheManager.setCacheNames(Arrays.asList("users", "products", "orders"));
        return cacheManager;
    }
    /**
     * 配置Redis緩存管理器，用于分布式緩存
     */
    @Bean
    public CacheManager redisCacheManager(RedisConnectionFactory connectionFactory) {
        // Redis緩存配置
        RedisCacheConfiguration cacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
                .entryTtl(Duration.ofMinutes(60))  // 設(shè)置TTL為60分鐘
                .disableCachingNullValues()  // 禁止緩存null值
                .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer()))
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));
        // 為不同的緩存設(shè)置不同的配置
        Map<String, RedisCacheConfiguration> cacheConfigurations = new HashMap<>();
        cacheConfigurations.put("users", cacheConfiguration.entryTtl(Duration.ofMinutes(10)));
        cacheConfigurations.put("products", cacheConfiguration.entryTtl(Duration.ofHours(1)));
        return RedisCacheManager.builder(connectionFactory)
                .cacheDefaults(cacheConfiguration)
                .withInitialCacheConfigurations(cacheConfigurations)
                .build();
    }
}

/**
 * 自定義緩存鍵生成器
 */
@Component("customKeyGenerator")
public class CustomKeyGenerator implements KeyGenerator {
    @Override
    public Object generate(Object target, Method method, Object... params) {
        StringBuilder key = new StringBuilder();
        // 添加類名
        key.append(target.getClass().getSimpleName()).append(":");
        // 添加方法名
        key.append(method.getName()).append(":");
        // 處理參數(shù)
        for (Object param : params) {
            if (param instanceof User) {
                // 對于User類型參數(shù)，使用其id作為鍵的一部分
                key.append(((User) param).getId());
            } else if (param != null) {
                // 對于其他參數(shù)，使用其toString()方法
                key.append(param.toString());
            } else {
                key.append("null");
            }
            key.append(":");
        }
        // 移除末尾的冒號
        if (key.charAt(key.length() - 1) == ':') {
            key.deleteCharAt(key.length() - 1);
        }
        return key.toString();
    }
}
/**
 * 使用自定義鍵生成器的服務(wù)方法
 */
@Service
public class OrderService {
    @Cacheable(cacheNames = "orders", keyGenerator = "customKeyGenerator")
    public Order getOrderDetails(Long orderId, String customerCode) {
        // 業(yè)務(wù)邏輯...
        return new Order(orderId, customerCode, /* 其他訂單信息 */);
    }
}

/**
 * 演示緩存同步與失效的服務(wù)類
 */
@Service
public class ProductInventoryService {
    private final ProductRepository productRepository;
    public ProductInventoryService(ProductRepository productRepository) {
        this.productRepository = productRepository;
    }
    @Cacheable(cacheNames = "inventory", key = "#productId")
    public int getProductInventory(Long productId) {
        // 從數(shù)據(jù)庫查詢庫存
        return productRepository.findInventoryByProductId(productId);
    }
    @CachePut(cacheNames = "inventory", key = "#productId")
    public int updateProductInventory(Long productId, int newInventory) {
        // 更新數(shù)據(jù)庫庫存
        productRepository.updateInventory(productId, newInventory);
        return newInventory;  // 返回值將被緩存
    }
    @CacheEvict(cacheNames = "inventory", key = "#productId")
    public void invalidateInventoryCache(Long productId) {
        // 僅清除緩存，不執(zhí)行實際業(yè)務(wù)邏輯
        // 方法體可以為空，注解會處理緩存清除
    }
    // 批量清除緩存
    @CacheEvict(cacheNames = "inventory", allEntries = true)
    public void clearAllInventoryCache() {
        // 清除inventory緩存中的所有條目
        // 例如在庫存批量更新后調(diào)用
    }
}

/**
 * 緩存監(jiān)控配置
 */
@Configuration
@EnableCaching
public class CacheMonitoringConfig extends CachingConfigurerSupport {
    private static final Logger logger = LoggerFactory.getLogger(CacheMonitoringConfig.class);
    /**
     * 自定義緩存解析器，添加日志記錄
     */
    @Override
    public CacheResolver cacheResolver() {
        return new LoggingCacheResolver(caffeineCacheManager());
    }
    /**
     * 自定義緩存錯誤處理器
     */
    @Override
    public CacheErrorHandler errorHandler() {
        return new CacheErrorHandler() {
            @Override
            public void handleCacheGetError(RuntimeException exception, Cache cache, Object key) {
                logger.error("Cache get error for cache: {} and key: {}", cache.getName(), key, exception);
            }
            @Override
            public void handleCachePutError(RuntimeException exception, Cache cache, Object key, Object value) {
                logger.error("Cache put error for cache: {} and key: {}", cache.getName(), key, exception);
            }
            @Override
            public void handleCacheEvictError(RuntimeException exception, Cache cache, Object key) {
                logger.error("Cache evict error for cache: {} and key: {}", cache.getName(), key, exception);
            }
            @Override
            public void handleCacheClearError(RuntimeException exception, Cache cache) {
                logger.error("Cache clear error for cache: {}", cache.getName(), exception);
            }
        };
    }
    /**
     * 緩存統(tǒng)計信息收集任務(wù)
     */
    @Scheduled(fixedRate = 60000)  // 每分鐘執(zhí)行一次
    public void reportCacheStatistics() {
        CaffeineCacheManager cacheManager = (CaffeineCacheManager) caffeineCacheManager();
        cacheManager.getCacheNames().forEach(cacheName -> {
            com.github.benmanes.caffeine.cache.Cache<Object, Object> nativeCache = 
                    (com.github.benmanes.caffeine.cache.Cache<Object, Object>) 
                    ((CaffeineCache) cacheManager.getCache(cacheName)).getNativeCache();
            CacheStats stats = nativeCache.stats();
            logger.info("Cache: {} stats - Hit rate: {}, Eviction count: {}, Load time: {}ms",
                    cacheName,
                    String.format("%.2f", stats.hitRate() * 100) + "%",
                    stats.evictionCount(),
                    stats.totalLoadTime() / 1_000_000);
        });
    }
}