136 lines
4.9 KiB
Java
136 lines
4.9 KiB
Java
package edu.whut.smilepicturebackend.manager.cache;
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import com.fasterxml.jackson.databind.ObjectMapper;
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import com.github.benmanes.caffeine.cache.Cache;
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import com.github.benmanes.caffeine.cache.Caffeine;
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import lombok.RequiredArgsConstructor;
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import org.springframework.data.redis.core.Cursor;
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import org.springframework.data.redis.core.ScanOptions;
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import org.springframework.data.redis.core.StringRedisTemplate;
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import org.springframework.data.redis.core.ValueOperations;
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import org.springframework.stereotype.Service;
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import com.fasterxml.jackson.core.type.TypeReference;
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import java.nio.charset.StandardCharsets;
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import java.time.Duration;
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import java.util.Collection;
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import java.util.Map;
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import java.util.concurrent.TimeUnit;
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import java.util.function.Supplier;
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@Service
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@RequiredArgsConstructor
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public class MyCacheManager {
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private final ObjectMapper mapper;
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/**
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* 本地缓存
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*/
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private final Cache<String, String> localCache = Caffeine.newBuilder()
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.initialCapacity(1024)
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.maximumSize(10_000L) // 最大 10000 条
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.expireAfterWrite(Duration.ofMinutes(5)) // 缓存 5 分钟后移除
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.build();
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/**
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* 分布式缓存
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*/
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private final StringRedisTemplate stringRedisTemplate;
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public <T> T getFromCacheOrDatabase(
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String cacheKey,
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TypeReference<T> typeRef,
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Supplier<T> dbSupplier,
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int redisExpireSeconds) {
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// 1) 本地缓存
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String cachedValue = localCache.getIfPresent(cacheKey);
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if (cachedValue != null) {
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try {
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return mapper.readValue(cachedValue, typeRef);
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} catch (Exception ignore) {}
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}
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// 2) Redis
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ValueOperations<String, String> ops = stringRedisTemplate.opsForValue();
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cachedValue = ops.get(cacheKey);
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if (cachedValue != null) {
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localCache.put(cacheKey, cachedValue);
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try {
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return mapper.readValue(cachedValue, typeRef);
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} catch (Exception ignore) {}
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}
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// 3) DB 回源
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T dbValue = dbSupplier.get();
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// ===== 空值缓存防穿透 =====
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if (isEmptyValue(dbValue)) {
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String emptyJson = "{}";
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ops.set(cacheKey, emptyJson, 60, TimeUnit.SECONDS); // 缓存60秒
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localCache.put(cacheKey, emptyJson);
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return dbValue;
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}
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try {
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String json = mapper.writeValueAsString(dbValue);
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ops.set(cacheKey, json, redisExpireSeconds, TimeUnit.SECONDS);
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localCache.put(cacheKey, json);
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} catch (Exception ignore) {}
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return dbValue;
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}
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/**
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* 判断值是否为空，用于空值缓存
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*/
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private boolean isEmptyValue(Object value) {
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if (value == null) {
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return true;
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}
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if (value instanceof Collection) {
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return ((Collection<?>) value).isEmpty();
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}
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if (value instanceof Map) {
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return ((Map<?, ?>) value).isEmpty();
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}
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// 这里可以根据你的项目补充 Page 判空逻辑
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if (value instanceof com.baomidou.mybatisplus.extension.plugins.pagination.Page) {
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return ((com.baomidou.mybatisplus.extension.plugins.pagination.Page<?>) value).getRecords().isEmpty();
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}
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return false;
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}
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/**
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* 删除缓存
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* @param spaceId
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*/
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public void clearCacheBySpaceId(Long spaceId) {
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// 构造命名空间，公共图库使用 "public"，其他空间使用 spaceId
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String namespace = (spaceId == null) ? "public" : String.valueOf(spaceId);
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// Redis SCAN 模式匹配的前缀
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String pattern = "smilepicture:listPictureVOByPage:spaceId:" + namespace + ":*";
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// 使用 SCAN 命令进行遍历，查找所有相关的缓存 key
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ScanOptions options = ScanOptions.scanOptions().match(pattern).count(100).build();
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Cursor<byte[]> cursor = stringRedisTemplate.execute(
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(redisConnection) -> redisConnection.scan(options),
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true
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);
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// 删除匹配的缓存
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while (cursor.hasNext()) {
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byte[] rawKey = cursor.next();
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String cacheKey = new String(rawKey, StandardCharsets.UTF_8); // 转换 byte[] 为 String
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stringRedisTemplate.delete(cacheKey); // 删除 Redis 缓存
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}
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// 删除本地缓存 Caffeine
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// 由于 Caffeine 不支持像 Redis 那样通过模式匹配查询所有 key，我们依然按分页模式来清除
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for (int current = 1; current <= 100; current++) { // 假设最多查询100页
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for (int size = 10; size <= 100; size += 10) {
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String cacheKey = "smilepicture:listPictureVOByPage:spaceId:" + namespace + ":current:" + current + ":size:" + size;
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localCache.invalidate(cacheKey); // 清除本地缓存
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}
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}
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}
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}
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