feat(cache): 模板读写基础(set/get/delete/exists/expire + TTL 抖动 + 滑动续期)

src/main/java/com/njcn/middle/cache/template/RedisCacheEnhanceTemplate.java

@@ -0,0 +1,116 @@
+package com.njcn.middle.cache.template;
+
+import com.alibaba.fastjson.TypeReference;
+import com.njcn.middle.cache.autoconfig.RedisCacheProperties;
+import com.njcn.middle.cache.support.CacheKeyBuilder;
+import com.njcn.middle.cache.support.CacheValueCodec;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.redis.core.StringRedisTemplate;
+
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+
+/**
+ * Redis 缓存增强模板。
+ *
+ * <p>底层 {@link StringRedisTemplate} 存字符串,fastjson 序列化。本类(Task 4)实现读写基础;
+ * {@code getOrLoad} 三防(穿透/雪崩/击穿)由 Task 5 追加。
+ */
+@Slf4j
+public class RedisCacheEnhanceTemplate {
+
+    private final StringRedisTemplate redis;
+    private final CacheKeyBuilder keyBuilder;
+    private final CacheValueCodec codec;
+    private final RedisCacheProperties props;
+
+    public RedisCacheEnhanceTemplate(StringRedisTemplate redis, CacheKeyBuilder keyBuilder,
+                                     CacheValueCodec codec, RedisCacheProperties props) {
+        this.redis = redis;
+        this.keyBuilder = keyBuilder;
+        this.codec = codec;
+        this.props = props;
+    }
+
+    // ---- 写 ----
+
+    public void set(String key, Object value) {
+        set(key, value, props.getDefaultTtlSeconds());
+    }
+
+    public void set(String key, Object value, long ttlSeconds) {
+        redis.opsForValue().set(keyBuilder.build(key), codec.encode(value),
+                applyJitter(ttlSeconds), TimeUnit.SECONDS);
+    }
+
+    // ---- 读 ----
+
+    public <T> T get(String key, Class<T> type) {
+        return doGet(key, raw -> codec.decode(raw, type));
+    }
+
+    public <T> T get(String key, TypeReference<T> type) {
+        return doGet(key, raw -> codec.decode(raw, type));
+    }
+
+    private <T> T doGet(String key, Function<String, T> decoder) {
+        String dataKey = keyBuilder.build(key);
+        String raw = redis.opsForValue().get(dataKey);
+        if (raw == null || codec.isNullSentinel(raw)) {
+            return null;
+        }
+        T value;
+        try {
+            value = decoder.apply(raw);
+        } catch (RuntimeException e) {
+            throw new IllegalStateException("cache decode failed, key=" + dataKey, e);
+        }
+        slidingTouch(dataKey);
+        return value;
+    }
+
+    // ---- 删 / 判存 ----
+
+    public boolean delete(String key) {
+        return Boolean.TRUE.equals(redis.delete(keyBuilder.build(key)));
+    }
+
+    public boolean exists(String key) {
+        return Boolean.TRUE.equals(redis.hasKey(keyBuilder.build(key)));
+    }
+
+    // ---- 续期 ----
+
+    public boolean expire(String key, long ttlSeconds) {
+        return Boolean.TRUE.equals(
+                redis.expire(keyBuilder.build(key), applyJitter(ttlSeconds), TimeUnit.SECONDS));
+    }
+
+    // ---- 内部 ----
+
+    /** 滑动过期:开启时对已存在的真实值 key 续期(直接对 dataKey 操作,失败忽略)。 */
+    private void slidingTouch(String dataKey) {
+        if (!props.isSlidingExpireEnabled()) {
+            return;
+        }
+        try {
+            redis.expire(dataKey, applyJitter(props.getDefaultTtlSeconds()), TimeUnit.SECONDS);
+        } catch (RuntimeException e) {
+            log.warn("[redis-cache] sliding expire failed key={}", dataKey, e);
+        }
+    }
+
+    /** 在原 TTL 上叠加 [0, ttl*ratio] 的随机抖动(只增不减);ratio<=0 或 ttl<=0 时原样返回。 */
+    long applyJitter(long ttlSeconds) {
+        double ratio = props.getJitterRatio();
+        if (ratio <= 0 || ttlSeconds <= 0) {
+            return ttlSeconds;
+        }
+        long bound = (long) (ttlSeconds * ratio);
+        if (bound <= 0) {
+            return ttlSeconds;
+        }
+        return ttlSeconds + ThreadLocalRandom.current().nextLong(bound + 1);
+    }
+}