Question

这是Kotlin的示例代码。

@Configuration

@Bean("cacheManager1hour")
fun cacheManager1hour(@Qualifier("cacheConfig") cacheConfiguration: RedisCacheConfiguration, redisConnectionFactory: RedisConnectionFactory): CacheManager {
    cacheConfiguration.entryTtl(Duration.ofSeconds(60 * 60))
    return RedisCacheManager.builder(redisConnectionFactory)
            .cacheDefaults(cacheConfiguration)
            .build()
}

@Bean("cacheConfig")
fun cacheConfig(objectMapper:ObjectMapper): RedisCacheConfiguration {
    return RedisCacheConfiguration.defaultCacheConfig()
            .computePrefixWith { cacheName -> "yaya:$cacheName:" }
            .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(StringRedisSerializer()))
            .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(GenericJackson2JsonRedisSerializer()))

}

@RestController

@Cacheable(value = "book", key = "#root.methodName", cacheManager = "cacheManager1hour")
fun getBook(): Book {
    return Book()
}

class Book  {
    var asdasd:String? = "TEST"
    var expires_in = 123
}

GenericJackson2JsonRedisSerializer无法处理＆＃34; kotlin类＆＃34;我们需要添加＆＃39; @class作为属性＆＃39;到Redis缓存条目。

无论如何，为什么我们需要@class？ Spring上下文知道结果的类型，为什么它没有通过？我们有两个好处：

少记忆
对于序列化程序很容易，即objectMapper.readValue(str, T)

带注释的Spring代码

// org.springframework.cache.interceptor.CacheAspectSupport
@Nullable
private Cache.ValueWrapper findInCaches(CacheOperationContext context, Object key) {
    for (Cache cache : context.getCaches()) {
        // --> maybe we can pass the context.method.returnType to doGet
        Cache.ValueWrapper wrapper = doGet(cache, key); 
        if (wrapper != null) {
            if (logger.isTraceEnabled()) {
                logger.trace("Cache entry for key '" + key + "' found in cache '" + 
        cache.getName() + "'");
            }
            return wrapper;
        }
    }
    return null;
}

// org.springframework.data.redis.cache.RedisCache
@Override
protected Object lookup(Object key) { 
    // -> there will get the deserialized type can pass to Jackson

    byte[] value = cacheWriter.get(name, createAndConvertCacheKey(key));

    if (value == null) {
        return null;
    }

    return deserializeCacheValue(value);
}

Answer 1

您的退货类型可能是：

一些抽象类
某些界面

在这种情况下，您的返回类型对反序列化对象几乎没有用。编码实际的类始终有效。

为什么Spring @Cacheable没有将带注释的方法的结果类型传递给它的解串器？

1 个答案: