SpringBoot使用@Cacheable出现预览工具乱码问题解决

直接使用注解进行缓存数据，我们再使用工具去预览存储的数据时发现是乱码，这是由于默认序列化的问题，默认是使用JdkSerializationRedisSerializer，我们将其更改即可

解决办法

我们重新定义一个org.springframework.data.redis.cache.RedisCacheConfiguration的Bean，并修改序列化器即可

/**
 * 此类解决 @Cacheable 存入的缓存使用预览工具时乱码问题
 *
 * @author YinShangwen
 * @since 2023/10/5 14:02
 */
@Configuration
public class RedisCacheConfig {
    @Bean
    public RedisCacheConfiguration redisCacheConfiguration(CacheProperties cacheProperties) {
        CacheProperties.Redis redisProperties = cacheProperties.getRedis();
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig();

        // 工具预览乱码问题
        config = config.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericFastJsonRedisSerializer()));

        if (redisProperties.getTimeToLive() != null) {
            config = config.entryTtl(redisProperties.getTimeToLive());
        }
        if (redisProperties.getKeyPrefix() != null) {
            config = config.prefixCacheNameWith(redisProperties.getKeyPrefix());
        }
        if (!redisProperties.isCacheNullValues()) {
            config = config.disableCachingNullValues();
        }
        if (!redisProperties.isUseKeyPrefix()) {
            config = config.disableKeyPrefix();
        }
        return config;
    }
}

⚠️
注意：如果之前有@Cacheable方式存储的缓存需要清理掉。否则会因为序列化/反序列化方式不一致而导致错误

源码导读

RedisCache#put

找到 org.springframework.data.redis.cache.RedisCache#put 方法。这个方法就是最终存入的方法

/*
 * (non-Javadoc)
 * @see org.springframework.cache.Cache#put(java.lang.Object, java.lang.Object)
 */
@Override
public void put(Object key, @Nullable Object value) {

    Object cacheValue = preProcessCacheValue(value);

    if (!isAllowNullValues() && cacheValue == null) {

        throw new IllegalArgumentException(String.format(
                "Cache '%s' does not allow 'null' values. Avoid storing null via '@Cacheable(unless=\"#result == null\")' or configure RedisCache to allow 'null' via RedisCacheConfiguration.",
                name));
    }

    cacheWriter.put(name, createAndConvertCacheKey(key), serializeCacheValue(cacheValue), cacheConfig.getTtl());
}

serializeCacheValue

我们注意到serializeCacheValue(cacheValue)

private final RedisCacheConfiguration cacheConfig;
/**
 * Serialize the value to cache.
 *
 * @param value must not be {@literal null}.
 * @return never {@literal null}.
 */
protected byte[] serializeCacheValue(Object value) {

    if (isAllowNullValues() && value instanceof NullValue) {
        return BINARY_NULL_VALUE;
    }

    return ByteUtils.getBytes(cacheConfig.getValueSerializationPair().write(value));
}

getValueSerializationPair

再看 cacheConfig.getValueSerializationPair() 是什么

private final SerializationPair<Object> valueSerializationPair;
/**
 * @return never {@literal null}.
 */
public SerializationPair<Object> getValueSerializationPair() {
    return valueSerializationPair;
}

这个变量就是最终决定序列化的类了，如何设置呢？在RedisCacheConfiguration中有如下方法

/**
 * Define the {@link SerializationPair} used for de-/serializing cache values.
 *
 * @param valueSerializationPair must not be {@literal null}.
 * @return new {@link RedisCacheConfiguration}.
 */
public RedisCacheConfiguration serializeValuesWith(SerializationPair<?> valueSerializationPair) {

    Assert.notNull(valueSerializationPair, "ValueSerializationPair must not be null!");

    return new RedisCacheConfiguration(ttl, cacheNullValues, usePrefix, keyPrefix, keySerializationPair,
            valueSerializationPair, conversionService);
}

默认的RedisCacheConfiguration如何被装载

找到类org.springframework.boot.autoconfigure.cache.RedisCacheConfiguration

注意：类名相同但包路径不相同
org.springframework.boot.autoconfigure.cache.RedisCacheConfiguration
org.springframework.data.redis.cache.RedisCacheConfiguration

class RedisCacheConfiguration {
    
    ...
    
	private org.springframework.data.redis.cache.RedisCacheConfiguration createConfiguration(
			CacheProperties cacheProperties, ClassLoader classLoader) {
		Redis redisProperties = cacheProperties.getRedis();
		org.springframework.data.redis.cache.RedisCacheConfiguration config = org.springframework.data.redis.cache.RedisCacheConfiguration
				.defaultCacheConfig();
        // 重点
		config = config.serializeValuesWith(
				SerializationPair.fromSerializer(new JdkSerializationRedisSerializer(classLoader)));
        
		if (redisProperties.getTimeToLive() != null) {
			config = config.entryTtl(redisProperties.getTimeToLive());
		}
		if (redisProperties.getKeyPrefix() != null) {
			config = config.prefixCacheNameWith(redisProperties.getKeyPrefix());
		}
		if (!redisProperties.isCacheNullValues()) {
			config = config.disableCachingNullValues();
		}
		if (!redisProperties.isUseKeyPrefix()) {
			config = config.disableKeyPrefix();
		}
		return config;
	}

}