Question

我在spring boot应用程序中使用spring-data-redis来缓存数据。我使用Mongo作为我的主要数据源，Redis作为缓存。当我第一次点击API时，它从Mongo获取记录并将其保存在Cache中，并将MyObject正确返回给客户端。但是当我第二次点击API时，它会在Cache中找到记录，并且在尝试将其反序列化为MyObject时，它就会出现。总是遇到强制转换异常：

java.lang.ClassCastException：无法强制转换java.util.LinkedHashMap 到MyObject

这是我的Redis配置：

public class MyConfiguration {
    @Bean
    public CacheManager cacheManager(RedisTemplate<String, MyObject> redisTemplate) {
        return new RedisCacheManager(redisTemplate);
    }

    @Bean
    public RedisTemplate<String, MyObject> redisTemplate(RedisConnectionFactory connectionFactory, ObjectMapper objectMapper) {
        StringRedisSerializer serializer = new StringRedisSerializer();
        GenericJackson2JsonRedisSerializer hashValueSerializer = new GenericJackson2JsonRedisSerializer(objectMapper);
        RedisTemplate<String, MyObject> redisTemplate = new RedisTemplate<>();
        redisTemplate.setKeySerializer(serializer);
        redisTemplate.setValueSerializer(hashValueSerializer);
        redisTemplate.setConnectionFactory(connectionFactory);
        return redisTemplate;
    }
}

发现此处报告的问题相同：Spring-data-redis @Cacheable java.lang.ClassCastException: java.util.HashMap cannot be cast to java.lang.String

我研究了很长时间但没有想法。请建议。非常感谢。

Answer 1

对我来说序列化和反序列化任何对象都可以。在此示例中，缓存管理器设置为TTL，您可以根据需要将其删除。

@Configuration
@EnableCaching
public class RedisCacheConfig {

  @Value("${spring.redis.host}")
  private String redisHostName;

  @Value("${spring.redis.port}")
  private int redisPort;

  @Bean
  public LettuceConnectionFactory redisConnectionFactory() {
    return new LettuceConnectionFactory(new RedisStandaloneConfiguration(redisHostName, redisPort));
  }

  @Bean
  public RedisTemplate<Object, Object> redisTemplate() {
    RedisTemplate<Object, Object> redisTemplate = new RedisTemplate<Object, Object>();
    redisTemplate.setConnectionFactory(redisConnectionFactory());
    return redisTemplate;
  }

  @Bean
  @Primary
  public RedisCacheManager redisCacheManager(LettuceConnectionFactory lettuceConnectionFactory) {
    RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig().disableCachingNullValues()
      .entryTtl(Duration.ofMinutes(1))
      .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(RedisSerializer.json()));

    redisCacheConfiguration.usePrefix();

    return RedisCacheManager.RedisCacheManagerBuilder.fromConnectionFactory(lettuceConnectionFactory)
      .cacheDefaults(redisCacheConfiguration).build();

  }
}

Answer 2

对我来说，只需在键值GenericJackson2JsonRedisSerializer()和no，serializer hash key参数的新value serializer即可>

@Bean
    public RedisTemplate<String, Object> redisTemplate(LettuceConnectionFactory lettuceConnectionFactory, ObjectMapper objectMapper) {
        final RedisTemplate<String, Object> redisTemplate = new RedisTemplate<String, Object>();
        redisTemplate.setConnectionFactory(lettuceConnectionFactory);
        // value serializer
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        // hash value serializer
        redisTemplate.setHashKeySerializer(new StringRedisSerializer());
        redisTemplate.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());

        logger.info("wiring up Redistemplate...");
        return redisTemplate;
    }

Spring-data-redis @Cacheable java.lang.ClassCastException：java.util.LinkedHashMap无法强制转换为MyObject

2 个答案: